





Network Working Group                                         R. Housley
Request for Comments: 2459                                        SPYRUS
Category: Standards Track                                        W. Ford
                                                                VeriSign
                                                                 W. Polk
                                                                    NIST
                                                                 D. Solo
                                                                Citicorp
                                                            January 1999


                Internet X.509 Public Key Infrastructure
                      Certificate and CRL Profile

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (1999).  All Rights Reserved.

Abstract

   This memo profiles the X.509 v3 certificate and X.509 v2 CRL for use
   in the Internet.  An overview of the approach and model are provided
   as an introduction.  The X.509 v3 certificate format is described in
   detail, with additional information regarding the format and
   semantics of Internet name forms (e.g., IP addresses).  Standard
   certificate extensions are described and one new Internet-specific
   extension is defined.  A required set of certificate extensions is
   specified.  The X.509 v2 CRL format is described and a required
   extension set is defined as well.  An algorithm for X.509 certificate
   path validation is described. Supplemental information is provided
   describing the format of public keys and digital signatures in X.509
   certificates for common Internet public key encryption algorithms
   (i.e., RSA, DSA, and Diffie-Hellman).  ASN.1 modules and examples are
   provided in the appendices.

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119.





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   Please send comments on this document to the ietf-pkix@imc.org mail
   list.



                           TTTTaaaabbbblllleeee ooooffff CCCCoooonnnntttteeeennnnttttssss



   1  Introduction ................................................    5
   2  Requirements and Assumptions ................................    6
   2.1  Communication and Topology ................................    6
   2.2  Acceptability Criteria ....................................    7
   2.3  User Expectations .........................................    7
   2.4  Administrator Expectations ................................    7
   3  Overview of Approach ........................................    7
   3.1  X.509 Version 3 Certificate ...............................    9
   3.2  Certification Paths and Trust .............................   10
   3.3  Revocation ................................................   12
   3.4  Operational Protocols .....................................   13
   3.5  Management Protocols ......................................   13
   4  Certificate and Certificate Extensions Profile ..............   15
   4.1  Basic Certificate Fields ..................................   15
   4.1.1  Certificate Fields ......................................   16
   4.1.1.1  tbsCertificate ........................................   16
   4.1.1.2  signatureAlgorithm ....................................   16
   4.1.1.3  signatureValue ........................................   17
   4.1.2  TBSCertificate ..........................................   17
   4.1.2.1  Version ...............................................   17
   4.1.2.2  Serial number .........................................   18
   4.1.2.3  Signature .............................................   18
   4.1.2.4  Issuer ................................................   18
   4.1.2.5  Validity ..............................................   21
   4.1.2.5.1  UTCTime .............................................   22
   4.1.2.5.2  GeneralizedTime .....................................   22
   4.1.2.6  Subject ...............................................   22
   4.1.2.7  Subject Public Key Info ...............................   23
   4.1.2.8  Unique Identifiers ....................................   24
   4.1.2.9 Extensions .............................................   24
   4.2  Certificate Extensions ....................................   24
   4.2.1  Standard Extensions .....................................   25
   4.2.1.1  Authority Key Identifier ..............................   25
   4.2.1.2  Subject Key Identifier ................................   26
   4.2.1.3  Key Usage .............................................   27
   4.2.1.4  Private Key Usage Period ..............................   29
   4.2.1.5  Certificate Policies ..................................   29
   4.2.1.6  Policy Mappings .......................................   31
   4.2.1.7  Subject Alternative Name ..............................   32



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   4.2.1.8  Issuer Alternative Name ...............................   34
   4.2.1.9  Subject Directory Attributes ..........................   34
   4.2.1.10  Basic Constraints ....................................   35
   4.2.1.11  Name Constraints .....................................   35
   4.2.1.12  Policy Constraints ...................................   37
   4.2.1.13  Extended key usage field .............................   38
   4.2.1.14  CRL Distribution Points ..............................   39
   4.2.2  Private Internet Extensions .............................   40
   4.2.2.1  Authority Information Access ..........................   41
   5  CRL and CRL Extensions Profile ..............................   42
   5.1  CRL Fields ................................................   43
   5.1.1  CertificateList Fields ..................................   43
   5.1.1.1  tbsCertList ...........................................   44
   5.1.1.2  signatureAlgorithm ....................................   44
   5.1.1.3  signatureValue ........................................   44
   5.1.2  Certificate List "To Be Signed" .........................   44
   5.1.2.1  Version ...............................................   45
   5.1.2.2  Signature .............................................   45
   5.1.2.3  Issuer Name ...........................................   45
   5.1.2.4  This Update ...........................................   45
   5.1.2.5  Next Update ...........................................   45
   5.1.2.6  Revoked Certificates ..................................   46
   5.1.2.7  Extensions ............................................   46
   5.2  CRL Extensions ............................................   46
   5.2.1  Authority Key Identifier ................................   47
   5.2.2  Issuer Alternative Name .................................   47
   5.2.3  CRL Number ..............................................   47
   5.2.4  Delta CRL Indicator .....................................   48
   5.2.5  Issuing Distribution Point ..............................   48
   5.3  CRL Entry Extensions ......................................   49
   5.3.1  Reason Code .............................................   50
   5.3.2  Hold Instruction Code ...................................   50
   5.3.3  Invalidity Date .........................................   51
   5.3.4  Certificate Issuer ......................................   51
   6  Certificate Path Validation .................................   52
   6.1  Basic Path Validation .....................................   52
   6.2  Extending Path Validation .................................   56
   7  Algorithm Support ...........................................   57
   7.1  One-way Hash Functions ....................................   57
   7.1.1  MD2 One-way Hash Function ...............................   57
   7.1.2  MD5 One-way Hash Function ...............................   58
   7.1.3  SHA-1 One-way Hash Function .............................   58
   7.2  Signature Algorithms ......................................   58
   7.2.1  RSA Signature Algorithm .................................   59
   7.2.2  DSA Signature Algorithm .................................   60
   7.3  Subject Public Key Algorithms .............................   60
   7.3.1  RSA Keys ................................................   61
   7.3.2  Diffie-Hellman Key Exchange Key .........................   61



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   7.3.3  DSA Signature Keys ......................................   63
   8  References ..................................................   64
   9  Intellectual Property Rights ................................   66
   10  Security Considerations ....................................   67
   Appendix A.  ASN.1 Structures and OIDs .........................   70
   A.1 Explicitly Tagged Module, 1988 Syntax ......................   70
   A.2 Implicitly Tagged Module, 1988 Syntax ......................   84
   Appendix B.  1993 ASN.1 Structures and OIDs ....................   91
   B.1 Explicitly Tagged Module, 1993 Syntax ......................   91
   B.2 Implicitly Tagged Module, 1993 Syntax ......................  108
   Appendix C.  ASN.1 Notes .......................................  116
   Appendix D.  Examples ..........................................  117
   D.1  Certificate ...............................................  117
   D.2  Certificate ...............................................  120
   D.3  End-Entity Certificate Using RSA ..........................  123
   D.4  Certificate Revocation List ...............................  126
   Appendix E.  Authors' Addresses ................................  128
   Appendix F.  Full Copyright Statement ..........................  129

































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1  Introduction

   This specification is one part of a family of standards for the X.509
   Public Key Infrastructure (PKI) for the Internet.  This specification
   is a standalone document; implementations of this standard may
   proceed independent from the other parts.

   This specification profiles the format and semantics of certificates
   and certificate revocation lists for the Internet PKI.  Procedures
   are described for processing of certification paths in the Internet
   environment.  Encoding rules are provided for popular cryptographic
   algorithms.  Finally, ASN.1 modules are provided in the appendices
   for all data structures defined or referenced.

   The specification describes the requirements which inspire the
   creation of this document and the assumptions which affect its scope
   in Section 2.  Section 3 presents an architectural model and
   describes its relationship to previous IETF and ISO/IEC/ITU
   standards.  In particular, this document's relationship with the IETF
   PEM specifications and the ISO/IEC/ITU X.509 documents are described.

   The specification profiles the X.509 version 3 certificate in Section
   4, and the X.509 version 2 certificate revocation list (CRL) in
   Section 5. The profiles include the identification of ISO/IEC/ITU and
   ANSI extensions which may be useful in the Internet PKI. The profiles
   are presented in the 1988 Abstract Syntax Notation One (ASN.1) rather
   than the 1994 syntax used in the ISO/IEC/ITU standards.

   This specification also includes path validation procedures in
   Section 6.  These procedures are based upon the ISO/IEC/ITU
   definition, but the presentation assumes one or more self-signed
   trusted CA certificates.  Implementations are required to derive the
   same results but are not required to use the specified procedures.

   Section 7 of the specification describes procedures for
   identification and encoding of public key materials and digital
   signatures.  Implementations are not required to use any particular
   cryptographic algorithms.  However, conforming implementations which
   use the identified algorithms are required to identify and encode the
   public key materials and digital signatures as described.

   Finally, four appendices are provided to aid implementers.  Appendix
   A contains all ASN.1 structures defined or referenced within this
   specification.  As above, the material is presented in the 1988
   Abstract Syntax Notation One (ASN.1) rather than the 1994 syntax.
   Appendix B contains the same information in the 1994 ASN.1 notation
   as a service to implementers using updated toolsets.  However,
   Appendix A takes precedence in case of conflict.  Appendix C contains



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   notes on less familiar features of the ASN.1 notation used within
   this specification.  Appendix D contains examples of a conforming
   certificate and a conforming CRL.

2  Requirements and Assumptions

   The goal of this specification is to develop a profile to facilitate
   the use of X.509 certificates within Internet applications for those
   communities wishing to make use of X.509 technology. Such
   applications may include WWW, electronic mail, user authentication,
   and IPsec.  In order to relieve some of the obstacles to using X.509
   certificates, this document defines a profile to promote the
   development of certificate management systems; development of
   application tools; and interoperability determined by policy.

   Some communities will need to supplement, or possibly replace, this
   profile in order to meet the requirements of specialized application
   domains or environments with additional authorization, assurance, or
   operational requirements.  However, for basic applications, common
   representations of frequently used attributes are defined so that
   application developers can obtain necessary information without
   regard to the issuer of a particular certificate or certificate
   revocation list (CRL).

   A certificate user should review the certificate policy generated by
   the certification authority (CA) before relying on the authentication
   or non-repudiation services associated with the public key in a
   particular certificate.  To this end, this standard does not
   prescribe legally binding rules or duties.

   As supplemental authorization and attribute management tools emerge,
   such as attribute certificates, it may be appropriate to limit the
   authenticated attributes that are included in a certificate.  These
   other management tools may provide more appropriate methods of
   conveying many authenticated attributes.

2.1  Communication and Topology

   The users of certificates will operate in a wide range of
   environments with respect to their communication topology, especially
   users of secure electronic mail.  This profile supports users without
   high bandwidth, real-time IP connectivity, or high connection
   availability.  In addition, the profile allows for the presence of
   firewall or other filtered communication.







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   This profile does not assume the deployment of an X.500 Directory
   system.  The profile does not prohibit the use of an X.500 Directory,
   but other means of distributing certificates and certificate
   revocation lists (CRLs) may be used.

2.2  Acceptability Criteria

   The goal of the Internet Public Key Infrastructure (PKI) is to meet
   the needs of deterministic, automated identification, authentication,
   access control, and authorization functions. Support for these
   services determines the attributes contained in the certificate as
   well as the ancillary control information in the certificate such as
   policy data and certification path constraints.

2.3  User Expectations

   Users of the Internet PKI are people and processes who use client
   software and are the subjects named in certificates.  These uses
   include readers and writers of electronic mail, the clients for WWW
   browsers, WWW servers, and the key manager for IPsec within a router.
   This profile recognizes the limitations of the platforms these users
   employ and the limitations in sophistication and attentiveness of the
   users themselves.  This manifests itself in minimal user
   configuration responsibility (e.g., trusted CA keys, rules), explicit
   platform usage constraints within the certificate, certification path
   constraints which shield the user from many malicious actions, and
   applications which sensibly automate validation functions.

2.4  Administrator Expectations

   As with user expectations, the Internet PKI profile is structured to
   support the individuals who generally operate CAs.  Providing
   administrators with unbounded choices increases the chances that a
   subtle CA administrator mistake will result in broad compromise.
   Also, unbounded choices greatly complicate the software that shall
   process and validate the certificates created by the CA.

3  Overview of Approach

   Following is a simplified view of the architectural model assumed by
   the PKIX specifications.










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       +---+
       | C |                       +------------+
       | e | <-------------------->| End entity |
       | r |       Operational     +------------+
       | t |       transactions          ^
       |   |      and management         |  Management
       | / |       transactions          |  transactions
       |   |                             |                PKI users
       | C |                             v
       | R |       -------------------+--+-----------+----------------
       | L |                          ^              ^
       |   |                          |              |  PKI management
       |   |                          v              |      entities
       | R |                       +------+          |
       | e | <---------------------| RA   | <---+    |
       | p |  Publish certificate  +------+     |    |
       | o |                                    |    |
       | s |                                    |    |
       | I |                                    v    v
       | t |                                +------------+
       | o | <------------------------------|     CA     |
       | r |   Publish certificate          +------------+
       | y |   Publish CRL                         ^
       |   |                                       |
       +---+                        Management     |
                                    transactions   |
                                                   v
                                               +------+
                                               |  CA  |
                                               +------+

                          Figure 1 - PKI Entities

   The components in this model are:

   end entity:  user of PKI certificates and/or end user system that
                is the subject of a certificate;
   CA:          certification authority;
   RA:          registration authority, i.e., an optional system to
                which a CA delegates certain management functions;
   repository:  a system or collection of distributed systems that
                store certificates and CRLs and serves as a means of
                distributing these certificates and CRLs to end
                entities.







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3.1  X.509 Version 3 Certificate

   Users of a public key shall be confident that the associated private
   key is owned by the correct remote subject (person or system) with
   which an encryption or digital signature mechanism will be used.
   This confidence is obtained through the use of public key
   certificates, which are data structures that bind public key values
   to subjects.  The binding is asserted by having a trusted CA
   digitally sign each certificate. The CA may base this assertion upon
   technical means (a.k.a., proof of posession through a challenge-
   response protocol), presentation of the private key, or on an
   assertion by the subject.  A certificate has a limited valid lifetime
   which is indicated in its signed contents.  Because a certificate's
   signature and timeliness can be independently checked by a
   certificate-using client, certificates can be distributed via
   untrusted communications and server systems, and can be cached in
   unsecured storage in certificate-using systems.

   ITU-T X.509 (formerly CCITT X.509) or ISO/IEC/ITU 9594-8, which was
   first published in 1988 as part of the X.500 Directory
   recommendations, defines a standard certificate format [X.509]. The
   certificate format in the 1988 standard is called the version 1 (v1)
   format.  When X.500 was revised in 1993, two more fields were added,
   resulting in the version 2 (v2) format. These two fields may be used
   to support directory access control.

   The Internet Privacy Enhanced Mail (PEM) RFCs, published in 1993,
   include specifications for a public key infrastructure based on X.509
   v1 certificates [RFC 1422].  The experience gained in attempts to
   deploy RFC 1422 made it clear that the v1 and v2 certificate formats
   are deficient in several respects.  Most importantly, more fields
   were needed to carry information which PEM design and implementation
   experience has proven necessary.  In response to these new
   requirements, ISO/IEC/ITU and ANSI X9 developed the X.509 version 3
   (v3) certificate format.  The v3 format extends the v2 format by
   adding provision for additional extension fields.  Particular
   extension field types may be specified in standards or may be defined
   and registered by any organization or community. In June 1996,
   standardization of the basic v3 format was completed [X.509].

   ISO/IEC/ITU and ANSI X9 have also developed standard extensions for
   use in the v3 extensions field [X.509][X9.55].  These extensions can
   convey such data as additional subject identification information,
   key attribute information, policy information, and certification path
   constraints.






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   However, the ISO/IEC/ITU and ANSI X9 standard extensions are very
   broad in their applicability.  In order to develop interoperable
   implementations of X.509 v3 systems for Internet use, it is necessary
   to specify a profile for use of the X.509 v3 extensions tailored for
   the Internet.  It is one goal of this document to specify a profile
   for Internet WWW, electronic mail, and IPsec applications.
   Environments with additional requirements may build on this profile
   or may replace it.

3.2  Certification Paths and Trust

   A user of a security service requiring knowledge of a public key
   generally needs to obtain and validate a certificate containing the
   required public key. If the public-key user does not already hold an
   assured copy of the public key of the CA that signed the certificate,
   the CA's name, and related information (such as the validity period
   or name constraints), then it might need an additional certificate to
   obtain that public key.  In general, a chain of multiple certificates
   may be needed, comprising a certificate of the public key owner (the
   end entity) signed by one CA, and zero or more additional
   certificates of CAs signed by other CAs.  Such chains, called
   certification paths, are required because a public key user is only
   initialized with a limited number of assured CA public keys.

   There are different ways in which CAs might be configured in order
   for public key users to be able to find certification paths.  For
   PEM, RFC 1422 defined a rigid hierarchical structure of CAs.  There
   are three types of PEM certification authority:

      (a)  Internet Policy Registration Authority (IPRA):  This
      authority, operated under the auspices of the Internet Society,
      acts as the root of the PEM certification hierarchy at level 1.
      It issues certificates only for the next level of authorities,
      PCAs.  All certification paths start with the IPRA.

      (b)  Policy Certification Authorities (PCAs):  PCAs are at level 2
      of the hierarchy, each PCA being certified by the IPRA.  A PCA
      shall establish and publish a statement of its policy with respect
      to certifying users or subordinate certification authorities.
      Distinct PCAs aim to satisfy different user needs. For example,
      one PCA (an organizational PCA) might support the general
      electronic mail needs of commercial organizations, and another PCA
      (a high-assurance PCA) might have a more stringent policy designed
      for satisfying legally binding digital signature requirements.







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      (c)  Certification Authorities (CAs):  CAs are at level 3 of the
      hierarchy and can also be at lower levels. Those at level 3 are
      certified by PCAs.  CAs represent, for example, particular
      organizations, particular organizational units (e.g., departments,
      groups, sections), or particular geographical areas.

   RFC 1422 furthermore has a name subordination rule which requires
   that a CA can only issue certificates for entities whose names are
   subordinate (in the X.500 naming tree) to the name of the CA itself.
   The trust associated with a PEM certification path is implied by the
   PCA name. The name subordination rule ensures that CAs below the PCA
   are sensibly constrained as to the set of subordinate entities they
   can certify (e.g., a CA for an organization can only certify entities
   in that organization's name tree). Certificate user systems are able
   to mechanically check that the name subordination rule has been
   followed.

   The RFC 1422 uses the X.509 v1 certificate formats. The limitations
   of X.509 v1 required imposition of several structural restrictions to
   clearly associate policy information or restrict the utility of
   certificates.  These restrictions included:

      (a) a pure top-down hierarchy, with all certification paths
      starting from IPRA;

      (b) a naming subordination rule restricting the names of a CA's
      subjects; and

      (c) use of the PCA concept, which requires knowledge of individual
      PCAs to be built into certificate chain verification logic.
      Knowledge of individual PCAs was required to determine if a chain
      could be accepted.

   With X.509 v3, most of the requirements addressed by RFC 1422 can be
   addressed using certificate extensions, without a need to restrict
   the CA structures used.  In particular, the certificate extensions
   relating to certificate policies obviate the need for PCAs and the
   constraint extensions obviate the need for the name subordination
   rule.  As a result, this document supports a more flexible
   architecture, including:

      (a) Certification paths may start with a public key of a CA in a
      user's own domain, or with the public key of the top of a
      hierarchy.  Starting with the public key of a CA in a user's own
      domain has certain advantages.  In some environments, the local
      domain is the most trusted.





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      (b)  Name constraints may be imposed through explicit inclusion of
      a name constraints extension in a certificate, but are not
      required.

      (c)  Policy extensions and policy mappings replace the PCA
      concept, which permits a greater degree of automation.  The
      application can determine if the certification path is acceptable
      based on the contents of the certificates instead of a priori
      knowledge of PCAs. This permits automation of certificate chain
      processing.

3.3  Revocation

   When a certificate is issued, it is expected to be in use for its
   entire validity period.  However, various circumstances may cause a
   certificate to become invalid prior to the expiration of the validity
   period. Such circumstances include change of name, change of
   association between subject and CA (e.g., an employee terminates
   employment with an organization), and compromise or suspected
   compromise of the corresponding private key.  Under such
   circumstances, the CA needs to revoke the certificate.

   X.509 defines one method of certificate revocation.  This method
   involves each CA periodically issuing a signed data structure called
   a certificate revocation list (CRL).  A CRL is a time stamped list
   identifying revoked certificates which is signed by a CA and made
   freely available in a public repository.  Each revoked certificate is
   identified in a CRL by its certificate serial number. When a
   certificate-using system uses a certificate (e.g., for verifying a
   remote user's digital signature), that system not only checks the
   certificate signature and validity but also acquires a suitably-
   recent CRL and checks that the certificate serial number is not on
   that CRL.  The meaning of "suitably-recent" may vary with local
   policy, but it usually means the most recently-issued CRL.  A CA
   issues a new CRL on a regular periodic basis (e.g., hourly, daily, or
   weekly).  An entry is added to the CRL as part of the next update
   following notification of revocation. An entry may be removed from
   the CRL after appearing on one regularly scheduled CRL issued beyond
   the revoked certificate's validity period.

   An advantage of this revocation method is that CRLs may be
   distributed by exactly the same means as certificates themselves,
   namely, via untrusted communications and server systems.

   One limitation of the CRL revocation method, using untrusted
   communications and servers, is that the time granularity of
   revocation is limited to the CRL issue period.  For example, if a
   revocation is reported now, that revocation will not be reliably



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   notified to certificate-using systems until the next periodic CRL is
   issued -- this may be up to one hour, one day, or one week depending
   on the frequency that the CA issues CRLs.

   As with the X.509 v3 certificate format, in order to facilitate
   interoperable implementations from multiple vendors, the X.509 v2 CRL
   format needs to be profiled for Internet use.  It is one goal of this
   document to specify that profile.  However, this profile does not
   require CAs to issue CRLs. Message formats and protocols supporting
   on-line revocation notification may be defined in other PKIX
   specifications.  On-line methods of revocation notification may be
   applicable in some environments as an alternative to the X.509 CRL.
   On-line revocation checking may significantly reduce the latency
   between a revocation report and the distribution of the information
   to relying parties.  Once the CA accepts the report as authentic and
   valid, any query to the on-line service will correctly reflect the
   certificate validation impacts of the revocation.  However, these
   methods impose new security requirements; the certificate validator
   shall trust the on-line validation service while the repository does
   not need to be trusted.

3.4  Operational Protocols

   Operational protocols are required to deliver certificates and CRLs
   (or status information) to certificate using client systems.
   Provision is needed for a variety of different means of certificate
   and CRL delivery, including distribution procedures based on LDAP,
   HTTP, FTP, and X.500.  Operational protocols supporting these
   functions are defined in other PKIX specifications.  These
   specifications may include definitions of message formats and
   procedures for supporting all of the above operational environments,
   including definitions of or references to appropriate MIME content
   types.

3.5  Management Protocols

   Management protocols are required to support on-line interactions
   between PKI user and management entities.  For example, a management
   protocol might be used between a CA and a client system with which a
   key pair is associated, or between two CAs which cross-certify each
   other.  The set of functions which potentially need to be supported
   by management protocols include:

      (a)  registration:  This is the process whereby a user first makes
      itself known to a CA (directly, or through an RA), prior to that
      CA issuing  a certificate or certificates for that user.





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      (b)  initialization:  Before a client system can operate securely
      it is necessary to install key materials which have the
      appropriate relationship with keys stored elsewhere in the
      infrastructure.  For example, the client needs to be securely
      initialized with the public key and other assured information of
      the trusted CA(s), to be used in validating certificate paths.
      Furthermore, a client typically needs to be initialized with its
      own key pair(s).

      (c)  certification:  This  is the process in which a CA issues a
      certificate for a user's public key, and returns that certificate
      to the user's client system and/or posts that certificate in a
      repository.

      (d)  key pair recovery:  As an option, user client key materials
      (e.g., a user's private key used for encryption purposes) may be
      backed up by a CA or a key backup system.  If a user needs to
      recover these backed up key materials (e.g., as a result of a
      forgotten password or a lost key chain file), an on-line protocol
      exchange may be needed to support such recovery.

      (e)  key pair update:  All key pairs need to be updated regularly,
      i.e., replaced with a new key pair, and new certificates issued.

      (f)  revocation request:  An authorized person advises a CA of an
      abnormal situation requiring certificate revocation.

      (g)  cross-certification:  Two CAs exchange information used in
      establishing a cross-certificate. A cross-certificate is a
      certificate issued by one CA to another CA which contains a CA
      signature key used for issuing certificates.

   Note that on-line protocols are not the only way of implementing the
   above functions.  For all functions there are off-line methods of
   achieving the same result, and this specification does not mandate
   use of on-line protocols.  For example, when hardware tokens are
   used, many of the functions may be achieved as part of the physical
   token delivery.  Furthermore, some of the above functions may be
   combined into one protocol exchange.  In particular, two or more of
   the registration, initialization, and certification functions can be
   combined into one protocol exchange.

   The PKIX series of specifications may define a set of standard
   message formats supporting the above functions in future
   specifications.  In that case, the protocols for conveying these
   messages in different environments (e.g., on-line, file transfer, e-
   mail, and WWW) will also be described in those specifications.




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4  Certificate and Certificate Extensions Profile

   This section presents a profile for public key certificates that will
   foster interoperability and a reusable PKI.  This section is based
   upon the X.509 v3 certificate format and the standard certificate
   extensions defined in [X.509].  The ISO/IEC/ITU documents use the
   1993 version of ASN.1; while this document uses the 1988 ASN.1
   syntax, the encoded certificate and standard extensions are
   equivalent.  This section also defines private extensions required to
   support a PKI for the Internet community.

   Certificates may be used in a wide range of applications and
   environments covering a broad spectrum of interoperability goals and
   a broader spectrum of operational and assurance requirements.  The
   goal of this document is to establish a common baseline for generic
   applications requiring broad interoperability and limited special
   purpose requirements.  In particular, the emphasis will be on
   supporting the use of X.509 v3 certificates for informal Internet
   electronic mail, IPsec, and WWW applications.

4.1  Basic Certificate Fields

   The X.509 v3 certificate basic syntax is as follows.  For signature
   calculation, the certificate is encoded using the ASN.1 distinguished
   encoding rules (DER) [X.208].  ASN.1 DER encoding is a tag, length,
   value encoding system for each element.

   Certificate  ::=  SEQUENCE  {
        tbsCertificate       TBSCertificate,
        signatureAlgorithm   AlgorithmIdentifier,
        signatureValue       BIT STRING  }

   TBSCertificate  ::=  SEQUENCE  {
        version         [0]  EXPLICIT Version DEFAULT v1,
        serialNumber         CertificateSerialNumber,
        signature            AlgorithmIdentifier,
        issuer               Name,
        validity             Validity,
        subject              Name,
        subjectPublicKeyInfo SubjectPublicKeyInfo,
        issuerUniqueID  [1]  IMPLICIT UniqueIdentifier OPTIONAL,
                             -- If present, version shall be v2 or v3
        subjectUniqueID [2]  IMPLICIT UniqueIdentifier OPTIONAL,
                             -- If present, version shall be v2 or v3
        extensions      [3]  EXPLICIT Extensions OPTIONAL
                             -- If present, version shall be v3
        }




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   Version  ::=  INTEGER  {  v1(0), v2(1), v3(2)  }

   CertificateSerialNumber  ::=  INTEGER

   Validity ::= SEQUENCE {
        notBefore      Time,
        notAfter       Time }

   Time ::= CHOICE {
        utcTime        UTCTime,
        generalTime    GeneralizedTime }

   UniqueIdentifier  ::=  BIT STRING

   SubjectPublicKeyInfo  ::=  SEQUENCE  {
        algorithm            AlgorithmIdentifier,
        subjectPublicKey     BIT STRING  }

   Extensions  ::=  SEQUENCE SIZE (1..MAX) OF Extension

   Extension  ::=  SEQUENCE  {
        extnID      OBJECT IDENTIFIER,
        critical    BOOLEAN DEFAULT FALSE,
        extnValue   OCTET STRING  }

   The following items describe the X.509 v3 certificate for use in the
   Internet.

4.1.1  Certificate Fields

   The Certificate is a SEQUENCE of three required fields. The fields
   are described in detail in the following subsections.

4.1.1.1  tbsCertificate

   The field contains the names of the subject and issuer, a public key
   associated with the subject, a validity period, and other associated
   information.  The fields are described in detail in section 4.1.2;
   the tbscertificate may also include extensions which are described in
   section 4.2.

4.1.1.2  signatureAlgorithm

   The signatureAlgorithm field contains the identifier for the
   cryptographic algorithm used by the CA to sign this certificate.
   Section 7.2 lists the supported signature algorithms.

   An algorithm identifier is defined by the following ASN.1 structure:



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   AlgorithmIdentifier  ::=  SEQUENCE  {
        algorithm               OBJECT IDENTIFIER,
        parameters              ANY DEFINED BY algorithm OPTIONAL  }

   The algorithm identifier is used to identify a cryptographic
   algorithm.  The OBJECT IDENTIFIER component identifies the algorithm
   (such as DSA with SHA-1).  The contents of the optional parameters
   field will vary according to the algorithm identified. Section 7.2
   lists the supported algorithms for this specification.

   This field MUST contain the same algorithm identifier as the
   signature field in the sequence tbsCertificate (see sec. 4.1.2.3).

4.1.1.3  signatureValue

   The signatureValue field contains a digital signature computed upon
   the ASN.1 DER encoded tbsCertificate.  The ASN.1 DER encoded
   tbsCertificate is used as the input to the signature function. This
   signature value is then ASN.1 encoded as a BIT STRING and included in
   the Certificate's signature field. The details of this process are
   specified for each of the supported algorithms in Section 7.2.

   By generating this signature, a CA certifies the validity of the
   information in the tbsCertificate field.  In particular, the CA
   certifies the binding between the public key material and the subject
   of the certificate.

4.1.2  TBSCertificate

   The sequence TBSCertificate contains information associated with the
   subject of the certificate and the CA who issued it.  Every
   TBSCertificate contains the names of the subject and issuer, a public
   key associated with the subject, a validity period, a version number,
   and a serial number; some may contain optional unique identifier
   fields.  The remainder of this section describes the syntax and
   semantics of these fields.  A TBSCertificate may also include
   extensions.  Extensions for the Internet PKI are described in Section
   4.2.

4.1.2.1  Version

   This field describes the version of the encoded certificate.  When
   extensions are used, as expected in this profile, use X.509 version 3
   (value is 2).  If no extensions are present, but a UniqueIdentifier
   is present, use version 2 (value is 1).  If only basic fields are
   present, use version 1 (the value is omitted from the certificate as
   the default value).




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   Implementations SHOULD be prepared to accept any version certificate.
   At a minimum, conforming implementations MUST recognize version 3
   certificates.

   Generation of version 2 certificates is not expected by
   implementations based on this profile.

4.1.2.2  Serial number

   The serial number is an integer assigned by the CA to each
   certificate.  It MUST be unique for each certificate issued by a
   given CA (i.e., the issuer name and serial number identify a unique
   certificate).

4.1.2.3  Signature

   This field contains the algorithm identifier for the algorithm used
   by the CA to sign the certificate.

   This field MUST contain the same algorithm identifier as the
   signatureAlgorithm field in the sequence Certificate (see sec.
   4.1.1.2).  The contents of the optional parameters field will vary
   according to the algorithm identified.  Section 7.2 lists the
   supported signature algorithms.

4.1.2.4  Issuer

   The issuer field identifies the entity who has signed and issued the
   certificate.  The issuer field MUST contain a non-empty distinguished
   name (DN).  The issuer field is defined as the X.501 type Name.
   [X.501] Name is defined by the following ASN.1 structures:

   Name ::= CHOICE {
     RDNSequence }

   RDNSequence ::= SEQUENCE OF RelativeDistinguishedName

   RelativeDistinguishedName ::=
     SET OF AttributeTypeAndValue

   AttributeTypeAndValue ::= SEQUENCE {
     type     AttributeType,
     value    AttributeValue }

   AttributeType ::= OBJECT IDENTIFIER

   AttributeValue ::= ANY DEFINED BY AttributeType




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   DirectoryString ::= CHOICE {
         teletexString           TeletexString (SIZE (1..MAX)),
         printableString         PrintableString (SIZE (1..MAX)),
         universalString         UniversalString (SIZE (1..MAX)),
         utf8String              UTF8String (SIZE (1.. MAX)),
         bmpString               BMPString (SIZE (1..MAX)) }

   The Name describes a hierarchical name composed of attributes, such
   as country name, and corresponding values, such as US.  The type of
   the component AttributeValue is determined by the AttributeType; in
   general it will be a DirectoryString.

   The DirectoryString type is defined as a choice of PrintableString,
   TeletexString, BMPString, UTF8String, and UniversalString.  The
   UTF8String encoding is the preferred encoding, and all certificates
   issued after December 31, 2003 MUST use the UTF8String encoding of
   DirectoryString (except as noted below).  Until that date, conforming
   CAs MUST choose from the following options when creating a
   distinguished name, including their own:

      (a) if the character set is sufficient, the string MAY be
      represented as a PrintableString;

      (b) failing (a), if the BMPString character set is sufficient the
      string MAY be represented as a BMPString; and

      (c) failing (a) and (b), the string MUST be represented as a
      UTF8String.  If (a) or (b) is satisfied, the CA MAY still choose
      to represent the string as a UTF8String.

   Exceptions to the December 31, 2003 UTF8 encoding requirements are as
   follows:

      (a) CAs MAY issue "name rollover" certificates to support an
      orderly migration to UTF8String encoding.  Such certificates would
      include the CA's UTF8String encoded name as issuer and and the old
      name encoding as subject, or vice-versa.

      (b) As stated in section 4.1.2.6, the subject field MUST be
      populated with a non-empty distinguished name matching the
      contents of the issuer field in all certificates issued by the
      subject CA regardless of encoding.

   The TeletexString and UniversalString are included for backward
   compatibility, and should not be used for certificates for new
   subjects.  However, these types may be used in certificates where the
   name was previously established.  Certificate users SHOULD be
   prepared to receive certificates with these types.



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   In addition, many legacy implementations support names encoded in the
   ISO 8859-1 character set (Latin1String) but tag them as
   TeletexString.  The Latin1String includes characters used in Western
   European countries which are not part of the TeletexString charcter
   set.  Implementations that process TeletexString SHOULD be prepared
   to handle the entire ISO 8859-1 character set.[ISO 8859-1]

   As noted above, distinguished names are composed of attributes.  This
   specification does not restrict the set of attribute types that may
   appear in names.  However, conforming implementations MUST be
   prepared to receive certificates with issuer names containing the set
   of attribute types defined below.  This specification also recommends
   support for additional attribute types.

   Standard sets of attributes have been defined in the X.500 series of
   specifications.[X.520]  Implementations of this specification MUST be
   prepared to receive the following standard attribute types in issuer
   names: country, organization, organizational-unit, distinguished name
   qualifier, state or province name,  and common name (e.g., "Susan
   Housley").  In addition, implementations of this specification SHOULD
   be prepared to receive the following standard attribute types in
   issuer names: locality, title,  surname, given name, initials, and
   generation qualifier (e.g., "Jr.", "3rd", or "IV").  The syntax and
   associated object identifiers (OIDs) for these attribute types are
   provided in the ASN.1 modules in Appendices A and B.

   In addition, implementations of this specification MUST be prepared
   to receive the domainComponent attribute, as defined in [RFC 2247].
   The Domain (Nameserver) System (DNS) provides a hierarchical resource
   labeling system.  This attribute provides is a convenient mechanism
   for organizations that wish to use DNs that parallel their DNS names.
   This is not a replacement for the dNSName component of the
   alternative name field. Implementations are not required to convert
   such names into DNS names. The syntax and associated OID for this
   attribute type is provided in the ASN.1 modules in Appendices A and
   B.

   Certificate users MUST be prepared to process the issuer
   distinguished name and subject distinguished name (see sec. 4.1.2.6)
   fields to perform name chaining for certification path validation
   (see section 6). Name chaining is performed by matching the issuer
   distinguished name in one certificate with the subject name in a CA
   certificate.

   This specification requires only a subset of the name comparison
   functionality specified in the X.500 series of specifications.  The
   requirements for conforming implementations are as follows:




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      (a) attribute values encoded in different types (e.g.,
      PrintableString and BMPString) may be assumed to represent
      different strings;

      (b) attribute values in types other than PrintableString are case
      sensitive (this permits matching of attribute values as binary
      objects);

      (c) attribute values in PrintableString are not case sensitive
      (e.g., "Marianne Swanson" is the same as "MARIANNE SWANSON"); and

      (d) attribute values in PrintableString are compared after
      removing leading and trailing white space and converting internal
      substrings of one or more consecutive white space characters to a
      single space.

   These name comparison rules permit a certificate user to validate
   certificates issued using languages or encodings unfamiliar to the
   certificate user.

   In addition, implementations of this specification MAY use these
   comparison rules to process unfamiliar attribute types for name
   chaining. This allows implementations to process certificates with
   unfamiliar attributes in the issuer name.

   Note that the comparison rules defined in the X.500 series of
   specifications indicate that the character sets used to encode data
   in distinguished names are irrelevant.  The characters themselves are
   compared without regard to encoding. Implementations of the profile
   are permitted to use the comparison algorithm defined in the X.500
   series.  Such an implementation will recognize a superset of name
   matches recognized by the algorithm specified above.

4.1.2.5  Validity

   The certificate validity period is the time interval during which the
   CA warrants that it will maintain information about the status of the
   certificate. The field is represented as a SEQUENCE of two dates:
   the date on which the certificate validity period begins (notBefore)
   and the date on which the certificate validity period ends
   (notAfter).  Both notBefore and notAfter may be encoded as UTCTime or
   GeneralizedTime.

   CAs conforming to this profile MUST always encode certificate
   validity dates through the year 2049 as UTCTime; certificate validity
   dates in 2050 or later MUST be encoded as GeneralizedTime.





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4.1.2.5.1  UTCTime

   The universal time type, UTCTime, is a standard ASN.1 type intended
   for international applications where local time alone is not
   adequate.  UTCTime specifies the year through the two low order
   digits and time is specified to the precision of one minute or one
   second.  UTCTime includes either Z (for Zulu, or Greenwich Mean Time)
   or a time differential.

   For the purposes of this profile, UTCTime values MUST be expressed
   Greenwich Mean Time (Zulu) and MUST include seconds (i.e., times are
   YYMMDDHHMMSSZ), even where the number of seconds is zero.  Conforming
   systems MUST interpret the year field (YY) as follows:

      Where YY is greater than or equal to 50, the year shall be
      interpreted as 19YY; and

      Where YY is less than 50, the year shall be interpreted as 20YY.

4.1.2.5.2  GeneralizedTime

   The generalized time type, GeneralizedTime, is a standard ASN.1 type
   for variable precision representation of time.  Optionally, the
   GeneralizedTime field can include a representation of the time
   differential between local and Greenwich Mean Time.

   For the purposes of this profile, GeneralizedTime values MUST be
   expressed Greenwich Mean Time (Zulu) and MUST include seconds (i.e.,
   times are YYYYMMDDHHMMSSZ), even where the number of seconds is zero.
   GeneralizedTime values MUST NOT include fractional seconds.

4.1.2.6  Subject

   The subject field identifies the entity associated with the public
   key stored in the subject public key field.  The subject name may be
   carried in the subject field and/or the subjectAltName extension.  If
   the subject is a CA (e.g., the basic constraints extension, as
   discussed in 4.2.1.10, is present and the value of cA is TRUE,) then
   the subject field MUST be populated with a non-empty distinguished
   name matching the contents of the issuer field (see sec. 4.1.2.4) in
   all certificates issued by the subject CA.  If subject naming
   information is present only in the subjectAltName extension (e.g., a
   key bound only to an email address or URI), then the subject name
   MUST be an empty sequence and the subjectAltName extension MUST be
   critical.






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   Where it is non-empty, the subject field MUST contain an X.500
   distinguished name (DN). The DN MUST be unique for each subject
   entity certified by the one CA as defined by the issuer name field. A
   CA may issue more than one certificate with the same DN to the same
   subject entity.

   The subject name field is defined as the X.501 type Name.
   Implementation requirements for this field are those defined for the
   issuer field (see sec.  4.1.2.4).  When encoding attribute values of
   type DirectoryString, the encoding rules for the issuer field MUST be
   implemented.  Implementations of this specification MUST be prepared
   to receive subject names containing the attribute types required for
   the issuer field.  Implementations of this specification SHOULD be
   prepared to receive subject names containing the recommended
   attribute types for the issuer field.  The syntax and associated
   object identifiers (OIDs) for these attribute types are provided in
   the ASN.1 modules in Appendices A and B.  Implementations of this
   specification MAY use these comparison rules to process unfamiliar
   attribute types (i.e., for name chaining). This allows
   implementations to process certificates with unfamiliar attributes in
   the subject name.

   In addition, legacy implementations exist where an RFC 822 name is
   embedded in the subject distinguished name as an EmailAddress
   attribute.  The attribute value for EmailAddress is of type IA5String
   to permit inclusion of the character '@', which is not part of the
   PrintableString character set.  EmailAddress attribute values are not
   case sensitive (e.g., "fanfeedback@redsox.com" is the same as
   "FANFEEDBACK@REDSOX.COM").

   Conforming implementations generating new certificates with
   electronic mail addresses MUST use the rfc822Name in the subject
   alternative name field (see sec. 4.2.1.7) to describe such
   identities.  Simultaneous inclusion of the EmailAddress attribute in
   the subject distinguished name to support legacy implementations is
   deprecated but permitted.

4.1.2.7  Subject Public Key Info

   This field is used to carry the public key and identify the algorithm
   with which the key is used. The algorithm is identified using the
   AlgorithmIdentifier structure specified in section 4.1.1.2. The
   object identifiers for the supported algorithms and the methods for
   encoding the public key materials (public key and parameters) are
   specified in section 7.3.






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4.1.2.8  Unique Identifiers

   These fields may only appear if the version is 2 or 3 (see sec.
   4.1.2.1).  The subject and issuer unique identifiers are present in
   the certificate to handle the possibility of reuse of subject and/or
   issuer names over time.  This profile recommends that names not be
   reused for different entities and that Internet certificates not make
   use of unique identifiers.  CAs conforming to this profile SHOULD NOT
   generate certificates with unique identifiers.  Applications
   conforming to this profile SHOULD be capable of parsing unique
   identifiers and making comparisons.

4.1.2.9  Extensions

   This field may only appear if the version is 3 (see sec. 4.1.2.1).
   If present, this field is a SEQUENCE of one or more certificate
   extensions. The format and content of certificate extensions in the
   Internet PKI is defined in section 4.2.

4.2  Standard Certificate Extensions

   The extensions defined for X.509 v3 certificates provide methods for
   associating additional attributes with users or public keys and for
   managing the certification hierarchy.  The X.509 v3 certificate
   format also allows communities to define private extensions to carry
   information unique to those communities.  Each extension in a
   certificate may be designated as critical or non-critical.  A
   certificate using system MUST reject the certificate if it encounters
   a critical extension it does not recognize; however, a non-critical
   extension may be ignored if it is not recognized.  The following
   sections present recommended extensions used within Internet
   certificates and standard locations for information.  Communities may
   elect to use additional extensions; however, caution should be
   exercised in adopting any critical extensions in certificates which
   might prevent use in a general context.

   Each extension includes an OID and an ASN.1 structure.  When an
   extension appears in a certificate, the OID appears as the field
   extnID and the corresponding ASN.1 encoded structure is the value of
   the octet string extnValue.  Only one instance of a particular
   extension may appear in a particular certificate. For example, a
   certificate may contain only one authority key identifier extension
   (see sec. 4.2.1.1).  An extension includes the boolean critical, with
   a default value of FALSE.  The text for each extension specifies the
   acceptable values for the critical field.






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   Conforming CAs MUST support key identifiers (see sec. 4.2.1.1 and
   4.2.1.2), basic constraints (see sec. 4.2.1.10), key usage (see sec.
   4.2.1.3), and certificate policies (see sec. 4.2.1.5) extensions. If
   the CA issues certificates with an empty sequence for the subject
   field, the CA MUST support the subject alternative name extension
   (see sec. 4.2.1.7).  Support for the remaining extensions is
   OPTIONAL. Conforming CAs may support extensions that are not
   identified within this specification; certificate issuers are
   cautioned that marking such extensions as critical may inhibit
   interoperability.

   At a minimum, applications conforming to this profile MUST recognize
   the extensions which must or may be critical in this specification.
   These extensions are:  key usage (see sec. 4.2.1.3), certificate
   policies (see sec. 4.2.1.5), the subject alternative name (see sec.
   4.2.1.7), basic constraints (see sec. 4.2.1.10), name constraints
   (see sec. 4.2.1.11), policy constraints (see sec. 4.2.1.12), and
   extended key usage (see sec. 4.2.1.13).

   In addition, this profile RECOMMENDS application support for the
   authority and subject key identifier (see sec. 4.2.1.1 and 4.2.1.2)
   extensions.

4.2.1  Standard Extensions

   This section identifies standard certificate extensions defined in
   [X.509] for use in the Internet PKI.  Each extension is associated
   with an OID defined in [X.509].  These OIDs are members of the id-ce
   arc, which is defined by the following:

   id-ce   OBJECT IDENTIFIER ::=  {joint-iso-ccitt(2) ds(5) 29}

4.2.1.1  Authority Key Identifier

   The authority key identifier extension provides a means of
   identifying the public key corresponding to the private key used to
   sign a certificate. This extension is used where an issuer has
   multiple signing keys (either due to multiple concurrent key pairs or
   due to changeover).  The identification may be based on either the
   key identifier (the subject key identifier in the issuer's
   certificate) or on the issuer name and serial number.

   The keyIdentifier field of the authorityKeyIdentifier extension MUST
   be included in all certificates generated by conforming CAs to
   facilitate chain building.  There is one exception; where a CA
   distributes its public key in the form of a "self-signed"
   certificate, the authority key identifier may be omitted.  In this
   case, the subject and authority key identifiers would be identical.



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   The value of the keyIdentifier field SHOULD be derived from the
   public key used to verify the certificate's signature or a method
   that generates unique values.  Two common methods for generating key
   identifiers from the public key are described in (sec. 4.2.1.2). One
   common method for generating unique values isdescribed in (sec.
   4.2.1.2).  Where a key identifier has not been previously
   established, this specification recommends use of one of these
   methods for generating keyIdentifiers.

   This profile recommends support for the key identifier method by all
   certificate users.

   This extension MUST NOT be marked critical.

   id-ce-authorityKeyIdentifier OBJECT IDENTIFIER ::=  { id-ce 35 }

   AuthorityKeyIdentifier ::= SEQUENCE {
      keyIdentifier             [0] KeyIdentifier           OPTIONAL,
      authorityCertIssuer       [1] GeneralNames            OPTIONAL,
      authorityCertSerialNumber [2] CertificateSerialNumber OPTIONAL  }

   KeyIdentifier ::= OCTET STRING

4.2.1.2  Subject Key Identifier

   The subject key identifier extension provides a means of identifying
   certificates that contain a particular public key.

   To facilitate chain building, this extension MUST appear in all con-
   forming CA certificates, that is, all certificates including the
   basic constraints extension (see sec. 4.2.1.10) where the value of cA
   is TRUE.  The value of the subject key identifier MUST be the value
   placed in the key identifier field of the Authority Key Identifier
   extension (see sec. 4.2.1.1) of certificates issued by the subject of
   this certificate.

   For CA certificates, subject key identifiers SHOULD be derived from
   the public key or a method that generates unique values.  Two common
   methods for generating key identifiers from the public key are:

      (1) The keyIdentifier is composed of the 160-bit SHA-1 hash of the
      value of the BIT STRING subjectPublicKey (excluding the tag,
      length, and number of unused bits).

      (2) The keyIdentifier is composed of a four bit type field with
      the value 0100 followed by the least significant 60 bits of the
      SHA-1 hash of the value of the BIT STRING subjectPublicKey.




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   One common method for generating unique values is a monotomically
   increasing sequence of integers.

   For end entity certificates, the subject key identifier extension
   provides a means for identifying certificates containing the
   particular public key used in an application. Where an end entity has
   obtained multiple certificates, especially from multiple CAs, the
   subject key identifier provides a means to quickly identify the set
   of certificates containing a particular public key. To assist
   applications in identificiation the appropriate end entity
   certificate, this extension SHOULD be included in all end entity
   certificates.

   For end entity certificates, subject key identifiers SHOULD be
   derived from the public key.  Two common methods for generating key
   identifiers from the public key are identifed above.

   Where a key identifier has not been previously established, this
   specification recommends use of one of these methods for generating
   keyIdentifiers.

   This extension MUST NOT be marked critical.

   id-ce-subjectKeyIdentifier OBJECT IDENTIFIER ::=  { id-ce 14 }

   SubjectKeyIdentifier ::= KeyIdentifier

4.2.1.3  Key Usage

   The key usage extension defines the purpose (e.g., encipherment,
   signature, certificate signing) of the key contained in the
   certificate.  The usage restriction might be employed when a key that
   could be used for more than one operation is to be restricted.  For
   example, when an RSA key should be used only for signing, the
   digitalSignature and/or nonRepudiation bits would be asserted.
   Likewise, when an RSA key should be used only for key management, the
   keyEncipherment bit would be asserted. When used, this extension
   SHOULD be marked critical.

      id-ce-keyUsage OBJECT IDENTIFIER ::=  { id-ce 15 }

      KeyUsage ::= BIT STRING {
           digitalSignature        (0),
           nonRepudiation          (1),
           keyEncipherment         (2),
           dataEncipherment        (3),
           keyAgreement            (4),
           keyCertSign             (5),



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           cRLSign                 (6),
           encipherOnly            (7),
           decipherOnly            (8) }


   Bits in the KeyUsage type are used as follows:

      The digitalSignature bit is asserted when the subject public key
      is used with a digital signature mechanism to support security
      services other than non-repudiation (bit 1), certificate signing
      (bit 5), or revocation information signing (bit 6). Digital
      signature mechanisms are often used for entity authentication and
      data origin authentication with integrity.

      The nonRepudiation bit is asserted when the subject public key is
      used to verify digital signatures used to provide a non-
      repudiation service which protects against the signing entity
      falsely denying some action, excluding certificate or CRL signing.

      The keyEncipherment bit is asserted when the subject public key is
      used for key transport.  For example, when an RSA key is to be
      used for key management, then this bit shall asserted.

      The dataEncipherment bit is asserted when the subject public key
      is used for enciphering user data, other than cryptographic keys.

      The keyAgreement bit is asserted when the subject public key is
      used for key agreement.  For example, when a Diffie-Hellman key is
      to be used for key management, then this bit shall asserted.

      The keyCertSign bit is asserted when the subject public key is
      used for verifying a signature on certificates.  This bit may only
      be asserted in CA certificates.

      The cRLSign bit is asserted when the subject public key is used
      for verifying a signature on revocation information (e.g., a CRL).

      The meaning of the encipherOnly bit is undefined in the absence of
      the keyAgreement bit.  When the encipherOnly bit is asserted and
      the keyAgreement bit is also set, the subject public key may be
      used only for enciphering data while performing key agreement.

      The meaning of the decipherOnly bit is undefined in the absence of
      the keyAgreement bit.  When the decipherOnly bit is asserted and
      the keyAgreement bit is also set, the subject public key may be
      used only for deciphering data while performing key agreement.





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   This profile does not restrict the combinations of bits that may be
   set in an instantiation of the keyUsage extension.  However,
   appropriate values for keyUsage extensions for particular algorithms
   are specified in section 7.3.

4.2.1.4  Private Key Usage Period

   This profile recommends against the use of this extension.  CAs
   conforming to this profile MUST NOT generate certificates with
   critical private key usage period extensions.

   The private key usage period extension allows the certificate issuer
   to specify a different validity period for the private key than the
   certificate. This extension is intended for use with digital
   signature keys.  This extension consists of two optional components,
   notBefore and notAfter.  The private key associated with the
   certificate should not be used to sign objects before or after the
   times specified by the two components, respectively. CAs conforming
   to this profile MUST NOT generate certificates with private key usage
   period extensions unless at least one of the two components is
   present.

   Where used, notBefore and notAfter are represented as GeneralizedTime
   and MUST be specified and interpreted as defined in section
   4.1.2.5.2.

   id-ce-privateKeyUsagePeriod OBJECT IDENTIFIER ::=  { id-ce 16 }

   PrivateKeyUsagePeriod ::= SEQUENCE {
        notBefore       [0]     GeneralizedTime OPTIONAL,
        notAfter        [1]     GeneralizedTime OPTIONAL }

4.2.1.5  Certificate Policies

   The certificate policies extension contains a sequence of one or more
   policy information terms, each of which consists of an object
   identifier (OID) and optional qualifiers.  These policy information
   terms indicate the policy under which the certificate has been issued
   and the purposes for which the certificate may be used.  Optional
   qualifiers, which may be present, are not expected to change the
   definition of the policy.

   Applications with specific policy requirements are expected to have a
   list of those policies which they will accept and to compare the
   policy OIDs in the certificate to that list.  If this extension is
   critical, the path validation software MUST be able to interpret this
   extension (including the optional qualifier), or MUST reject the
   certificate.



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   To promote interoperability, this profile RECOMMENDS that policy
   information terms consist of only an OID.  Where an OID alone is
   insufficient, this profile strongly recommends that use of qualifiers
   be limited to those identified in this section.

   This specification defines two policy qualifier types for use by
   certificate policy writers and certificate issuers. The qualifier
   types are the CPS Pointer and User Notice qualifiers.

   The CPS Pointer qualifier contains a pointer to a Certification
   Practice Statement (CPS) published by the CA.  The pointer is in the
   form of a URI.

   User notice is intended for display to a relying party when a
   certificate is used.  The application software SHOULD display all
   user notices in all certificates of the certification path used,
   except that if a notice is duplicated only one copy need be
   displayed.  To prevent such duplication, this qualifier SHOULD only
   be present in end-entity certificates and CA certificates issued to
   other organizations.

   The user notice has two optional fields: the noticeRef field and the
   explicitText field.

      The noticeRef field, if used, names an organization and
      identifies, by number, a particular textual statement prepared by
      that organization.  For example, it might identify the
      organization "CertsRUs" and notice number 1.  In a typical
      implementation, the application software will have a notice file
      containing the current set of notices for CertsRUs; the
      application will extract the notice text from the file and display
      it.  Messages may be multilingual, allowing the software to select
      the particular language message for its own environment.

      An explicitText field includes the textual statement directly in
      the certificate.  The explicitText field is a string with a
      maximum size of 200 characters.

   If both the noticeRef and explicitText options are included in the
   one qualifier and if the application software can locate the notice
   text indicated by the noticeRef option then that text should be
   displayed; otherwise, the explicitText string should be displayed.

   id-ce-certificatePolicies OBJECT IDENTIFIER ::=  { id-ce 32 }

   certificatePolicies ::= SEQUENCE SIZE (1..MAX) OF PolicyInformation





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   PolicyInformation ::= SEQUENCE {
        policyIdentifier   CertPolicyId,
        policyQualifiers   SEQUENCE SIZE (1..MAX) OF
                                PolicyQualifierInfo OPTIONAL }

   CertPolicyId ::= OBJECT IDENTIFIER

   PolicyQualifierInfo ::= SEQUENCE {
        policyQualifierId  PolicyQualifierId,
        qualifier          ANY DEFINED BY policyQualifierId }

   -- policyQualifierIds for Internet policy qualifiers

   id-qt          OBJECT IDENTIFIER ::=  { id-pkix 2 }
   id-qt-cps      OBJECT IDENTIFIER ::=  { id-qt 1 }
   id-qt-unotice  OBJECT IDENTIFIER ::=  { id-qt 2 }

   PolicyQualifierId ::=
        OBJECT IDENTIFIER ( id-qt-cps | id-qt-unotice )

   Qualifier ::= CHOICE {
        cPSuri           CPSuri,
        userNotice       UserNotice }

   CPSuri ::= IA5String

   UserNotice ::= SEQUENCE {
        noticeRef        NoticeReference OPTIONAL,
        explicitText     DisplayText OPTIONAL}

   NoticeReference ::= SEQUENCE {
        organization     DisplayText,
        noticeNumbers    SEQUENCE OF INTEGER }

   DisplayText ::= CHOICE {
        visibleString    VisibleString  (SIZE (1..200)),
        bmpString        BMPString      (SIZE (1..200)),
        utf8String       UTF8String     (SIZE (1..200)) }

4.2.1.6  Policy Mappings

   This extension is used in CA certificates.  It lists one or more
   pairs of OIDs; each pair includes an issuerDomainPolicy and a
   subjectDomainPolicy. The pairing indicates the issuing CA considers
   its issuerDomainPolicy equivalent to the subject CA's
   subjectDomainPolicy.





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   The issuing CA's users may accept an issuerDomainPolicy for certain
   applications. The policy mapping tells the issuing CA's users which
   policies associated with the subject CA are comparable to the policy
   they accept.

   This extension may be supported by CAs and/or applications, and it
   MUST be non-critical.

   id-ce-policyMappings OBJECT IDENTIFIER ::=  { id-ce 33 }

   PolicyMappings ::= SEQUENCE SIZE (1..MAX) OF SEQUENCE {
        issuerDomainPolicy      CertPolicyId,
        subjectDomainPolicy     CertPolicyId }

4.2.1.7  Subject Alternative Name

   The subject alternative names extension allows additional identities
   to be bound to the subject of the certificate.  Defined options
   include an Internet electronic mail address, a DNS name, an IP
   address, and a uniform resource identifier (URI).  Other options
   exist, including completely local definitions.  Multiple name forms,
   and multiple instances of each name form, may be included.  Whenever
   such identities are to be bound into a certificate, the subject
   alternative name (or issuer alternative name) extension MUST be used.

   Because the subject alternative name is considered to be
   definitiviely bound to the public key, all parts of the subject
   alternative name MUST be verified by the CA.

   Further, if the only subject identity included in the certificate is
   an alternative name form (e.g., an electronic mail address), then the
   subject distinguished name MUST be empty (an empty sequence), and the
   subjectAltName extension MUST be present. If the subject field
   contains an empty sequence, the subjectAltName extension MUST be
   marked critical.

   When the subjectAltName extension contains an Internet mail address,
   the address MUST be included as an rfc822Name. The format of an
   rfc822Name is an "addr-spec" as defined in RFC 822 [RFC 822]. An
   addr-spec has the form "local-part@domain". Note that an addr-spec
   has no phrase (such as a common name) before it, has no comment (text
   surrounded in parentheses) after it, and is not surrounded by "<" and
   ">". Note that while upper and lower case letters are allowed in an
   RFC 822 addr-spec, no significance is attached to the case.

   When the subjectAltName extension contains a iPAddress, the address
   MUST be stored in the octet string in "network byte order," as
   specified in RFC 791 [RFC 791]. The least significant bit (LSB) of



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   each octet is the LSB of the corresponding byte in the network
   address. For IP Version 4, as specified in RFC 791, the octet string
   MUST contain exactly four octets.  For IP Version 6, as specified in
   RFC 1883, the octet string MUST contain exactly sixteen octets [RFC
   1883].

   When the subjectAltName extension contains a domain name service
   label, the domain name MUST be stored in the dNSName (an IA5String).
   The name MUST be in the "preferred name syntax," as specified by RFC
   1034 [RFC 1034]. Note that while upper and lower case letters are
   allowed in domain names, no signifigance is attached to the case.  In
   addition, while the string " " is a legal domain name, subjectAltName
   extensions with a dNSName " " are not permitted.  Finally, the use of
   the DNS representation for Internet mail addresses (wpolk.nist.gov
   instead of wpolk@nist.gov) is not permitted; such identities are to
   be encoded as rfc822Name.

   When the subjectAltName extension contains a URI, the name MUST be
   stored in the uniformResourceIdentifier (an IA5String). The name MUST
   be a non-relative URL, and MUST follow the URL syntax and encoding
   rules specified in [RFC 1738].  The name must include both a scheme
   (e.g., "http" or "ftp") and a scheme-specific-part.  The scheme-
   specific-part must include a fully qualified domain name or IP
   address as the host.

   As specified in [RFC 1738], the scheme name is not case-sensitive
   (e.g., "http" is equivalent to "HTTP").  The host part is also not
   case-sensitive, but other components of the scheme-specific-part may
   be case-sensitive. When comparing URIs, conforming implementations
   MUST compare the scheme and host without regard to case, but assume
   the remainder of the scheme-specific-part is case sensitive.

   Subject alternative names may be constrained in the same manner as
   subject distinguished names using the name constraints extension as
   described in section 4.2.1.11.

   If the subjectAltName extension is present, the sequence MUST contain
   at least one entry.  Unlike the subject field, conforming CAs MUST
   NOT issue certificates with subjectAltNames containing empty
   GeneralName fields. For example, an rfc822Name is represented as an
   IA5String. While an empty string is a valid IA5String, such an
   rfc822Name is not permitted by this profile.  The behavior of clients
   that encounter such a certificate when processing a certificication
   path is not defined by this profile.







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   Finally, the semantics of subject alternative names that include
   wildcard characters (e.g., as a placeholder for a set of names) are
   not addressed by this specification.  Applications with specific
   requirements may use such names but shall define the semantics.


      id-ce-subjectAltName OBJECT IDENTIFIER ::=  { id-ce 17 }

      SubjectAltName ::= GeneralNames

      GeneralNames ::= SEQUENCE SIZE (1..MAX) OF GeneralName

      GeneralName ::= CHOICE {
           otherName                       [0]     OtherName,
           rfc822Name                      [1]     IA5String,
           dNSName                         [2]     IA5String,
           x400Address                     [3]     ORAddress,
           directoryName                   [4]     Name,
           ediPartyName                    [5]     EDIPartyName,
           uniformResourceIdentifier       [6]     IA5String,
           iPAddress                       [7]     OCTET STRING,
           registeredID                    [8]     OBJECT IDENTIFIER}

      OtherName ::= SEQUENCE {
           type-id    OBJECT IDENTIFIER,
           value      [0] EXPLICIT ANY DEFINED BY type-id }

      EDIPartyName ::= SEQUENCE {
           nameAssigner            [0]     DirectoryString OPTIONAL,
           partyName               [1]     DirectoryString }

4.2.1.8  Issuer Alternative Names

   As with 4.2.1.7, this extension is used to associate Internet style
   identities with the certificate issuer. Issuer alternative names MUST
   be encoded as in 4.2.1.7.

   Where present, this extension SHOULD NOT be marked critical.

      id-ce-issuerAltName OBJECT IDENTIFIER ::=  { id-ce 18 }

      IssuerAltName ::= GeneralNames

4.2.1.9  Subject Directory Attributes

   The subject directory attributes extension is not recommended as an
   essential part of this profile, but it may be used in local
   environments.  This extension MUST be non-critical.



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   id-ce-subjectDirectoryAttributes OBJECT IDENTIFIER ::=  { id-ce 9 }

   SubjectDirectoryAttributes ::= SEQUENCE SIZE (1..MAX) OF Attribute

4.2.1.10  Basic Constraints

   The basic constraints extension identifies whether the subject of the
   certificate is a CA and how deep a certification path may exist
   through that CA.

   The pathLenConstraint field is meaningful only if cA is set to TRUE.
   In this case, it gives the maximum number of CA certificates that may
   follow this certificate in a certification path. A value of zero
   indicates that only an end-entity certificate may follow in the path.
   Where it appears, the pathLenConstraint field MUST be greater than or
   equal to zero. Where pathLenConstraint does not appear, there is no
   limit to the allowed length of the certification path.

   This extension MUST appear as a critical extension in all CA
   certificates.  This extension SHOULD NOT appear in end entity
   certificates.

   id-ce-basicConstraints OBJECT IDENTIFIER ::=  { id-ce 19 }

   BasicConstraints ::= SEQUENCE {
        cA                      BOOLEAN DEFAULT FALSE,
        pathLenConstraint       INTEGER (0..MAX) OPTIONAL }

4.2.1.11  Name Constraints

   The name constraints extension, which MUST be used only in a CA
   certificate, indicates a name space within which all subject names in
   subsequent certificates in a certification path shall be located.
   Restrictions may apply to the subject distinguished name or subject
   alternative names.  Restrictions apply only when the specified name
   form is present. If no name of the type is in the certificate, the
   certificate is acceptable.

   Restrictions are defined in terms of permitted or excluded name
   subtrees.  Any name matching a restriction in the excludedSubtrees
   field is invalid regardless of information appearing in the
   permittedSubtrees.  This extension MUST be critical.

   Within this profile, the minimum and maximum fields are not used with
   any name forms, thus minimum is always zero, and maximum is always
   absent.





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   For URIs, the constraint applies to the host part of the name. The
   constraint may specify a host or a domain.  Examples would be
   "foo.bar.com";  and ".xyz.com".  When the the constraint begins with
   a period, it may be expanded with one or more subdomains.  That is,
   the constraint ".xyz.com" is satisfied by both abc.xyz.com and
   abc.def.xyz.com.  However, the constraint ".xyz.com" is not satisfied
   by "xyz.com".  When the constraint does not begin with a period, it
   specifies a host.

   A name constraint for Internat mail addresses may specify a
   particular mailbox, all addresses at a particular host, or all
   mailboxes in a domain.  To indicate a particular mailbox, the
   constraint is the complete mail address.  For example, "root@xyz.com"
   indicates the root mailbox on the host "xyz.com". To indicate all
   Internet mail addresses on a particular host, the constraint is
   specified as the host name.  For example, the constraint "xyz.com" is
   satisfied by any mail address at the host "xyz.com". To specify any
   address within a domain, the constraint is specified with a leading
   period (as with URIs).  For example, ".xyz.com" indicates all the
   Internet mail addresses in the domain "xyz.com", but Internet mail
   addresses on the host "xyz.com".

   DNS name restrictions are expressed as foo.bar.com. Any subdomain
   satisfies the name constraint. For example, www.foo.bar.com would
   satisfy the constraint but bigfoo.bar.com would not.

   Legacy implementations exist where an RFC 822 name is embedded in the
   subject distinguished name in an attribute of type EmailAddress (see
   sec. 4.1.2.6). When rfc822 names are constrained, but the certificate
   does not include a subject alternative name, the rfc822 name
   constraint MUST be applied to the attribute of type EmailAddress in
   the subject distinguished name.  The ASN.1 syntax for EmailAddress
   and the corresponding OID are supplied in Appendix A and B.

   Restrictions of the form directoryName MUST be applied to the subject
   field in the certificate and to the subjectAltName extensions of type
   directoryName. Restrictions of the form x400Address MUST be applied
   to subjectAltName extensions of type x400Address.

   When applying restrictions of the form directoryName, an
   implementation MUST compare DN attributes.  At a minimum,
   implementations MUST perform the DN comparison rules specified in
   Section 4.1.2.4.  CAs issuing certificates with a restriction of the
   form directoryName SHOULD NOT rely on implementation of the full ISO
   DN name comparison algorithm.  This implies name restrictions shall
   be stated identically to the encoding used in the subject field or
   subjectAltName extension.




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   The syntax of iPAddress MUST be as described in section 4.2.1.7 with
   the following additions specifically for Name Constraints.  For IPv4
   addresses, the ipAddress field of generalName MUST contain eight (8)
   octets, encoded in the style of RFC 1519 (CIDR) to represent an
   address range.[RFC 1519]  For IPv6 addresses, the ipAddress field
   MUST contain 32 octets similarly encoded.  For example, a name
   constraint for "class C" subnet 10.9.8.0 shall be represented as the
   octets 0A 09 08 00 FF FF FF 00, representing the CIDR notation
   10.9.8.0/255.255.255.0.

   The syntax and semantics for name constraints for otherName,
   ediPartyName, and registeredID are not defined by this specification.

      id-ce-nameConstraints OBJECT IDENTIFIER ::=  { id-ce 30 }

      NameConstraints ::= SEQUENCE {
           permittedSubtrees       [0]     GeneralSubtrees OPTIONAL,
           excludedSubtrees        [1]     GeneralSubtrees OPTIONAL }

      GeneralSubtrees ::= SEQUENCE SIZE (1..MAX) OF GeneralSubtree

      GeneralSubtree ::= SEQUENCE {
           base                    GeneralName,
           minimum         [0]     BaseDistance DEFAULT 0,
           maximum         [1]     BaseDistance OPTIONAL }

      BaseDistance ::= INTEGER (0..MAX)

4.2.1.12  Policy Constraints

   The policy constraints extension can be used in certificates issued
   to CAs. The policy constraints extension constrains path validation
   in two ways. It can be used to prohibit policy mapping or require
   that each certificate in a path contain an acceptable policy
   identifier.

   If the inhibitPolicyMapping field is present, the value indicates the
   number of additional certificates that may appear in the path before
   policy mapping is no longer permitted.  For example, a value of one
   indicates that policy mapping may be processed in certificates issued
   by the subject of this certificate, but not in additional
   certificates in the path.

   If the requireExplicitPolicy field is present, subsequent
   certificates shall include an acceptable policy identifier. The value
   of requireExplicitPolicy indicates the number of additional
   certificates that may appear in the path before an explicit policy is
   required.  An acceptable policy identifier is the identifier of a



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   policy required by the user of the certification path or the
   identifier of a policy which has been declared equivalent through
   policy mapping.

   Conforming CAs MUST NOT issue certificates where policy constraints
   is a null sequence. That is, at least one of the inhibitPolicyMapping
   field or the requireExplicitPolicy field MUST be present. The
   behavior of clients that encounter a null policy constraints field is
   not addressed in this profile.

   This extension may be critical or non-critical.

   id-ce-policyConstraints OBJECT IDENTIFIER ::=  { id-ce 36 }

   PolicyConstraints ::= SEQUENCE {
        requireExplicitPolicy           [0] SkipCerts OPTIONAL,
        inhibitPolicyMapping            [1] SkipCerts OPTIONAL }

   SkipCerts ::= INTEGER (0..MAX)

4.2.1.13  Extended key usage field

   This field indicates one or more purposes for which the certified
   public key may be used, in addition to or in place of the basic
   purposes indicated in the key usage extension field.  This field is
   defined as follows:

   id-ce-extKeyUsage OBJECT IDENTIFIER ::= {id-ce 37}

   ExtKeyUsageSyntax ::= SEQUENCE SIZE (1..MAX) OF KeyPurposeId

   KeyPurposeId ::= OBJECT IDENTIFIER

   Key purposes may be defined by any organization with a need. Object
   identifiers used to identify key purposes shall be assigned in
   accordance with IANA or ITU-T Rec. X.660 | ISO/IEC/ITU 9834-1.

   This extension may, at the option of the certificate issuer, be
   either critical or non-critical.

   If the extension is flagged critical, then the certificate MUST be
   used only for one of the purposes indicated.

   If the extension is flagged non-critical, then it indicates the
   intended purpose or purposes of the key, and may be used in finding
   the correct key/certificate of an entity that has multiple
   keys/certificates. It is an advisory field and does not imply that
   usage of the key is restricted by the certification authority to the



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   purpose indicated. Certificate using applications may nevertheless
   require that a particular purpose be indicated in order for the
   certificate to be acceptable to that application.

   If a certificate contains both a critical key usage field and a
   critical extended key usage field, then both fields MUST be processed
   independently and the certificate MUST only be used for a purpose
   consistent with both fields.  If there is no purpose consistent with
   both fields, then the certificate MUST NOT be used for any purpose.

   The following key usage purposes are defined by this profile:

   id-kp OBJECT IDENTIFIER ::= { id-pkix 3 }

   id-kp-serverAuth              OBJECT IDENTIFIER ::=   {id-kp 1}
   -- TLS Web server authentication
   -- Key usage bits that may be consistent: digitalSignature,
   --                         keyEncipherment or keyAgreement
   --
   id-kp-clientAuth              OBJECT IDENTIFIER ::=   {id-kp 2}
   -- TLS Web client authentication
   -- Key usage bits that may be consistent: digitalSignature and/or
   --                            keyAgreement
   --
   id-kp-codeSigning             OBJECT IDENTIFIER ::=   {id-kp 3}
   -- Signing of downloadable executable code
   -- Key usage bits that may be consistent: digitalSignature
   --
   id-kp-emailProtection         OBJECT IDENTIFIER ::=   {id-kp 4}
   -- E-mail protection
   -- Key usage bits that may be consistent: digitalSignature,
   --                         nonRepudiation, and/or (keyEncipherment
   --                         or keyAgreement)
   --
   id-kp-timeStamping    OBJECT IDENTIFIER ::= { id-kp 8 }
   -- Binding the hash of an object to a time from an agreed-upon time
   -- source. Key usage bits that may be consistent: digitalSignature,
   --                         nonRepudiation

4.2.1.14  CRL Distribution Points

   The CRL distribution points extension identifies how CRL information
   is obtained.  The extension SHOULD be non-critical, but this profile
   recommends support for this extension by CAs and applications.
   Further discussion of CRL management is contained in section 5.






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   If the cRLDistributionPoints extension contains a
   DistributionPointName of type URI, the following semantics MUST be
   assumed: the URI is a pointer to the current CRL for the associated
   reasons and will be issued by the associated cRLIssuer.  The expected
   values for the URI are those defined in 4.2.1.7. Processing rules for
   other values are not defined by this specification.  If the
   distributionPoint omits reasons, the CRL MUST include revocations for
   all reasons. If the distributionPoint omits cRLIssuer, the CRL MUST
   be issued by the CA that issued the certificate.

   id-ce-cRLDistributionPoints OBJECT IDENTIFIER ::=  { id-ce 31 }

   cRLDistributionPoints ::= {
        CRLDistPointsSyntax }

   CRLDistPointsSyntax ::= SEQUENCE SIZE (1..MAX) OF DistributionPoint

   DistributionPoint ::= SEQUENCE {
        distributionPoint       [0]     DistributionPointName OPTIONAL,
        reasons                 [1]     ReasonFlags OPTIONAL,
        cRLIssuer               [2]     GeneralNames OPTIONAL }

   DistributionPointName ::= CHOICE {
        fullName                [0]     GeneralNames,
        nameRelativeToCRLIssuer [1]     RelativeDistinguishedName }

   ReasonFlags ::= BIT STRING {
        unused                  (0),
        keyCompromise           (1),
        cACompromise            (2),
        affiliationChanged      (3),
        superseded              (4),
        cessationOfOperation    (5),
        certificateHold         (6) }

4.2.2  Private Internet Extensions

   This section defines one new extension for use in the Internet Public
   Key Infrastructure.  This extension may be used to direct
   applications to identify an on-line validation service supporting the
   issuing CA.  As the information may be available in multiple forms,
   each extension is a sequence of IA5String values, each of which
   represents a URI.  The URI implicitly specifies the location and
   format of the information and the method for obtaining the
   information.






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   An object identifier is defined for the private extension.  The
   object identifier associated with the private extension is defined
   under the arc id-pe within the id-pkix name space.  Any future
   extensions defined for the Internet PKI will also be defined under
   the arc id-pe.

      id-pkix  OBJECT IDENTIFIER  ::=
               { iso(1) identified-organization(3) dod(6) internet(1)
                       security(5) mechanisms(5) pkix(7) }

      id-pe  OBJECT IDENTIFIER  ::=  { id-pkix 1 }

4.2.2.1  Authority Information Access

   The authority information access extension indicates how to access CA
   information and services for the issuer of the certificate in which
   the extension appears. Information and services may include on-line
   validation services and CA policy data.  (The location of CRLs is not
   specified in this extension; that information is provided by the
   cRLDistributionPoints extension.)  This extension may be included in
   subject or CA certificates, and it MUST be non-critical.

   id-pe-authorityInfoAccess OBJECT IDENTIFIER ::= { id-pe 1 }

   AuthorityInfoAccessSyntax  ::=
           SEQUENCE SIZE (1..MAX) OF AccessDescription

   AccessDescription  ::=  SEQUENCE {
           accessMethod          OBJECT IDENTIFIER,
           accessLocation        GeneralName  }

   id-ad OBJECT IDENTIFIER ::= { id-pkix 48 }

   id-ad-caIssuers OBJECT IDENTIFIER ::= { id-ad 2 }

   Each entry in the sequence AuthorityInfoAccessSyntax describes the
   format and location of additional information about the CA who issued
   the certificate in which this extension appears.  The type and format
   of the information is specified by the accessMethod field; the
   accessLocation field specifies the location of the information.  The
   retrieval mechanism may be implied by the accessMethod or specified
   by accessLocation.

   This profile defines one OID for accessMethod. The id-ad-caIssuers
   OID is used when the additional information lists CAs that have
   issued certificates superior to the CA that issued the certificate





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   containing this extension.  The referenced CA Issuers description is
   intended to aid certificate users in the selection of a certification
   path that terminates at a point trusted by the certificate user.

   When id-ad-caIssuers appears as accessInfoType, the accessLocation
   field describes the referenced description server and the access
   protocol to obtain the referenced description.  The accessLocation
   field is defined as a GeneralName, which can take several forms.
   Where the information is available via http, ftp, or ldap,
   accessLocation MUST be a uniformResourceIdentifier.  Where the
   information is available via the directory access protocol (dap),
   accessLocation MUST be a directoryName. When the information is
   available via electronic mail, accessLocation MUST be an rfc822Name.
   The semantics of other name forms of accessLocation (when
   accessMethod is id-ad-caIssuers) are not defined by this
   specification.

   Additional access descriptors may be defined in other PKIX
   specifications.

5  CRL and CRL Extensions Profile

   As described above, one goal of this X.509 v2 CRL profile is to
   foster the creation of an interoperable and reusable Internet PKI.
   To achieve this goal, guidelines for the use of extensions are
   specified, and some assumptions are made about the nature of
   information included in the CRL.

   CRLs may be used in a wide range of applications and environments
   covering a broad spectrum of interoperability goals and an even
   broader spectrum of operational and assurance requirements.  This
   profile establishes a common baseline for generic applications
   requiring broad interoperability.  The profile defines a baseline set
   of information that can be expected in every CRL.  Also, the profile
   defines common locations within the CRL for frequently used
   attributes as well as common representations for these attributes.

   This profile does not define any private Internet CRL extensions or
   CRL entry extensions.

   Environments with additional or special purpose requirements may
   build on this profile or may replace it.

   Conforming CAs are not required to issue CRLs if other revocation or
   certificate status mechanisms are provided.  Conforming CAs that
   issue CRLs MUST issue version 2 CRLs, and CAs MUST include the date
   by which the next CRL will be issued in the nextUpdate field (see




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   sec. 5.1.2.5), the CRL number extension (see sec. 5.2.3) and the
   authority key identifier extension (see sec. 5.2.1).  Conforming
   applications are required to process version 1 and 2 CRLs.

5.1  CRL Fields

   The X.509 v2 CRL syntax is as follows.  For signature calculation,
   the data that is to be signed is ASN.1 DER encoded.  ASN.1 DER
   encoding is a tag, length, value encoding system for each element.

   CertificateList  ::=  SEQUENCE  {
        tbsCertList          TBSCertList,
        signatureAlgorithm   AlgorithmIdentifier,
        signatureValue       BIT STRING  }

   TBSCertList  ::=  SEQUENCE  {
        version                 Version OPTIONAL,
                                     -- if present, shall be v2
        signature               AlgorithmIdentifier,
        issuer                  Name,
        thisUpdate              Time,
        nextUpdate              Time OPTIONAL,
        revokedCertificates     SEQUENCE OF SEQUENCE  {
             userCertificate         CertificateSerialNumber,
             revocationDate          Time,
             crlEntryExtensions      Extensions OPTIONAL
                                           -- if present, shall be v2
                                  }  OPTIONAL,
        crlExtensions           [0]  EXPLICIT Extensions OPTIONAL
                                           -- if present, shall be v2
                                  }

   -- Version, Time, CertificateSerialNumber, and Extensions
   -- are all defined in the ASN.1 in section 4.1

   -- AlgorithmIdentifier is defined in section 4.1.1.2

   The following items describe the use of the X.509 v2 CRL in the
   Internet PKI.

5.1.1  CertificateList Fields

   The CertificateList is a SEQUENCE of three required fields. The
   fields are described in detail in the following subsections.







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5.1.1.1  tbsCertList

   The first field in the sequence is the tbsCertList.  This field is
   itself a sequence containing the name of the issuer, issue date,
   issue date of the next list, the list of revoked certificates, and
   optional CRL extensions.  Further, each entry on the revoked
   certificate list is defined by a sequence of user certificate serial
   number, revocation date, and optional CRL entry extensions.

5.1.1.2  signatureAlgorithm

   The signatureAlgorithm field contains the algorithm identifier for
   the algorithm used by the CA to sign the CertificateList.  The field
   is of type AlgorithmIdentifier, which is defined in section 4.1.1.2.
   Section 7.2 lists the supported algorithms for this specification.
   Conforming CAs MUST use the algorithm identifiers presented in
   section 7.2 when signing with a supported signature algorithm.

   This field MUST contain the same algorithm identifier as the
   signature field in the sequence tbsCertList (see sec. 5.1.2.2).

5.1.1.3  signatureValue

   The signatureValue field contains a digital signature computed upon
   the ASN.1 DER encoded tbsCertList.  The ASN.1 DER encoded tbsCertList
   is used as the input to the signature function. This signature value
   is then ASN.1 encoded as a BIT STRING and included in the CRL's
   signatureValue field. The details of this process are specified for
   each of the supported algorithms in section 7.2.

5.1.2  Certificate List "To Be Signed"

   The certificate list to be signed, or TBSCertList, is a SEQUENCE of
   required and optional fields.  The required fields identify the CRL
   issuer, the algorithm used to sign the CRL, the date and time the CRL
   was issued, and the date and time by which the CA will issue the next
   CRL.

   Optional fields include lists of revoked certificates and CRL
   extensions.  The revoked certificate list is optional to support the
   case where a CA has not revoked any unexpired certificates that it
   has issued.  The profile requires conforming CAs to use the CRL
   extension cRLNumber in all CRLs issued.








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5.1.2.1  Version

   This optional field describes the version of the encoded CRL.  When
   extensions are used, as required by this profile, this field MUST be
   present and MUST specify version 2 (the integer value is 1).

5.1.2.2  Signature

   This field contains the algorithm identifier for the algorithm used
   to sign the CRL.  Section 7.2 lists OIDs for the most popular
   signature algorithms used in the Internet PKI.

   This field MUST contain the same algorithm identifier as the
   signatureAlgorithm field in the sequence CertificateList (see section
   5.1.1.2).

5.1.2.3  Issuer Name

   The issuer name identifies the entity who has signed and issued the
   CRL.  The issuer identity is carried in the issuer name field.
   Alternative name forms may also appear in the issuerAltName extension
   (see sec. 5.2.2).  The issuer name field MUST contain an X.500
   distinguished name (DN).  The issuer name field is defined as the
   X.501 type Name, and MUST follow the encoding rules for the issuer
   name field in the certificate (see sec. 4.1.2.4).

5.1.2.4  This Update

   This field indicates the issue date of this CRL. ThisUpdate may be
   encoded as UTCTime or GeneralizedTime.

   CAs conforming to this profile that issue CRLs MUST encode thisUpdate
   as UTCTime for dates through the year 2049. CAs conforming to this
   profile that issue CRLs MUST encode thisUpdate as GeneralizedTime for
   dates in the year 2050 or later.

   Where encoded as UTCTime, thisUpdate MUST be specified and
   interpreted as defined in section 4.1.2.5.1.  Where encoded as
   GeneralizedTime, thisUpdate MUST be specified and interpreted as
   defined in section 4.1.2.5.2.

5.1.2.5  Next Update

   This field indicates the date by which the next CRL will be issued.
   The next CRL could be issued before the indicated date, but it will
   not be issued any later than the indicated date. CAs SHOULD issue
   CRLs with a nextUpdate time equal to or later than all previous CRLs.
   nextUpdate may be encoded as UTCTime or GeneralizedTime.



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   This profile requires inclusion of nextUpdate in all CRLs issued by
   conforming CAs. Note that the ASN.1 syntax of TBSCertList describes
   this field as OPTIONAL, which is consistent with the ASN.1 structure
   defined in [X.509]. The behavior of clients processing CRLs which
   omit nextUpdate is not specified by this profile.

   CAs conforming to this profile that issue CRLs MUST encode nextUpdate
   as UTCTime for dates through the year 2049. CAs conforming to this
   profile that issue CRLs MUST encode nextUpdate as GeneralizedTime for
   dates in the year 2050 or later.

   Where encoded as UTCTime, nextUpdate MUST be specified and
   interpreted as defined in section 4.1.2.5.1.  Where encoded as
   GeneralizedTime, nextUpdate MUST be specified and interpreted as
   defined in section 4.1.2.5.2.

5.1.2.6  Revoked Certificates

   Revoked certificates are listed.  The revoked certificates are named
   by their serial numbers.  Certificates revoked by the CA are uniquely
   identified by the certificate serial number.  The date on which the
   revocation occurred is specified.  The time for revocationDate MUST
   be expressed as described in section 5.1.2.4. Additional information
   may be supplied in CRL entry extensions; CRL entry extensions are
   discussed in section 5.3.

5.1.2.7  Extensions

   This field may only appear if the version is 2 (see sec. 5.1.2.1).
   If present, this field is a SEQUENCE of one or more CRL extensions.
   CRL extensions are discussed in section 5.2.

5.2  CRL Extensions

   The extensions defined by ANSI X9 and ISO/IEC/ITU for X.509 v2 CRLs
   [X.509] [X9.55] provide methods for associating additional attributes
   with CRLs.  The X.509 v2 CRL format also allows communities to define
   private extensions to carry information unique to those communities.
   Each extension in a CRL may be designated as critical or non-
   critical.  A CRL validation MUST fail if it encounters a critical
   extension which it does not know how to process.  However, an
   unrecognized non-critical extension may be ignored.  The following
   subsections present those extensions used within Internet CRLs.
   Communities may elect to include extensions in CRLs which are not
   defined in this specification. However, caution should be exercised
   in adopting any critical extensions in CRLs which might be used in a
   general context.




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   Conforming CAs that issue CRLs are required to include the authority
   key identifier (see sec. 5.2.1) and the CRL number (see sec. 5.2.3)
   extensions in all CRLs issued.

5.2.1  Authority Key Identifier

   The authority key identifier extension provides a means of
   identifying the public key corresponding to the private key used to
   sign a CRL.  The identification can be based on either the key
   identifier (the subject key identifier in the CRL signer's
   certificate) or on the issuer name and serial number. This extension
   is especially useful where an issuer has more than one signing key,
   either due to multiple concurrent key pairs or due to changeover.

   Conforming CAs MUST use the key identifier method, and MUST include
   this extension in all CRLs issued.

   The syntax for this CRL extension is defined in section 4.2.1.1.

5.2.2  Issuer Alternative Name

   The issuer alternative names extension allows additional identities
   to be associated with the issuer of the CRL.  Defined options include
   an rfc822 name (electronic mail address), a DNS name, an IP address,
   and a URI.  Multiple instances of a name and multiple name forms may
   be included.  Whenever such identities are used, the issuer
   alternative name extension MUST be used.

   The issuerAltName extension SHOULD NOT be marked critical.

   The OID and syntax for this CRL extension are defined in section
   4.2.1.8.

5.2.3  CRL Number

   The CRL number is a non-critical CRL extension which conveys a
   monotonically increasing sequence number for each CRL issued by a CA.
   This extension allows users to easily determine when a particular CRL
   supersedes another CRL.  CAs conforming to this profile MUST include
   this extension in all CRLs.

   id-ce-cRLNumber OBJECT IDENTIFIER ::= { id-ce 20 }

   cRLNumber ::= INTEGER (0..MAX)







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5.2.4  Delta CRL Indicator

   The delta CRL indicator is a critical CRL extension that identifies a
   delta-CRL.  The use of delta-CRLs can significantly improve
   processing time for applications which store revocation information
   in a format other than the CRL structure.  This allows changes to be
   added to the local database while ignoring unchanged information that
   is already in the local database.

   When a delta-CRL is issued, the CAs MUST also issue a complete CRL.

   The value of BaseCRLNumber identifies the CRL number of the base CRL
   that was used as the starting point in the generation of this delta-
   CRL.  The delta-CRL contains the changes between the base CRL and the
   current CRL issued along with the delta-CRL.  It is the decision of a
   CA as to whether to provide delta-CRLs.  Again, a delta-CRL MUST NOT
   be issued without a corresponding complete CRL.  The value of
   CRLNumber for both the delta-CRL and the corresponding complete CRL
   MUST be identical.

   A CRL user constructing a locally held CRL from delta-CRLs MUST
   consider the constructed CRL incomplete and unusable if the CRLNumber
   of the received delta-CRL is more than one greater than the CRLnumber
   of the delta-CRL last processed.

   id-ce-deltaCRLIndicator OBJECT IDENTIFIER ::= { id-ce 27 }

   deltaCRLIndicator ::= BaseCRLNumber

   BaseCRLNumber ::= CRLNumber

5.2.5  Issuing Distribution Point

   The issuing distribution point is a critical CRL extension that
   identifies the CRL distribution point for a particular CRL, and it
   indicates whether the CRL covers revocation for end entity
   certificates only, CA  certificates only, or a limitied set of reason
   codes.  Although the extension is critical, conforming
   implementations are not required to support this extension.

   The CRL is signed using the CA's private key.  CRL Distribution
   Points do not have their own key pairs.  If the CRL is stored in the
   X.500 Directory, it is stored in the Directory entry corresponding to
   the CRL distribution point, which may be different than the Directory
   entry of the CA.






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   The reason codes associated with a distribution point shall be
   specified in onlySomeReasons. If onlySomeReasons does not appear, the
   distribution point shall contain revocations for all reason codes.
   CAs may use CRL distribution points to partition the CRL on the basis
   of compromise and routine revocation.  In this case, the revocations
   with reason code keyCompromise (1) and cACompromise (2) appear in one
   distribution point, and the revocations with other reason codes
   appear in another distribution point.

   Where the issuingDistributionPoint extension contains a URL, the
   following semantics MUST be assumed: the object is a pointer to the
   most current CRL issued by this CA.  The URI schemes ftp, http,
   mailto [RFC1738] and ldap [RFC1778] are defined for this purpose.
   The URI MUST be an absolute, not relative, pathname and MUST specify
   the host.

   id-ce-issuingDistributionPoint OBJECT IDENTIFIER ::= { id-ce 28 }

   issuingDistributionPoint ::= SEQUENCE {
        distributionPoint       [0] DistributionPointName OPTIONAL,
        onlyContainsUserCerts   [1] BOOLEAN DEFAULT FALSE,
        onlyContainsCACerts     [2] BOOLEAN DEFAULT FALSE,
        onlySomeReasons         [3] ReasonFlags OPTIONAL,
        indirectCRL             [4] BOOLEAN DEFAULT FALSE }

5.3  CRL Entry Extensions

   The CRL entry extensions already defined by ANSI X9 and ISO/IEC/ITU
   for X.509 v2 CRLs provide methods for associating additional
   attributes with CRL entries [X.509] [X9.55].  The X.509 v2 CRL format
   also allows communities to define private CRL entry extensions to
   carry information unique to those communities.  Each extension in a
   CRL entry may be designated as critical or non-critical.  A CRL
   validation MUST fail if it encounters a critical CRL entry extension
   which it does not know how to process.  However, an unrecognized
   non-critical CRL entry extension may be ignored.  The following
   subsections present recommended extensions used within Internet CRL
   entries and standard locations for information.  Communities may
   elect to use additional CRL entry extensions; however, caution should
   be exercised in adopting any critical extensions in CRL entries which
   might be used in a general context.

   All CRL entry extensions used in this specification are non-critical.
   Support for these extensions is optional for conforming CAs and
   applications.  However, CAs that issue CRLs SHOULD include reason
   codes (see sec. 5.3.1) and invalidity dates (see sec. 5.3.3) whenever
   this information is available.




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5.3.1  Reason Code

   The reasonCode is a non-critical CRL entry extension that identifies
   the reason for the certificate revocation. CAs are strongly
   encouraged to include meaningful reason codes in CRL entries;
   however, the reason code CRL entry extension SHOULD be absent instead
   of using the unspecified (0) reasonCode value.

   id-ce-cRLReason OBJECT IDENTIFIER ::= { id-ce 21 }

   -- reasonCode ::= { CRLReason }

   CRLReason ::= ENUMERATED {
        unspecified             (0),
        keyCompromise           (1),
        cACompromise            (2),
        affiliationChanged      (3),
        superseded              (4),
        cessationOfOperation    (5),
        certificateHold         (6),
        removeFromCRL           (8) }

5.3.2  Hold Instruction Code

   The hold instruction code is a non-critical CRL entry extension that
   provides a registered instruction identifier which indicates the
   action to be taken after encountering a certificate that has been
   placed on hold.

   id-ce-holdInstructionCode OBJECT IDENTIFIER ::= { id-ce 23 }

   holdInstructionCode ::= OBJECT IDENTIFIER

   The following instruction codes have been defined.  Conforming
   applications that process this extension MUST recognize the following
   instruction codes.

   holdInstruction    OBJECT IDENTIFIER ::=
                    { iso(1) member-body(2) us(840) x9-57(10040) 2 }

   id-holdinstruction-none   OBJECT IDENTIFIER ::= {holdInstruction 1}
   id-holdinstruction-callissuer
                             OBJECT IDENTIFIER ::= {holdInstruction 2}
   id-holdinstruction-reject OBJECT IDENTIFIER ::= {holdInstruction 3}

   Conforming applications which encounter an id-holdinstruction-
   callissuer MUST call the certificate issuer or reject the
   certificate.  Conforming applications which encounter an id-



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   holdinstruction-reject MUST reject the certificate. The hold
   instruction id-holdinstruction-none is semantically equivalent to the
   absence of a holdInstructionCode, and its use is strongly deprecated
   for the Internet PKI.

5.3.3  Invalidity Date

   The invalidity date is a non-critical CRL entry extension that
   provides the date on which it is known or suspected that the private
   key was compromised or that the certificate otherwise became invalid.
   This date may be earlier than the revocation date in the CRL entry,
   which is the date at which the CA processed the revocation. When a
   revocation is first posted by a CA in a CRL, the invalidity date may
   precede the date of issue of earlier CRLs, but the revocation date
   SHOULD NOT precede the date of issue of earlier CRLs.  Whenever this
   information is available, CAs are strongly encouraged to share it
   with CRL users.

   The GeneralizedTime values included in this field MUST be expressed
   in Greenwich Mean Time (Zulu), and MUST be specified and interpreted
   as defined in section 4.1.2.5.2.

   id-ce-invalidityDate OBJECT IDENTIFIER ::= { id-ce 24 }

   invalidityDate ::=  GeneralizedTime

5.3.4  Certificate Issuer

   This CRL entry extension identifies the certificate issuer associated
   with an entry in an indirect CRL, i.e. a CRL that has the indirectCRL
   indicator set in its issuing distribution point extension. If this
   extension is not present on the first entry in an indirect CRL, the
   certificate issuer defaults to the CRL issuer. On subsequent entries
   in an indirect CRL, if this extension is not present, the certificate
   issuer for the entry is the same as that for the preceding entry.
   This field is defined as follows:

   id-ce-certificateIssuer   OBJECT IDENTIFIER ::= { id-ce 29 }

   certificateIssuer ::=     GeneralNames

   If used by conforming CAs that issue CRLs, this extension is always
   critical.  If an implementation ignored this extension it could not
   correctly attribute CRL entries to certificates.  This specification
   RECOMMENDS that implementations recognize this extension.






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6  Certification Path Validation

   Certification path validation procedures for the Internet PKI are
   based on section 12.4.3 of [X.509].  Certification path processing
   verifies the binding between the subject distinguished name and/or
   subject alternative name and subject public key.  The binding is
   limited by constraints which are specified in the certificates which
   comprise the path. The basic constraints and policy constraints
   extensions allow the certification path processing logic to automate
   the decision making process.

   This section describes an algorithm for validating certification
   paths.  Conforming implementations of this specification are not
   required to implement this algorithm, but MUST be functionally
   equivalent to the external behavior resulting from this procedure.
   Any algorithm may be used by a particular implementation so long as
   it derives the correct result.

   In section 6.1, the text describes basic path validation. This text
   assumes that all valid paths begin with certificates issued by a
   single "most-trusted CA". The algorithm requires the public key of
   the CA, the CA's name, the validity period of the public key, and any
   constraints upon the set of paths which may be validated using this
   key.

   The "most-trusted CA" is a matter of policy: it could be a root CA in
   a hierarchical PKI; the CA that issued the verifier's own
   certificate(s); or any other CA in a network PKI.  The path
   validation procedure is the same regardless of the choice of "most-
   trusted CA."

   section 6.2 describes extensions to the basic path validation
   algorithm. Two specific cases are discussed: the case where paths may
   begin with one of several trusted CAs; and where compatibility with
   the PEM architecture is required.

6.1 Basic Path Validation

   The text assumes that the trusted public key (and related
   information) is contained in a "self-signed" certificate. This
   simplifies the description of the path processing procedure.  Note
   that the signature on the self-signed certificate does not provide
   any security services.  The trusted public key (and related
   information) may be obtained in other formats; the information is
   trusted because of other procedures used to obtain and protect it.






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   The goal of path validation is to verify the binding between a
   subject distinguished name or subject alternative name and subject
   public key, as represented in the "end entity" certificate, based on
   the public key of the "most-trusted CA".  This requires obtaining a
   sequence of certificates that support that binding.  The procedures
   performed to obtain this sequence is outside the scope of this
   section.

   The following text also assumes that certificates do not use subject
   or unique identifier fields or private critical extensions, as
   recommended within this profile.  However, if these components appear
   in certificates, they MUST be processed.  Finally, policy qualifiers
   are also neglected for the sake of clarity.

   A certification path is a sequence of n certificates where:

      * for all x in {1,(n-1)}, the subject of certificate x is the
      issuer of certificate x+1.
      * certificate x=1 is the the self-signed certificate, and
      * certificate x=n is the end entity certificate.

   This section assumes the following inputs are provided to the path
   processing logic:

      (a)  a certification path of length n;

      (b)  a set of initial policy identifiers (each comprising a
      sequence of policy element identifiers), which identifies one or
      more certificate policies, any one of which would be acceptable
      for the purposes of certification path processing, or the special
      value "any-policy";

      (c)  the current date/time (if not available internally to the
      certification path processing module); and

      (d)  the time, T, for which the validity of the path should be
      determined.  (This may be the current date/time, or some point in
      the past.)

   From the inputs, the procedure intializes five state variables:

      (a)  acceptable policy set:  A set of certificate policy
      identifiers comprising the policy or policies recognized by the
      public key user together with policies deemed equivalent through
      policy mapping. The initial value of the acceptable policy set is
      the special value "any-policy".





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      (b)  constrained subtrees:  A set of root names defining a set of
      subtrees within which all subject names in subsequent certificates
      in the certification path shall fall. The initial value is
      "unbounded".

      (c)  excluded subtrees:  A set of root names defining a set of
      subtrees within which no subject name in subsequent certificates
      in the certification path may fall. The initial value is "empty".

      (d)  explicit policy: an integer which indicates if an explicit
      policy identifier is required. The integer indicates the first
      certificate in the path where this requirement is imposed. Once
      set, this variable may be decreased, but may not be increased.
      (That is, if a certificate in the path requires explicit policy
      identifiers, a later certificate can not remove this requirement.)
      The initial value is n+1.

      (e)  policy mapping: an integer which indicates if policy mapping
      is permitted.  The integer indicates the last certificate on which
      policy mapping may be applied.  Once set, this variable may be
      decreased, but may not be increased. (That is, if a certificate in
      the path specifies policy mapping is not permitted, it can not be
      overriden by a later certificate.) The initial value is n+1.

   The actions performed by the path processing software for each
   certificate i=1 through n are described below.  The self-signed
   certificate is certificate i=1, the end entity certificate is i=n.
   The processing is performed sequentially, so that processing
   certificate i affects the state variables for processing certificate
   (i+1). Note that actions (h) through (m) are not applied to the end
   entity certificate (certificate n).

   The path processing actions to be performed are:

      (a)  Verify the basic certificate information, including:

         (1) the certificate was signed using the subject public key
         from certificate i-1 (in the special case i=1, this step may be
         omitted; if not, use the subject public key from the same
         certificate),

         (2) the certificate validity period includes time T,

         (3) the certificate had not been revoked at time T and is not
         currently on hold status that commenced before time T, (this
         may be determined by obtaining the appropriate CRL or status
         information, or by out-of-band mechanisms), and




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         (4) the subject and issuer names chain correctly (that is, the
         issuer of this certificate was the subject of the previous
         certificate.)

      (b)  Verify that the subject name and subjectAltName extension
      (critical or noncritical) is consistent with the constrained
      subtrees state variables.

      (c)  Verify that the subject name and subjectAltName extension
      (critical or noncritical) is consistent with the excluded subtrees
      state variables.

      (d)  Verify that policy information is consistent with the initial
      policy set:

         (1) if the explicit policy state variable is less than or equal
         to i, a policy identifier in the certificate shall be in the
         initial policy set; and

         (2) if the policy mapping variable is less than or equal to i,
         the policy identifier may not be mapped.

      (e)  Verify that policy information is consistent with the
      acceptable policy set:

         (1) if the certificate policies extension is marked critical,
         the intersection of the policies extension and the acceptable
         policy set shall be non-null;

         (2) the acceptable policy set is assigned the resulting
         intersection as its new value.

      (g) Verify that the intersection of the acceptable policy set and
      the initial policy set is non-null.

      (h)  Recognize and process any other critical extension present in
      the certificate.

      (i) Verify that the certificate is a CA certificate (as specified
      in a basicConstraints extension or as verified out-of-band).

      (j)  If permittedSubtrees is present in the certificate, set the
      constrained subtrees state variable to the intersection of its
      previous value and the value indicated in the extension field.

      (k)  If excludedSubtrees is present in the certificate, set the
      excluded subtrees state variable to the union of its previous
      value and the value indicated in the extension field.



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      (l)  If a policy constraints extension is included in the
      certificate, modify the explicit policy and policy mapping state
      variables as follows:

         (1) If requireExplicitPolicy is present and has value r, the
         explicit policy state variable is set to the minimum of its
         current value and the sum of r and i (the current certificate
         in the sequence).

         (2) If inhibitPolicyMapping is present and has value q, the
         policy mapping state variable is set to the minimum of its
         current value and the sum of q and i (the current certificate
         in the sequence).

      (m) If a key usage extension is marked critical, ensure the
      keyCertSign bit is set.

   If any one of the above checks fail, the procedure terminates,
   returning a failure indication and an appropriate reason.  If none of
   the above checks fail on the end-entity certificate, the procedure
   terminates, returning a success indication together with the set of
   all policy qualifier values encountered in the set of certificates.

6.2 Extending Path Validation

   The path validation algorithm presented in 6.1 is based on several
   simplifying assumptions (e.g., a single trusted CA that starts all
   valid paths). This algorithm may be extended for cases where the
   assumptions do not hold.

   This procedure may be extended for multiple trusted CAs by providing
   a set of self-signed certificates to the validation module.  In this
   case, a valid path could begin with any one of the self-signed
   certificates.  Limitations in the trust paths for any particular key
   may be incorporated into the self-signed certificate's extensions. In
   this way, the self-signed certificates permit the path validation
   module to automatically incorporate local security policy and
   requirements.

   It is also possible to specify an extended version of the above
   certification path processing procedure which results in default
   behavior identical to the rules of PEM [RFC 1422].  In this extended
   version, additional inputs to the procedure are a list of one or more
   Policy Certification Authorities (PCAs) names and an indicator of the
   position in the certification path where the PCA is expected.  At the
   nominated PCA position, the CA name is compared against this list.
   If a recognized PCA name is found, then a constraint of
   SubordinateToCA is implicitly assumed for the remainder of the



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   certification path and processing continues.  If no valid PCA name is
   found, and if the certification path cannot be validated on the basis
   of identified policies, then the certification path is considered
   invalid.

7  Algorithm Support

   This section describes cryptographic algorithms which may be used
   with this profile.  The section describes one-way hash functions and
   digital signature algorithms which may be used to sign certificates
   and CRLs, and identifies OIDs for public keys contained in a
   certificate.

   Conforming CAs and applications are not required to support the
   algorithms or algorithm identifiers described in this section.
   However, conforming CAs and applications that use the algorithms
   identified here MUST support them as specified.

7.1  One-way Hash Functions

   This section identifies one-way hash functions for use in the
   Internet PKI.  One-way hash functions are also called message digest
   algorithms. SHA-1 is the preferred one-way hash function for the
   Internet PKI.  However, PEM uses MD2 for certificates [RFC 1422] [RFC
   1423] and MD5 is used in other legacy applications.  For this reason,
   MD2 and MD5 are included in this profile.

7.1.1  MD2 One-way Hash Function

   MD2 was developed by Ron Rivest for RSA Data Security. RSA Data
   Security has not placed the MD2 algorithm in the public domain.
   Rather, RSA Data Security has granted license to use MD2 for non-
   commercial Internet Privacy-Enhanced Mail.  For this reason, MD2 may
   continue to be used with PEM certificates, but SHA-1 is preferred.
   MD2 produces a 128-bit "hash" of the input.  MD2 is fully described
   in RFC 1319 [RFC 1319].

   At the Selected Areas in Cryptography '95 conference in May 1995,
   Rogier and Chauvaud presented an attack on MD2 that can nearly find
   collisions [RC95].  Collisions occur when one can find two different
   messages that generate the same message digest.  A checksum operation
   in MD2 is the only remaining obstacle to the success of the attack.
   For this reason, the use of MD2 for new applications is discouraged.
   It is still reasonable to use MD2 to verify existing signatures, as
   the ability to find collisions in MD2 does not enable an attacker to
   find new messages having a previously computed hash value.





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7.1.2  MD5 One-way Hash Function

   MD5 was developed by Ron Rivest for RSA Data Security. RSA Data
   Security has placed the MD5 algorithm in the public domain.  MD5
   produces a 128-bit "hash" of the input.  MD5 is fully described in
   RFC 1321 [RFC 1321].

   Den Boer and Bosselaers [DB94] have found pseudo-collisions for MD5,
   but there are no other known cryptanalytic results.  The use of MD5
   for new applications is discouraged.  It is still reasonable to use
   MD5 to verify existing signatures.

7.1.3  SHA-1 One-way Hash Function

   SHA-1 was developed by the U.S. Government.  SHA-1 produces a 160-bit
   "hash" of the input. SHA-1 is fully described in FIPS 180-1 [FIPS
   180-1].

   SHA-1 is the one-way hash function of choice for use with both the
   RSA and DSA signature algorithms (see sec. 7.2).

7.2  Signature Algorithms

   Certificates and CRLs described by this standard may be signed with
   any public key signature algorithm.  The certificate or CRL indicates
   the algorithm through an algorithm identifier which appears in the
   signatureAlgorithm field in a Certificate or CertificateList.  This
   algorithm identifier is an OID and has optionally associated
   parameters.  This section identifies algorithm identifiers and
   parameters that shall be used in the signatureAlgorithm field in a
   Certificate or CertificateList.

   RSA and DSA are the most popular signature algorithms used in the
   Internet.  Signature algorithms are always used in conjunction with a
   one-way hash function identified in section 7.1.

   The signature algorithm and one-way hash function used to sign a
   certificate or CRL is indicated by use of an algorithm identifier.
   An algorithm identifier is an OID, and may include associated
   parameters.  This section identifies OIDS for RSA and DSA.  The
   contents of the parameters component for each algorithm vary; details
   are provided for each algorithm.

   The data to be signed (e.g., the one-way hash function output value)
   is formatted for the signature algorithm to be used.  Then, a private
   key operation (e.g., RSA encryption) is performed to generate the





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   signature value.  This signature value is then ASN.1 encoded as a BIT
   STRING and included in the Certificate or CertificateList in the
   signature field.

7.2.1  RSA Signature Algorithm

   A patent statement regarding the RSA algorithm can be found at the
   end of this profile.

   The RSA algorithm is named for its inventors: Rivest, Shamir, and
   Adleman.  This profile includes three signature algorithms based on
   the RSA asymmetric encryption algorithm. The signature algorithms
   combine RSA with either the MD2, MD5, or the SHA-1 one-way hash
   functions.

   The signature algorithm with MD2 and the RSA encryption algorithm is
   defined in PKCS #1 [RFC 2313].  As defined in RFC 2313, the ASN.1 OID
   used to identify this signature algorithm is:

        md2WithRSAEncryption OBJECT IDENTIFIER  ::=  {
            iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)
            pkcs-1(1) 2  }

   The signature algorithm with MD5 and the RSA encryption algorithm is
   defined in PKCS #1 [RFC 2313].  As defined in RFC 2313, the ASN.1 OID
   used to identify this signature algorithm is:

        md5WithRSAEncryption OBJECT IDENTIFIER  ::=  {
            iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)
            pkcs-1(1) 4  }

   The signature algorithm with SHA-1 and the RSA encryption algorithm
   is implemented using the padding and encoding conventions described
   in PKCS #1 [RFC 2313]. The message digest is computed using the SHA-1
   hash algorithm.  The ASN.1 object identifier used to identify this
   signature algorithm is:

        sha-1WithRSAEncryption OBJECT IDENTIFIER  ::=  {
            iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)
            pkcs-1(1) 5  }

   When any of these three OIDs appears within the ASN.1 type
   AlgorithmIdentifier, the parameters component of that type shall be
   the ASN.1 type NULL.

   The RSA signature generation process and the encoding of the result
   is described in detail in RFC 2313.




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7.2.2  DSA Signature Algorithm

   A patent statement regarding the DSA can be found at the end of this
   profile.

   The Digital Signature Algorithm (DSA) is also called the Digital
   Signature Standard (DSS).  DSA was developed by the U.S. Government,
   and DSA is used in conjunction with the the SHA-1 one-way hash
   function.  DSA is fully described in FIPS 186 [FIPS 186].  The ASN.1
   OIDs used to identify this signature algorithm are:

           id-dsa-with-sha1 ID  ::=  {
                   iso(1) member-body(2) us(840) x9-57 (10040)
                   x9cm(4) 3 }

   Where the id-dsa-with-sha1 algorithm identifier appears as the
   algorithm field in an AlgorithmIdentifier, the encoding shall omit
   the parameters field.  That is, the AlgorithmIdentifier shall be a
   SEQUENCE of one component - the OBJECT IDENTIFIER id-dsa-with-sha1.

   The DSA parameters in the subjectPublicKeyInfo field of the
   certificate of the issuer shall apply to the verification of the
   signature.

   When signing, the DSA algorithm generates two values.  These values
   are commonly referred to as r and s.  To easily transfer these two
   values as one signature, they shall be ASN.1 encoded using the
   following ASN.1 structure:

           Dss-Sig-Value  ::=  SEQUENCE  {
                   r       INTEGER,
                   s       INTEGER  }

7.3  Subject Public Key Algorithms

   Certificates described by this profile may convey a public key for
   any public key algorithm. The certificate indicates the algorithm
   through an algorithm identifier.  This algorithm identifier is an OID
   and optionally associated parameters.

   This section identifies preferred OIDs and parameters for the RSA,
   DSA, and Diffie-Hellman algorithms.  Conforming CAs shall use the
   identified OIDs when issuing certificates containing public keys for
   these algorithms. Conforming applications supporting any of these
   algorithms shall, at a minimum, recognize the OID identified in this
   section.





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7.3.1  RSA Keys

   The OID rsaEncryption identifies RSA public keys.

        pkcs-1 OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840)
                       rsadsi(113549) pkcs(1) 1 }

        rsaEncryption OBJECT IDENTIFIER ::=  { pkcs-1 1}

   The rsaEncryption OID is intended to be used in the algorithm field
   of a value of type AlgorithmIdentifier. The parameters field shall
   have ASN.1 type NULL for this algorithm identifier.

   The RSA public key shall be encoded using the ASN.1 type
   RSAPublicKey:

      RSAPublicKey ::= SEQUENCE {
         modulus            INTEGER, -- n
         publicExponent     INTEGER  -- e -- }

   where modulus is the modulus n, and publicExponent is the public
   exponent e.  The DER encoded RSAPublicKey is the value of the BIT
   STRING subjectPublicKey.

   This OID is used in public key certificates for both RSA signature
   keys and RSA encryption keys. The intended application for the key
   may be indicated in the key usage field (see sec. 4.2.1.3).  The use
   of a single key for both signature and encryption purposes is not
   recommended, but is not forbidden.

   If the keyUsage extension is present in an end entity certificate
   which conveys an RSA public key, any combination of the following
   values may be present:  digitalSignature; nonRepudiation;
   keyEncipherment; and dataEncipherment.  If the keyUsage extension is
   present in a CA certificate which conveys an RSA public key, any
   combination of the following values may be present:
   digitalSignature; nonRepudiation; keyEncipherment; dataEncipherment;
   keyCertSign; and cRLSign.  However, this specification RECOMMENDS
   that if keyCertSign or cRLSign is present, both keyEncipherment and
   dataEncipherment should not be present.

7.3.2  Diffie-Hellman Key Exchange Key

   The Diffie-Hellman OID supported by this profile is defined by ANSI
   X9.42 [X9.42].

        dhpublicnumber OBJECT IDENTIFIER ::= { iso(1) member-body(2)
                  us(840) ansi-x942(10046) number-type(2) 1 }



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   The dhpublicnumber OID is intended to be used in the algorithm field
   of a value of type AlgorithmIdentifier. The parameters field of that
   type, which has the algorithm-specific syntax ANY DEFINED BY
   algorithm, have the ASN.1 type DomainParameters for this algorithm.

        DomainParameters ::= SEQUENCE {
              p       INTEGER, -- odd prime, p=jq +1
              g       INTEGER, -- generator, g
              q       INTEGER, -- factor of p-1
              j       INTEGER OPTIONAL, -- subgroup factor
              validationParms  ValidationParms OPTIONAL }

        ValidationParms ::= SEQUENCE {
              seed             BIT STRING,
              pgenCounter      INTEGER }

   The fields of type DomainParameters have the following meanings:

      p identifies the prime p defining the Galois field;

      g specifies the generator of the multiplicative subgroup of order
      g;

      q specifies the prime factor of p-1;

      j optionally specifies the value that satisfies the equation
      p=jq+1 to support the optional verification of group parameters;

      seed optionally specifies the bit string parameter used as the
      seed for the system parameter generation process; and

      pgenCounter optionally specifies the integer value output as part
      of the of the system parameter prime generation process.

   If either of the parameter generation components (pgencounter or
   seed) is provided, the other shall be present as well.

   The Diffie-Hellman public key shall be ASN.1 encoded as an INTEGER;
   this encoding shall be used as the contents (i.e., the value) of the
   subjectPublicKey component (a BIT STRING) of the subjectPublicKeyInfo
   data element.

      DHPublicKey ::= INTEGER -- public key, y = g^x mod p








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   If the keyUsage extension is present in a certificate which conveys a
   DH public key, the following values may be present:  keyAgreement;
   encipherOnly; and decipherOnly.  At most one of encipherOnly and
   decipherOnly shall be asserted in keyUsage extension.

7.3.3  DSA Signature Keys

   The Digital Signature Algorithm (DSA) is also known as the Digital
   Signature Standard (DSS). The DSA OID supported by this profile is

        id-dsa ID ::= { iso(1) member-body(2) us(840) x9-57(10040)
                  x9cm(4) 1 }

   The id-dsa algorithm syntax includes optional parameters.  These
   parameters are commonly referred to as p, q, and g.  When omitted,
   the parameters component shall be omitted entirely. That is, the
   AlgorithmIdentifier shall be a SEQUENCE of one component - the OBJECT
   IDENTIFIER id-dsa.

   If the DSA algorithm parameters are present in the
   subjectPublicKeyInfo AlgorithmIdentifier, the parameters are included
   using the following ASN.1 structure:

        Dss-Parms  ::=  SEQUENCE  {
            p             INTEGER,
            q             INTEGER,
            g             INTEGER  }


   If the DSA algorithm parameters are absent from the
   subjectPublicKeyInfo AlgorithmIdentifier and the CA signed the
   subject certificate using DSA, then the certificate issuer's DSA
   parameters apply to the subject's DSA key.  If the DSA algorithm
   parameters are absent from the subjectPublicKeyInfo
   AlgorithmIdentifier and the CA signed the subject certificate using a
   signature algorithm other than DSA, then the subject's DSA parameters
   are distributed by other means.  If the subjectPublicKeyInfo
   AlgorithmIdentifier field omits the parameters component and the CA
   signed the subject with a signature algorithm other than DSA, then
   clients shall reject the certificate.

   When signing, DSA algorithm generates two values.  These values are
   commonly referred to as r and s.  To easily transfer these two values
   as one signature, they are ASN.1 encoded using the following ASN.1
   structure:






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        Dss-Sig-Value  ::=  SEQUENCE  {
            r             INTEGER,
            s             INTEGER  }

   The encoded signature is conveyed as the value of the BIT STRING
   signature in a Certificate or CertificateList.

   The DSA public key shall be ASN.1 DER encoded as an INTEGER; this
   encoding shall be used as the contents (i.e., the value) of the
   subjectPublicKey component (a BIT STRING) of the SubjectPublicKeyInfo
   data element.

        DSAPublicKey ::= INTEGER -- public key, Y

   If the keyUsage extension is present in an end entity certificate
   which conveys a DSA public key, any combination of the following
   values may be present:  digitalSignature; and nonRepudiation.

   If the keyUsage extension is present in an CA certificate which
   conveys a DSA public key, any combination of the following values may
   be present:  digitalSignature; nonRepudiation; keyCertSign; and
   cRLSign.

8 References

   [FIPS 180-1]  Federal Information Processing Standards Publication
                 (FIPS PUB) 180-1, Secure Hash Standard, 17 April 1995.
                 [Supersedes FIPS PUB 180 dated 11 May 1993.]

   [FIPS 186]    Federal Information Processing Standards Publication
                 (FIPS PUB) 186, Digital Signature Standard, 18 May
                 1994.

   [RC95]        Rogier, N. and Chauvaud, P., "The compression function
                 of MD2 is not collision free," Presented at Selected
                 Areas in Cryptography '95, May 1995.

   [RFC 791]     Postel, J., "Internet Protocol", STD 5, RFC 791,
                 September 1981.

   [RFC 822]     Crocker, D., "Standard for the format of ARPA Internet
                 text messages", STD 11, RFC 822, August 1982.

   [RFC 1034]    Mockapetris, P., "Domain names - concepts and
                 facilities", STD 13, RFC 1034, November 1987.

   [RFC 1319]    Kaliski, B., "The MD2 Message-Digest Algorithm," RFC
                 1319, April 1992.



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   [RFC 1321]    Rivest, R., "The MD5 Message-Digest Algorithm," RFC
                 1321, April 1992.

   [RFC 1422]    Kent, S.,  "Privacy Enhancement for Internet Electronic
                 Mail: Part II: Certificate-Based Key Management," RFC
                 1422, February 1993.

   [RFC 1423]    Balenson, D., "Privacy Enhancement for Internet
                 Electronic Mail: Part III: Algorithms, Modes, and
                 Identifiers," RFC 1423, February 1993.

   [RFC 1519]    Fuller, V., Li, T., Yu, J. and K. Varadhan. "Classless
                 Inter-Domain Routing (CIDR): an Address Assignment and
                 Aggregation Strategy", RFC 1519, September 1993.

   [RFC 1738]    Berners-Lee, T., Masinter L., and M. McCahill.
                 "Uniform Resource Locators (URL)", RFC 1738, December
                 1994.

   [RFC 1778]    Howes, T., Kille S., Yeong, W. and C. Robbins. "The
                 String Representation of Standard Attribute Syntaxes,"
                 RFC 1778, March 1995.

   [RFC 1883]    Deering, S. and R. Hinden. "Internet Protocol, Version
                 6 (IPv6) Specification", RFC 1883, December 1995.

   [RFC 2119]    Bradner, S., "Key words for use in RFCs to Indicate
                 Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC 2247]    Kille, S., Wahl, M., Grimstad, A., Huber, R. and S.
                 Sataluri. "Using Domains in LDAP/X.500 Distinguished
                 Names", RFC 2247, January 1998.

   [RFC 2277]    Alvestrand, H., "IETF Policy on Character Sets and
                 Languages", RFC 2277, January 1998.

   [RFC 2279]    Yergeau, F., "UTF-8, a transformation format of ISO
                 10646", RFC 2279, January 1998.

   [RFC 2313]    Kaliski, B., "PKCS #1: RSA Encryption Version 1.5", RFC
                 2313, March 1998.

   [SDN.701]     SDN.701, "Message Security Protocol 4.0", Revision A
                 1997-02-06.

   [X.208]       CCITT Recommendation X.208: Specification of Abstract
                 Syntax Notation One (ASN.1), 1988.




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   [X.501]       ITU-T Recommendation X.501: Information Technology -
                 Open Systems Interconnection - The Directory: Models,
                 1993.

   [X.509]       ITU-T Recommendation X.509 (1997 E): Information
                 Technology - Open Systems Interconnection - The
                 Directory: Authentication Framework, June 1997.

   [X.520]       ITU-T Recommendation X.520: Information Technology -
                 Open Systems Interconnection - The Directory: Selected
                 Attribute Types, 1993.

   [X9.42]       ANSI X9.42-199x, Public Key Cryptography for The
                 Financial Services Industry: Agreement of Symmetric
                 Algorithm Keys Using Diffie-Hellman (Working Draft),
                 December 1997.

   [X9.55]       ANSI X9.55-1995, Public Key Cryptography For The
                 Financial Services Industry: Extensions To Public Key
                 Certificates And Certificate Revocation Lists, 8
                 December, 1995.

   [X9.57]        ANSI X9.57-199x, Public Key Cryptography For The
                 Financial Services Industry: Certificate Management
                 (Working Draft), 21 June, 1996.

9  Intellectual Property Rights

   The IETF has been notified of intellectual property rights claimed in
   regard to some or all of the specification contained in this
   document.  For more information consult the online list of claimed
   rights.

   The IETF takes no position regarding the validity or scope of any
   intellectual property or other rights that might be claimed to
   pertain to the implementation or use of the technology described in
   this document or the extent to which any license under such rights
   might or might not be available; neither does it represent that it
   has made any effort to identify any such rights. Information on the
   IETF's procedures with respect to rights in standards-track and
   standards-related documentation can be found in BCP-11. Copies of
   claims of rights made available for publication and any assurances of
   licenses to be made available, or the result of an attempt made to








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   obtain a general license or permission for the use of such
   proprietary rights by implementors or users of this specification can
   be obtained from the IETF Secretariat.

10  Security Considerations

   The majority of this specification is devoted to the format and
   content of certificates and CRLs.  Since certificates and CRLs are
   digitally signed, no additional integrity service is necessary.
   Neither certificates nor CRLs need be kept secret, and unrestricted
   and anonymous access to certificates and CRLs has no security
   implications.

   However, security factors outside the scope of this specification
   will affect the assurance provided to certificate users.  This
   section highlights critical issues that should be considered by
   implementors, administrators, and users.

   The procedures performed by CAs and RAs to validate the binding of
   the subject's identity of their public key greatly affect the
   assurance that should be placed in the certificate.  Relying parties
   may wish to review the CA's certificate practice statement.  This may
   be particularly important when issuing certificates to other CAs.

   The use of a single key pair for both signature and other purposes is
   strongly discouraged. Use of separate key pairs for signature and key
   management provides several benefits to the users. The ramifications
   associated with loss or disclosure of a signature key are different
   from loss or disclosure of a key management key. Using separate key
   pairs permits a balanced and flexible response.  Similarly, different
   validity periods or key lengths for each key pair may be appropriate
   in some application environments. Unfortunately, some legacy
   applications (e.g., SSL) use a single key pair for signature and key
   management.

   The protection afforded private keys is a critical factor in
   maintaining security.  On a small scale, failure of users to protect
   their private keys will permit an attacker to masquerade as them, or
   decrypt their personal information. On a larger scale, compromise of
   a CA's private signing key may have a catastrophic effect.  If an
   attacker obtains the private key unnoticed, the attacker may issue
   bogus certificates and CRLs.  Existence of bogus certificates and
   CRLs will undermine confidence in the system. If the compromise is
   detected, all certificates issued to the CA shall be revoked,
   preventing services between its users and users of other CAs.
   Rebuilding after such a compromise will be problematic, so CAs are
   advised to implement a combination of strong technical measures
   (e.g., tamper-resistant cryptographic modules) and appropriate



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   management procedures (e.g., separation of duties) to avoid such an
   incident.

   Loss of a CA's private signing key may also be problematic.  The CA
   would not be able to produce CRLs or perform normal key rollover.
   CAs are advised to maintain secure backup for signing keys.  The
   security of the key backup procedures is a critical factor in
   avoiding key compromise.

   The availability and freshness of revocation information will affect
   the degree of assurance that should be placed in a certificate.
   While certificates expire naturally, events may occur during its
   natural lifetime which negate the binding between the subject and
   public key.  If revocation information is untimely or unavailable,
   the assurance associated with the binding is clearly reduced.
   Similarly, implementations of the Path Validation mechanism described
   in section 6 that omit revocation checking provide less assurance
   than those that support it.

   The path validation algorithm depends on the certain knowledge of the
   public keys (and other information) about one or more trusted CAs.
   The decision to trust a CA is an important decision as it ultimately
   determines the trust afforded a certificate. The authenticated
   distribution of trusted CA public keys (usually in the form of a
   "self-signed" certificate) is a security critical out of band process
   that is beyond the scope of this specification.

   In addition, where a key compromise or CA failure occurs for a
   trusted CA, the user will need to modify the information provided to
   the path validation routine.  Selection of too many trusted CAs will
   make the trusted CA information difficult to maintain.  On the other
   hand, selection of only one trusted CA may limit users to a closed
   community of users until a global PKI emerges.

   The quality of implementations that process certificates may also
   affect the degree of assurance provided.  The path validation
   algorithm described in section 6 relies upon the integrity of the
   trusted CA information, and especially the integrity of the public
   keys associated with the trusted CAs.  By substituting public keys
   for which an attacker has the private key, an attacker could trick
   the user into accepting false certificates.

   The binding between a key and certificate subject cannot be stronger
   than the cryptographic module implementation and algorithms used to
   generate the signature.  Short key lengths or weak hash algorithms
   will limit the utility of a certificate.  CAs are encouraged to note
   advances in cryptology so they can employ strong cryptographic
   techniques.  In addition, CAs should decline to issue certificates to



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   CAs or end entities that generate weak signatures.

   Inconsistent application of name comparison rules may result in
   acceptance of invalid X.509 certification paths, or rejection of
   valid ones.  The X.500 series of specifications defines rules for
   comparing distinguished names require comparison of strings without
   regard to case, character set, multi-character white space substring,
   or leading and trailing white space.  This specification relaxes
   these requirements, requiring support for binary comparison at a
   minimum.

   CAs shall encode the distinguished name in the subject field of a CA
   certificate identically to the distinguished name in the issuer field
   in certificates issued by the latter CA.  If CAs use different
   encodings, implementations of this specification may fail to
   recognize name chains for paths that include this certificate.  As a
   consequence, valid paths could be rejected.

   In addition, name constraints for distinguished names shall be stated
   identically to the encoding used in the subject field or
   subjectAltName extension.  If not, (1) name constraints stated as
   excludedSubTrees will not match and invalid paths will be accepted
   and (2) name constraints expressed as permittedSubtrees will not
   match and valid paths will be rejected.  To avoid acceptance of
   invalid paths, CAs should state name constraints for distinguished
   names as permittedSubtrees where ever possible.

























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Appendix A. Psuedo-ASN.1 Structures and OIDs

   This section describes data objects used by conforming PKI components
   in an "ASN.1-like" syntax.  This syntax is a hybrid of the 1988 and
   1993 ASN.1 syntaxes.  The 1988 ASN.1 syntax is augmented with 1993
   UNIVERSAL Types UniversalString, BMPString and UTF8String.

   The ASN.1 syntax does not permit the inclusion of type statements in
   the ASN.1 module, and the 1993 ASN.1 standard does not permit use of
   the new UNIVERSAL types in modules using the 1988 syntax.  As a
   result, this module does not conform to either version of the ASN.1
   standard.

   This appendix may be converted into 1988 ASN.1 by replacing the
   defintions for the UNIVERSAL Types with the 1988 catch-all "ANY".

A.1 Explicitly Tagged Module, 1988 Syntax

PKIX1Explicit88 {iso(1) identified-organization(3) dod(6) internet(1)
  security(5) mechanisms(5) pkix(7) id-mod(0) id-pkix1-explicit-88(1)}


DEFINITIONS EXPLICIT TAGS ::=

BEGIN

-- EXPORTS ALL --

-- IMPORTS NONE --

-- UNIVERSAL Types defined in '93 and '98 ASN.1
-- but required by this specification

UniversalString ::= [UNIVERSAL 28] IMPLICIT OCTET STRING
        -- UniversalString is defined in ASN.1:1993

BMPString ::= [UNIVERSAL 30] IMPLICIT OCTET STRING
      -- BMPString is the subtype of UniversalString and models
       -- the Basic Multilingual Plane of ISO/IEC/ITU 10646-1

UTF8String ::= [UNIVERSAL 12] IMPLICIT OCTET STRING
        -- The content of this type conforms to RFC 2279.

--
-- PKIX specific OIDs

id-pkix  OBJECT IDENTIFIER  ::=
         { iso(1) identified-organization(3) dod(6) internet(1)



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                    security(5) mechanisms(5) pkix(7) }
-- PKIX arcs

id-pe OBJECT IDENTIFIER  ::=  { id-pkix 1 }
        -- arc for private certificate extensions
id-qt OBJECT IDENTIFIER ::= { id-pkix 2 }
        -- arc for policy qualifier types
id-kp OBJECT IDENTIFIER ::= { id-pkix 3 }
        -- arc for extended key purpose OIDS
id-ad OBJECT IDENTIFIER ::= { id-pkix 48 }
        -- arc for access descriptors

-- policyQualifierIds for Internet policy qualifiers

id-qt-cps      OBJECT IDENTIFIER ::=  { id-qt 1 }
        -- OID for CPS qualifier
id-qt-unotice  OBJECT IDENTIFIER ::=  { id-qt 2 }
        -- OID for user notice qualifier

-- access descriptor definitions

id-ad-ocsp      OBJECT IDENTIFIER ::= { id-ad 1 }
id-ad-caIssuers OBJECT IDENTIFIER ::= { id-ad 2 }

-- attribute data types --

Attribute       ::=     SEQUENCE {
        type            AttributeType,
        values  SET OF AttributeValue
                -- at least one value is required -- }

AttributeType           ::=   OBJECT IDENTIFIER

AttributeValue          ::=   ANY

AttributeTypeAndValue           ::=     SEQUENCE {
        type    AttributeType,
        value   AttributeValue }

-- suggested naming attributes: Definition of the following
--  information object set may be augmented to meet local
--  requirements.  Note that deleting members of the set may
--  prevent interoperability with conforming implementations.
--  presented in pairs: the AttributeType followed by the
--  type definition for the corresponding AttributeValue

--Arc for standard naming attributes
id-at           OBJECT IDENTIFIER ::= {joint-iso-ccitt(2) ds(5) 4}



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-- Attributes of type NameDirectoryString
id-at-name              AttributeType   ::=     {id-at 41}
id-at-surname           AttributeType   ::=     {id-at 4}
id-at-givenName         AttributeType   ::=     {id-at 42}
id-at-initials          AttributeType   ::=     {id-at 43}
id-at-generationQualifier       AttributeType   ::=     {id-at 44}

X520name        ::= CHOICE {
      teletexString         TeletexString (SIZE (1..ub-name)),
      printableString       PrintableString (SIZE (1..ub-name)),
      universalString       UniversalString (SIZE (1..ub-name)),
      utf8String            UTF8String (SIZE (1..ub-name)),
      bmpString             BMPString (SIZE(1..ub-name))   }

--

id-at-commonName        AttributeType   ::=     {id-at 3}

X520CommonName  ::=      CHOICE {
      teletexString         TeletexString (SIZE (1..ub-common-name)),
      printableString       PrintableString (SIZE (1..ub-common-name)),
      universalString       UniversalString (SIZE (1..ub-common-name)),
      utf8String            UTF8String (SIZE (1..ub-common-name)),
      bmpString             BMPString (SIZE(1..ub-common-name))   }

--

id-at-localityName      AttributeType   ::=     {id-at 7}

X520LocalityName ::= CHOICE {
      teletexString       TeletexString (SIZE (1..ub-locality-name)),
      printableString     PrintableString (SIZE (1..ub-locality-name)),
      universalString     UniversalString (SIZE (1..ub-locality-name)),
      utf8String          UTF8String (SIZE (1..ub-locality-name)),
      bmpString           BMPString (SIZE(1..ub-locality-name))   }

--

id-at-stateOrProvinceName       AttributeType   ::=     {id-at 8}

X520StateOrProvinceName         ::= CHOICE {
      teletexString       TeletexString (SIZE (1..ub-state-name)),
      printableString     PrintableString (SIZE (1..ub-state-name)),
      universalString     UniversalString (SIZE (1..ub-state-name)),
      utf8String          UTF8String (SIZE (1..ub-state-name)),
      bmpString           BMPString (SIZE(1..ub-state-name))   }

--



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id-at-organizationName          AttributeType   ::=     {id-at 10}

X520OrganizationName ::= CHOICE {
  teletexString     TeletexString (SIZE (1..ub-organization-name)),
  printableString   PrintableString (SIZE (1..ub-organization-name)),
  universalString   UniversalString (SIZE (1..ub-organization-name)),
  utf8String        UTF8String (SIZE (1..ub-organization-name)),
  bmpString         BMPString (SIZE(1..ub-organization-name))   }

--

id-at-organizationalUnitName    AttributeType   ::=     {id-at 11}

X520OrganizationalUnitName ::= CHOICE {
 teletexString    TeletexString (SIZE (1..ub-organizational-unit-name)),
 printableString        PrintableString
                      (SIZE (1..ub-organizational-unit-name)),
 universalString        UniversalString
                      (SIZE (1..ub-organizational-unit-name)),
 utf8String       UTF8String (SIZE (1..ub-organizational-unit-name)),
 bmpString        BMPString (SIZE(1..ub-organizational-unit-name))   }

--

id-at-title     AttributeType   ::=     {id-at 12}

X520Title ::=   CHOICE {
      teletexString         TeletexString (SIZE (1..ub-title)),
      printableString       PrintableString (SIZE (1..ub-title)),
      universalString       UniversalString (SIZE (1..ub-title)),
      utf8String            UTF8String (SIZE (1..ub-title)),
      bmpString             BMPString (SIZE(1..ub-title))   }

--

id-at-dnQualifier       AttributeType   ::=     {id-at 46}
X520dnQualifier ::=     PrintableString

id-at-countryName       AttributeType   ::=     {id-at 6}
X520countryName ::=     PrintableString (SIZE (2)) -- IS 3166 codes


 -- Legacy attributes

pkcs-9 OBJECT IDENTIFIER ::=
       { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) 9 }

emailAddress AttributeType      ::= { pkcs-9 1 }



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Pkcs9email ::= IA5String (SIZE (1..ub-emailaddress-length))

-- naming data types --

Name            ::=   CHOICE { -- only one possibility for now --
                                 rdnSequence  RDNSequence }

RDNSequence     ::=   SEQUENCE OF RelativeDistinguishedName

DistinguishedName       ::=   RDNSequence

RelativeDistinguishedName  ::=
                    SET SIZE (1 .. MAX) OF AttributeTypeAndValue

-- Directory string type --

DirectoryString ::= CHOICE {
      teletexString             TeletexString (SIZE (1..MAX)),
      printableString           PrintableString (SIZE (1..MAX)),
      universalString           UniversalString (SIZE (1..MAX)),
      utf8String              UTF8String (SIZE (1..MAX)),
      bmpString               BMPString (SIZE(1..MAX))   }

-- certificate and CRL specific structures begin here

Certificate  ::=  SEQUENCE  {
     tbsCertificate       TBSCertificate,
     signatureAlgorithm   AlgorithmIdentifier,
     signature            BIT STRING  }

TBSCertificate  ::=  SEQUENCE  {
     version         [0]  Version DEFAULT v1,
     serialNumber         CertificateSerialNumber,
     signature            AlgorithmIdentifier,
     issuer               Name,
     validity             Validity,
     subject              Name,
     subjectPublicKeyInfo SubjectPublicKeyInfo,
     issuerUniqueID  [1]  IMPLICIT UniqueIdentifier OPTIONAL,
                          -- If present, version shall be v2 or v3
     subjectUniqueID [2]  IMPLICIT UniqueIdentifier OPTIONAL,
                          -- If present, version shall be v2 or v3
     extensions      [3]  Extensions OPTIONAL
                          -- If present, version shall be v3 --  }

Version  ::=  INTEGER  {  v1(0), v2(1), v3(2)  }

CertificateSerialNumber  ::=  INTEGER



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Validity ::= SEQUENCE {
     notBefore      Time,
     notAfter       Time }

Time ::= CHOICE {
     utcTime        UTCTime,
     generalTime    GeneralizedTime }

UniqueIdentifier  ::=  BIT STRING

SubjectPublicKeyInfo  ::=  SEQUENCE  {
     algorithm            AlgorithmIdentifier,
     subjectPublicKey     BIT STRING  }

Extensions  ::=  SEQUENCE SIZE (1..MAX) OF Extension

Extension  ::=  SEQUENCE  {
     extnID      OBJECT IDENTIFIER,
     critical    BOOLEAN DEFAULT FALSE,
     extnValue   OCTET STRING  }

-- CRL structures

CertificateList  ::=  SEQUENCE  {
     tbsCertList          TBSCertList,
     signatureAlgorithm   AlgorithmIdentifier,
     signature            BIT STRING  }

TBSCertList  ::=  SEQUENCE  {
     version                 Version OPTIONAL,
                                  -- if present, shall be v2
     signature               AlgorithmIdentifier,
     issuer                  Name,
     thisUpdate              Time,
     nextUpdate              Time OPTIONAL,
     revokedCertificates     SEQUENCE OF SEQUENCE  {
          userCertificate         CertificateSerialNumber,
          revocationDate          Time,
          crlEntryExtensions      Extensions OPTIONAL
                                         -- if present, shall be v2
                               }  OPTIONAL,
     crlExtensions           [0] Extensions OPTIONAL
                                         -- if present, shall be v2 -- }

-- Version, Time, CertificateSerialNumber, and Extensions were
-- defined earlier for use in the certificate structure

AlgorithmIdentifier  ::=  SEQUENCE  {



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     algorithm               OBJECT IDENTIFIER,
     parameters              ANY DEFINED BY algorithm OPTIONAL  }
                                -- contains a value of the type
                                -- registered for use with the
                                -- algorithm object identifier value

-- Algorithm OIDs and parameter structures

pkcs-1 OBJECT IDENTIFIER ::= {
     iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) 1 }

rsaEncryption OBJECT IDENTIFIER ::=  { pkcs-1 1 }

md2WithRSAEncryption OBJECT IDENTIFIER  ::=  { pkcs-1 2 }

md5WithRSAEncryption OBJECT IDENTIFIER  ::=  { pkcs-1 4 }

sha1WithRSAEncryption OBJECT IDENTIFIER  ::=  { pkcs-1 5 }

id-dsa-with-sha1 OBJECT IDENTIFIER ::=  {
     iso(1) member-body(2) us(840) x9-57 (10040) x9algorithm(4) 3 }

Dss-Sig-Value  ::=  SEQUENCE  {
     r       INTEGER,
     s       INTEGER  }

dhpublicnumber OBJECT IDENTIFIER ::= {
     iso(1) member-body(2) us(840) ansi-x942(10046) number-type(2) 1 }

DomainParameters ::= SEQUENCE {
     p       INTEGER, -- odd prime, p=jq +1
     g       INTEGER, -- generator, g
     q       INTEGER, -- factor of p-1
     j       INTEGER OPTIONAL, -- subgroup factor, j>= 2
     validationParms  ValidationParms OPTIONAL }

ValidationParms ::= SEQUENCE {
     seed             BIT STRING,
     pgenCounter      INTEGER }

id-dsa OBJECT IDENTIFIER ::= {
     iso(1) member-body(2) us(840) x9-57(10040) x9algorithm(4) 1 }

Dss-Parms  ::=  SEQUENCE  {
     p             INTEGER,
     q             INTEGER,
     g             INTEGER  }




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-- x400 address syntax starts here
--      OR Names

ORAddress ::= SEQUENCE {
   built-in-standard-attributes BuiltInStandardAttributes,
   built-in-domain-defined-attributes
                        BuiltInDomainDefinedAttributes OPTIONAL,
   -- see also teletex-domain-defined-attributes
   extension-attributes ExtensionAttributes OPTIONAL }
--      The OR-address is semantically absent from the OR-name if the
--      built-in-standard-attribute sequence is empty and the
--      built-in-domain-defined-attributes and extension-attributes are
--      both omitted.

--      Built-in Standard Attributes

BuiltInStandardAttributes ::= SEQUENCE {
   country-name CountryName OPTIONAL,
   administration-domain-name AdministrationDomainName OPTIONAL,
   network-address      [0] NetworkAddress OPTIONAL,
   -- see also extended-network-address
   terminal-identifier  [1] TerminalIdentifier OPTIONAL,
   private-domain-name  [2] PrivateDomainName OPTIONAL,
   organization-name    [3] OrganizationName OPTIONAL,
   -- see also teletex-organization-name
   numeric-user-identifier      [4] NumericUserIdentifier OPTIONAL,
   personal-name        [5] PersonalName OPTIONAL,
   -- see also teletex-personal-name
   organizational-unit-names    [6] OrganizationalUnitNames OPTIONAL
   -- see also teletex-organizational-unit-names -- }

CountryName ::= [APPLICATION 1] CHOICE {
   x121-dcc-code NumericString
                (SIZE (ub-country-name-numeric-length)),
   iso-3166-alpha2-code PrintableString
                (SIZE (ub-country-name-alpha-length)) }

AdministrationDomainName ::= [APPLICATION 2] CHOICE {
   numeric NumericString (SIZE (0..ub-domain-name-length)),
   printable PrintableString (SIZE (0..ub-domain-name-length)) }

NetworkAddress ::= X121Address  -- see also extended-network-address

X121Address ::= NumericString (SIZE (1..ub-x121-address-length))

TerminalIdentifier ::= PrintableString (SIZE (1..ub-terminal-id-length))

PrivateDomainName ::= CHOICE {



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   numeric NumericString (SIZE (1..ub-domain-name-length)),
   printable PrintableString (SIZE (1..ub-domain-name-length)) }

OrganizationName ::= PrintableString
                            (SIZE (1..ub-organization-name-length))
-- see also teletex-organization-name

NumericUserIdentifier ::= NumericString
                            (SIZE (1..ub-numeric-user-id-length))

PersonalName ::= SET {
   surname [0] PrintableString (SIZE (1..ub-surname-length)),
   given-name [1] PrintableString
                        (SIZE (1..ub-given-name-length)) OPTIONAL,
   initials [2] PrintableString (SIZE (1..ub-initials-length)) OPTIONAL,
   generation-qualifier [3] PrintableString
                (SIZE (1..ub-generation-qualifier-length)) OPTIONAL }
-- see also teletex-personal-name

OrganizationalUnitNames ::= SEQUENCE SIZE (1..ub-organizational-units)
                                        OF OrganizationalUnitName
-- see also teletex-organizational-unit-names

OrganizationalUnitName ::= PrintableString (SIZE
                        (1..ub-organizational-unit-name-length))

--      Built-in Domain-defined Attributes

BuiltInDomainDefinedAttributes ::= SEQUENCE SIZE
                                (1..ub-domain-defined-attributes) OF
                                BuiltInDomainDefinedAttribute

BuiltInDomainDefinedAttribute ::= SEQUENCE {
   type PrintableString (SIZE
                        (1..ub-domain-defined-attribute-type-length)),
   value PrintableString (SIZE
                        (1..ub-domain-defined-attribute-value-length))}

--      Extension Attributes

ExtensionAttributes ::= SET SIZE (1..ub-extension-attributes) OF
                        ExtensionAttribute

ExtensionAttribute ::=  SEQUENCE {
   extension-attribute-type [0] INTEGER (0..ub-extension-attributes),
   extension-attribute-value [1]
                        ANY DEFINED BY extension-attribute-type }




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-- Extension types and attribute values
--

common-name INTEGER ::= 1

CommonName ::= PrintableString (SIZE (1..ub-common-name-length))

teletex-common-name INTEGER ::= 2

TeletexCommonName ::= TeletexString (SIZE (1..ub-common-name-length))

teletex-organization-name INTEGER ::= 3

TeletexOrganizationName ::=
                TeletexString (SIZE (1..ub-organization-name-length))

teletex-personal-name INTEGER ::= 4

TeletexPersonalName ::= SET {
   surname [0] TeletexString (SIZE (1..ub-surname-length)),
   given-name [1] TeletexString
                (SIZE (1..ub-given-name-length)) OPTIONAL,
   initials [2] TeletexString (SIZE (1..ub-initials-length)) OPTIONAL,
   generation-qualifier [3] TeletexString (SIZE
                (1..ub-generation-qualifier-length)) OPTIONAL }

teletex-organizational-unit-names INTEGER ::= 5

TeletexOrganizationalUnitNames ::= SEQUENCE SIZE
        (1..ub-organizational-units) OF TeletexOrganizationalUnitName

TeletexOrganizationalUnitName ::= TeletexString
                        (SIZE (1..ub-organizational-unit-name-length))

pds-name INTEGER ::= 7

PDSName ::= PrintableString (SIZE (1..ub-pds-name-length))

physical-delivery-country-name INTEGER ::= 8

PhysicalDeliveryCountryName ::= CHOICE {
   x121-dcc-code NumericString (SIZE (ub-country-name-numeric-length)),
   iso-3166-alpha2-code PrintableString
                        (SIZE (ub-country-name-alpha-length)) }

postal-code INTEGER ::= 9

PostalCode ::= CHOICE {



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   numeric-code NumericString (SIZE (1..ub-postal-code-length)),
   printable-code PrintableString (SIZE (1..ub-postal-code-length)) }

physical-delivery-office-name INTEGER ::= 10

PhysicalDeliveryOfficeName ::= PDSParameter

physical-delivery-office-number INTEGER ::= 11

PhysicalDeliveryOfficeNumber ::= PDSParameter

extension-OR-address-components INTEGER ::= 12

ExtensionORAddressComponents ::= PDSParameter

physical-delivery-personal-name INTEGER ::= 13

PhysicalDeliveryPersonalName ::= PDSParameter

physical-delivery-organization-name INTEGER ::= 14

PhysicalDeliveryOrganizationName ::= PDSParameter

extension-physical-delivery-address-components INTEGER ::= 15

ExtensionPhysicalDeliveryAddressComponents ::= PDSParameter

unformatted-postal-address INTEGER ::= 16

UnformattedPostalAddress ::= SET {
   printable-address SEQUENCE SIZE (1..ub-pds-physical-address-lines) OF
           PrintableString (SIZE (1..ub-pds-parameter-length)) OPTIONAL,
   teletex-string TeletexString
         (SIZE (1..ub-unformatted-address-length)) OPTIONAL }

street-address INTEGER ::= 17

StreetAddress ::= PDSParameter

post-office-box-address INTEGER ::= 18

PostOfficeBoxAddress ::= PDSParameter

poste-restante-address INTEGER ::= 19

PosteRestanteAddress ::= PDSParameter

unique-postal-name INTEGER ::= 20



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UniquePostalName ::= PDSParameter

local-postal-attributes INTEGER ::= 21

LocalPostalAttributes ::= PDSParameter

PDSParameter ::= SET {
   printable-string PrintableString
                (SIZE(1..ub-pds-parameter-length)) OPTIONAL,
   teletex-string TeletexString
                (SIZE(1..ub-pds-parameter-length)) OPTIONAL }

extended-network-address INTEGER ::= 22

ExtendedNetworkAddress ::= CHOICE {
   e163-4-address SEQUENCE {
        number [0] NumericString (SIZE (1..ub-e163-4-number-length)),
        sub-address [1] NumericString
                (SIZE (1..ub-e163-4-sub-address-length)) OPTIONAL },
   psap-address [0] PresentationAddress }

PresentationAddress ::= SEQUENCE {
        pSelector       [0] EXPLICIT OCTET STRING OPTIONAL,
        sSelector       [1] EXPLICIT OCTET STRING OPTIONAL,
        tSelector       [2] EXPLICIT OCTET STRING OPTIONAL,
        nAddresses      [3] EXPLICIT SET SIZE (1..MAX) OF OCTET STRING }

terminal-type  INTEGER ::= 23

TerminalType ::= INTEGER {
   telex (3),
   teletex (4),
   g3-facsimile (5),
   g4-facsimile (6),
   ia5-terminal (7),
   videotex (8) } (0..ub-integer-options)

--      Extension Domain-defined Attributes

teletex-domain-defined-attributes INTEGER ::= 6

TeletexDomainDefinedAttributes ::= SEQUENCE SIZE
   (1..ub-domain-defined-attributes) OF TeletexDomainDefinedAttribute

TeletexDomainDefinedAttribute ::= SEQUENCE {
        type TeletexString
               (SIZE (1..ub-domain-defined-attribute-type-length)),
        value TeletexString



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               (SIZE (1..ub-domain-defined-attribute-value-length)) }

--  specifications of Upper Bounds shall be regarded as mandatory
--  from Annex B of ITU-T X.411 Reference Definition of MTS Parameter
--  Upper Bounds

--      Upper Bounds
ub-name INTEGER ::=     32768
ub-common-name  INTEGER ::=     64
ub-locality-name        INTEGER ::=     128
ub-state-name   INTEGER ::=     128
ub-organization-name    INTEGER ::=     64
ub-organizational-unit-name     INTEGER ::=     64
ub-title        INTEGER ::=     64
ub-match        INTEGER ::=     128

ub-emailaddress-length INTEGER ::= 128

ub-common-name-length INTEGER ::= 64
ub-country-name-alpha-length INTEGER ::= 2
ub-country-name-numeric-length INTEGER ::= 3
ub-domain-defined-attributes INTEGER ::= 4
ub-domain-defined-attribute-type-length INTEGER ::= 8
ub-domain-defined-attribute-value-length INTEGER ::= 128
ub-domain-name-length INTEGER ::= 16
ub-extension-attributes INTEGER ::= 256
ub-e163-4-number-length INTEGER ::= 15
ub-e163-4-sub-address-length INTEGER ::= 40
ub-generation-qualifier-length INTEGER ::= 3
ub-given-name-length INTEGER ::= 16
ub-initials-length INTEGER ::= 5
ub-integer-options INTEGER ::= 256
ub-numeric-user-id-length INTEGER ::= 32
ub-organization-name-length INTEGER ::= 64
ub-organizational-unit-name-length INTEGER ::= 32
ub-organizational-units INTEGER ::= 4
ub-pds-name-length INTEGER ::= 16
ub-pds-parameter-length INTEGER ::= 30
ub-pds-physical-address-lines INTEGER ::= 6
ub-postal-code-length INTEGER ::= 16
ub-surname-length INTEGER ::= 40
ub-terminal-id-length INTEGER ::= 24
ub-unformatted-address-length INTEGER ::= 180
ub-x121-address-length INTEGER ::= 16

-- Note - upper bounds on string types, such as TeletexString, are
-- measured in characters.  Excepting PrintableString or IA5String, a
-- significantly greater number of octets will be required to hold



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-- such a value.  As a minimum, 16 octets, or twice the specified upper
-- bound, whichever is the larger, should be allowed for TeletexString.
-- For UTF8String or UniversalString at least four times the upper
-- bound should be allowed.

END













































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A.2 Implicitly Tagged Module, 1988 Syntax

PKIX1Implicit88 {iso(1) identified-organization(3) dod(6) internet(1)
  security(5) mechanisms(5) pkix(7) id-mod(0) id-pkix1-implicit-88(2)}

DEFINITIONS IMPLICIT TAGS ::=

BEGIN

-- EXPORTS ALL --

IMPORTS
        id-pkix, id-pe, id-qt, id-kp, id-qt-unotice, id-qt-cps,
            id-ad, id-ad-ocsp, id-ad-caIssuers,
            -- delete following line if "new" types are supported --
            BMPString, UniversalString, UTF8String, -- end "new" types
                ORAddress, Name, RelativeDistinguishedName,
                CertificateSerialNumber,
                CertificateList, AlgorithmIdentifier, ub-name,
                Attribute, DirectoryString
                FROM PKIX1Explicit88 {iso(1) identified-organization(3)
                dod(6) internet(1) security(5) mechanisms(5) pkix(7)
                id-mod(0) id-pkix1-explicit(1)};


-- ISO arc for standard certificate and CRL extensions

id-ce OBJECT IDENTIFIER  ::=  {joint-iso-ccitt(2) ds(5) 29}

-- authority key identifier OID and syntax

id-ce-authorityKeyIdentifier OBJECT IDENTIFIER ::=  { id-ce 35 }

AuthorityKeyIdentifier ::= SEQUENCE {
      keyIdentifier             [0] KeyIdentifier            OPTIONAL,
      authorityCertIssuer       [1] GeneralNames             OPTIONAL,
      authorityCertSerialNumber [2] CertificateSerialNumber  OPTIONAL }
    -- authorityCertIssuer and authorityCertSerialNumber shall both
    -- be present or both be absent

KeyIdentifier ::= OCTET STRING

-- subject key identifier OID and syntax

id-ce-subjectKeyIdentifier OBJECT IDENTIFIER ::=  { id-ce 14 }

SubjectKeyIdentifier ::= KeyIdentifier




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-- key usage extension OID and syntax

id-ce-keyUsage OBJECT IDENTIFIER ::=  { id-ce 15 }

KeyUsage ::= BIT STRING {
     digitalSignature        (0),
     nonRepudiation          (1),
     keyEncipherment         (2),
     dataEncipherment        (3),
     keyAgreement            (4),
     keyCertSign             (5),
     cRLSign                 (6),
     encipherOnly            (7),
     decipherOnly            (8) }

-- private key usage period extension OID and syntax

id-ce-privateKeyUsagePeriod OBJECT IDENTIFIER ::=  { id-ce 16 }

PrivateKeyUsagePeriod ::= SEQUENCE {
     notBefore       [0]     GeneralizedTime OPTIONAL,
     notAfter        [1]     GeneralizedTime OPTIONAL }
     -- either notBefore or notAfter shall be present

-- certificate policies extension OID and syntax

id-ce-certificatePolicies OBJECT IDENTIFIER ::=  { id-ce 32 }

CertificatePolicies ::= SEQUENCE SIZE (1..MAX) OF PolicyInformation

PolicyInformation ::= SEQUENCE {
     policyIdentifier   CertPolicyId,
     policyQualifiers   SEQUENCE SIZE (1..MAX) OF
             PolicyQualifierInfo OPTIONAL }

CertPolicyId ::= OBJECT IDENTIFIER

PolicyQualifierInfo ::= SEQUENCE {
       policyQualifierId  PolicyQualifierId,
       qualifier        ANY DEFINED BY policyQualifierId }

-- Implementations that recognize additional policy qualifiers shall
-- augment the following definition for PolicyQualifierId

PolicyQualifierId ::=
    OBJECT IDENTIFIER ( id-qt-cps | id-qt-unotice )

-- CPS pointer qualifier



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CPSuri ::= IA5String

-- user notice qualifier

UserNotice ::= SEQUENCE {
     noticeRef        NoticeReference OPTIONAL,
     explicitText     DisplayText OPTIONAL}

NoticeReference ::= SEQUENCE {
     organization     DisplayText,
     noticeNumbers    SEQUENCE OF INTEGER }

DisplayText ::= CHOICE {
     visibleString    VisibleString  (SIZE (1..200)),
     bmpString        BMPString      (SIZE (1..200)),
     utf8String       UTF8String     (SIZE (1..200)) }

-- policy mapping extension OID and syntax

id-ce-policyMappings OBJECT IDENTIFIER ::=  { id-ce 33 }

PolicyMappings ::= SEQUENCE SIZE (1..MAX) OF SEQUENCE {
     issuerDomainPolicy      CertPolicyId,
     subjectDomainPolicy     CertPolicyId }

-- subject alternative name extension OID and syntax

id-ce-subjectAltName OBJECT IDENTIFIER ::=  { id-ce 17 }

SubjectAltName ::= GeneralNames

GeneralNames ::= SEQUENCE SIZE (1..MAX) OF GeneralName

GeneralName ::= CHOICE {
     otherName                       [0]     AnotherName,
     rfc822Name                      [1]     IA5String,
     dNSName                         [2]     IA5String,
     x400Address                     [3]     ORAddress,
     directoryName                   [4]     Name,
     ediPartyName                    [5]     EDIPartyName,
     uniformResourceIdentifier       [6]     IA5String,
     iPAddress                       [7]     OCTET STRING,
     registeredID                    [8]     OBJECT IDENTIFIER }

-- AnotherName replaces OTHER-NAME ::= TYPE-IDENTIFIER, as
-- TYPE-IDENTIFIER is not supported in the '88 ASN.1 syntax

AnotherName ::= SEQUENCE {



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     type-id    OBJECT IDENTIFIER,
     value      [0] EXPLICIT ANY DEFINED BY type-id }

EDIPartyName ::= SEQUENCE {
     nameAssigner            [0]     DirectoryString OPTIONAL,
     partyName               [1]     DirectoryString }

-- issuer alternative name extension OID and syntax

id-ce-issuerAltName OBJECT IDENTIFIER ::=  { id-ce 18 }

IssuerAltName ::= GeneralNames

id-ce-subjectDirectoryAttributes OBJECT IDENTIFIER ::=  { id-ce 9 }

SubjectDirectoryAttributes ::= SEQUENCE SIZE (1..MAX) OF Attribute

-- basic constraints extension OID and syntax

id-ce-basicConstraints OBJECT IDENTIFIER ::=  { id-ce 19 }

BasicConstraints ::= SEQUENCE {
     cA                      BOOLEAN DEFAULT FALSE,
     pathLenConstraint       INTEGER (0..MAX) OPTIONAL }

-- name constraints extension OID and syntax

id-ce-nameConstraints OBJECT IDENTIFIER ::=  { id-ce 30 }

NameConstraints ::= SEQUENCE {
     permittedSubtrees       [0]     GeneralSubtrees OPTIONAL,
     excludedSubtrees        [1]     GeneralSubtrees OPTIONAL }

GeneralSubtrees ::= SEQUENCE SIZE (1..MAX) OF GeneralSubtree

GeneralSubtree ::= SEQUENCE {
     base                    GeneralName,
     minimum         [0]     BaseDistance DEFAULT 0,
     maximum         [1]     BaseDistance OPTIONAL }

BaseDistance ::= INTEGER (0..MAX)

-- policy constraints extension OID and syntax

id-ce-policyConstraints OBJECT IDENTIFIER ::=  { id-ce 36 }

PolicyConstraints ::= SEQUENCE {
     requireExplicitPolicy           [0] SkipCerts OPTIONAL,



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     inhibitPolicyMapping            [1] SkipCerts OPTIONAL }

SkipCerts ::= INTEGER (0..MAX)

-- CRL distribution points extension OID and syntax

id-ce-cRLDistributionPoints     OBJECT IDENTIFIER  ::=  {id-ce 31}

CRLDistPointsSyntax ::= SEQUENCE SIZE (1..MAX) OF DistributionPoint

DistributionPoint ::= SEQUENCE {
     distributionPoint       [0]     DistributionPointName OPTIONAL,
     reasons                 [1]     ReasonFlags OPTIONAL,
     cRLIssuer               [2]     GeneralNames OPTIONAL }

DistributionPointName ::= CHOICE {
     fullName                [0]     GeneralNames,
     nameRelativeToCRLIssuer [1]     RelativeDistinguishedName }

ReasonFlags ::= BIT STRING {
     unused                  (0),
     keyCompromise           (1),
     cACompromise            (2),
     affiliationChanged      (3),
     superseded              (4),
     cessationOfOperation    (5),
     certificateHold         (6) }

-- extended key usage extension OID and syntax

id-ce-extKeyUsage OBJECT IDENTIFIER ::= {id-ce 37}

ExtKeyUsageSyntax ::= SEQUENCE SIZE (1..MAX) OF KeyPurposeId

KeyPurposeId ::= OBJECT IDENTIFIER

-- extended key purpose OIDs
id-kp-serverAuth      OBJECT IDENTIFIER ::= { id-kp 1 }
id-kp-clientAuth      OBJECT IDENTIFIER ::= { id-kp 2 }
id-kp-codeSigning     OBJECT IDENTIFIER ::= { id-kp 3 }
id-kp-emailProtection OBJECT IDENTIFIER ::= { id-kp 4 }
id-kp-ipsecEndSystem  OBJECT IDENTIFIER ::= { id-kp 5 }
id-kp-ipsecTunnel     OBJECT IDENTIFIER ::= { id-kp 6 }
id-kp-ipsecUser       OBJECT IDENTIFIER ::= { id-kp 7 }
id-kp-timeStamping    OBJECT IDENTIFIER ::= { id-kp 8 }

-- authority info access




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id-pe-authorityInfoAccess OBJECT IDENTIFIER ::= { id-pe 1 }

AuthorityInfoAccessSyntax  ::=
        SEQUENCE SIZE (1..MAX) OF AccessDescription

AccessDescription  ::=  SEQUENCE {
        accessMethod          OBJECT IDENTIFIER,
        accessLocation        GeneralName  }

-- CRL number extension OID and syntax

id-ce-cRLNumber OBJECT IDENTIFIER ::= { id-ce 20 }

CRLNumber ::= INTEGER (0..MAX)

-- issuing distribution point extension OID and syntax

id-ce-issuingDistributionPoint OBJECT IDENTIFIER ::= { id-ce 28 }

IssuingDistributionPoint ::= SEQUENCE {
     distributionPoint       [0] DistributionPointName OPTIONAL,
     onlyContainsUserCerts   [1] BOOLEAN DEFAULT FALSE,
     onlyContainsCACerts     [2] BOOLEAN DEFAULT FALSE,
     onlySomeReasons         [3] ReasonFlags OPTIONAL,
     indirectCRL             [4] BOOLEAN DEFAULT FALSE }


id-ce-deltaCRLIndicator OBJECT IDENTIFIER ::= { id-ce 27 }

-- deltaCRLIndicator ::= BaseCRLNumber

BaseCRLNumber ::= CRLNumber

-- CRL reasons extension OID and syntax

id-ce-cRLReasons OBJECT IDENTIFIER ::= { id-ce 21 }

CRLReason ::= ENUMERATED {
     unspecified             (0),
     keyCompromise           (1),
     cACompromise            (2),
     affiliationChanged      (3),
     superseded              (4),
     cessationOfOperation    (5),
     certificateHold         (6),
     removeFromCRL           (8) }

-- certificate issuer CRL entry extension OID and syntax



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id-ce-certificateIssuer OBJECT IDENTIFIER ::= { id-ce 29 }

CertificateIssuer ::= GeneralNames

-- hold instruction extension OID and syntax

id-ce-holdInstructionCode OBJECT IDENTIFIER ::= { id-ce 23 }

HoldInstructionCode ::= OBJECT IDENTIFIER

-- ANSI x9 holdinstructions

-- ANSI x9 arc holdinstruction arc
holdInstruction OBJECT IDENTIFIER ::=
          {joint-iso-itu-t(2) member-body(2) us(840) x9cm(10040) 2}

-- ANSI X9 holdinstructions referenced by this standard
id-holdinstruction-none OBJECT IDENTIFIER  ::=
                {holdInstruction 1} -- deprecated
id-holdinstruction-callissuer OBJECT IDENTIFIER ::=
                {holdInstruction 2}
id-holdinstruction-reject OBJECT IDENTIFIER ::=
                {holdInstruction 3}

-- invalidity date CRL entry extension OID and syntax

id-ce-invalidityDate OBJECT IDENTIFIER ::= { id-ce 24 }

InvalidityDate ::=  GeneralizedTime

END




















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Appendix B. 1993 ASN.1 Structures and OIDs


B.1 Explicitly Tagged Module, 1993 Syntax

PKIX1Explicit93 {iso(1) identified-organization(3) dod(6) internet(1)
   security(5) mechanisms(5) pkix(7) id-mod(0) id-pkix1-explicit-93(3)}


DEFINITIONS EXPLICIT TAGS ::=

BEGIN

-- EXPORTS ALL --

IMPORTS
        authorityKeyIdentifier, subjectKeyIdentifier, keyUsage,
           extendedKeyUsage, privateKeyUsagePeriod, certificatePolicies,
           policyMappings, subjectAltName, issuerAltName,
           basicConstraints, nameConstraints, policyConstraints,
           cRLDistributionPoints, subjectDirectoryAttributes,
           cRLNumber, reasonCode, instructionCode, invalidityDate,
           issuingDistributionPoint, certificateIssuer,
           deltaCRLIndicator, authorityInfoAccess, id-ce
           FROM PKIX1Implicit93 {iso(1) identified-organization(3)
           dod(6) internet(1) security(5) mechanisms(5) pkix(7)
           id-mod(0) id-pkix1-implicit-93(4)} ;

--
                   --  Locally defined OIDs  --

id-pkix  OBJECT IDENTIFIER  ::=
         { iso(1) identified-organization(3) dod(6) internet(1)
                    security(5) mechanisms(5) pkix(7) }

-- PKIX arcs
-- arc for private certificate extensions
id-pe OBJECT IDENTIFIER  ::=  { id-pkix 1 }
 -- arc for policy qualifier types
id-qt OBJECT IDENTIFIER ::= { id-pkix 2 }
-- arc for extended key purpose OIDS
id-kp OBJECT IDENTIFIER ::= { id-pkix 3 }
-- arc for access descriptors
id-ad OBJECT IDENTIFIER ::= { id-pkix 48 }

-- policyQualifierIds for Internet policy qualifiers
id-qt-cps      OBJECT IDENTIFIER ::=  { id-qt 1 }
        -- OID for CPS qualifier



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id-qt-unotice  OBJECT IDENTIFIER ::=  { id-qt 2 }
        -- OID for user notice qualifier

-- based on excerpts from AuthenticationFramework
--    {joint-iso-ccitt ds(5) modules(1) authenticationFramework(7) 2}

               -- Public Key Certificate --

Certificate            ::=   SIGNED { SEQUENCE {
   version                 [0]   Version DEFAULT v1,
   serialNumber                  CertificateSerialNumber,
   signature                     AlgorithmIdentifier,
   issuer                        Name,
   validity                      Validity,
   subject                       Name,
   subjectPublicKeyInfo          SubjectPublicKeyInfo,
   issuerUniqueIdentifier  [1]   IMPLICIT UniqueIdentifier OPTIONAL,
                              ---if present, version shall be v2 or v3--
   subjectUniqueIdentifier [2]   IMPLICIT UniqueIdentifier OPTIONAL,
                              ---if present, version shall be v2 or v3--
   extensions              [3]   Extensions OPTIONAL
                              --if present, version shall be v3--}  }

UniqueIdentifier        ::=  BIT STRING

Version                 ::=  INTEGER { v1(0), v2(1), v3(2) }

CertificateSerialNumber ::=  INTEGER

Validity                        ::=     SEQUENCE {
   notBefore            Time,
   notAfter             Time }

Time ::= CHOICE {
        utcTime         UTCTime,
        generalTime             GeneralizedTime }

SubjectPublicKeyInfo    ::=     SEQUENCE{
   algorithm            AlgorithmIdentifier,
   subjectPublicKey     BIT STRING}

Extensions        ::=   SEQUENCE SIZE (1..MAX) OF Extension

Extension         ::=   SEQUENCE {
   extnId            EXTENSION.&id ({ExtensionSet}),
   critical          BOOLEAN DEFAULT FALSE,
   extnValue         OCTET STRING }
                -- contains a DER encoding of a value of type



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                -- &ExtnType for the
                -- extension object identified by extnId --

-- The following information object set is defined to constrain the
-- set of legal certificate extensions.

ExtensionSet    EXTENSION       ::=     { authorityKeyIdentifier |
                                        subjectKeyIdentifier |
                                        keyUsage |
                                        extendedKeyUsage |
                                        privateKeyUsagePeriod |
                                        certificatePolicies |
                                        policyMappings |
                                        subjectAltName |
                                        issuerAltName |
                                        basicConstraints |
                                        nameConstraints |
                                        policyConstraints |
                                        cRLDistributionPoints |
                                        subjectDirectoryAttributes |
                                        authorityInfoAccess }

EXTENSION       ::=     CLASS {
   &id          OBJECT IDENTIFIER UNIQUE,
   &ExtnType }
WITH SYNTAX  {
   SYNTAX               &ExtnType
   IDENTIFIED BY        &id }

                  -- Certificate Revocation List --

CertificateList ::=    SIGNED { SEQUENCE {
   version                Version  OPTIONAL, -- if present, shall be v2
   signature              AlgorithmIdentifier,
   issuer                 Name,
   thisUpdate             Time,
   nextUpdate             Time OPTIONAL,
   revokedCertificates    SEQUENCE OF SEQUENCE {
   userCertificate        CertificateSerialNumber,
   revocationDate         Time,
   crlEntryExtensions     EntryExtensions OPTIONAL } OPTIONAL,
   crlExtensions          [0]   CRLExtensions OPTIONAL }}

CRLExtensions        ::=        SEQUENCE SIZE (1..MAX) OF CRLExtension

CRLExtension         ::=        SEQUENCE {
   extnId            EXTENSION.&id ({CRLExtensionSet}),
   critical          BOOLEAN DEFAULT FALSE,



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   extnValue         OCTET STRING }
                -- contains a DER encoding of a value of type
                -- &ExtnType for the
                -- extension object identified by extnId --

-- The following information object set is defined to constrain the
-- set of legal CRL extensions.

CRLExtensionSet EXTENSION       ::=     { authorityKeyIdentifier |
                                        issuerAltName |
                                        cRLNumber |
                                        deltaCRLIndicator |
                                        issuingDistributionPoint }

-- EXTENSION defined above for certificates

EntryExtensions        ::=      SEQUENCE SIZE (1..MAX) OF EntryExtension

EntryExtension         ::=      SEQUENCE {
   extnId            EXTENSION.&id ({EntryExtensionSet}),
   critical          BOOLEAN DEFAULT FALSE,
   extnValue         OCTET STRING }
                -- contains a DER encoding of a value of type
                -- &ExtnType for the
                -- extension object identified by extnId --

-- The following information object set is defined to constrain the
-- set of legal CRL entry extensions.

EntryExtensionSet       EXTENSION       ::=     { reasonCode |
                                                instructionCode |
                                                invalidityDate |
                                                certificateIssuer }

         -- information object classes used in the defintion --
                    -- of certificates and CRLs --

-- Parameterized Type SIGNED --

  SIGNED { ToBeSigned } ::= SEQUENCE {
     toBeSigned  ToBeSigned,
     algorithm   AlgorithmIdentifier,
     signature   BIT STRING
  }

-- Definition of AlgorithmIdentifier
-- ISO definition was:
--



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-- AlgorithmIdentifier     ::=  SEQUENCE {
--   algorithm          ALGORITHM.&id({SupportedAlgorithms}),
--   parameters         ALGORITHM.&Type({SupportedAlgorithms}
--                                         { @algorithm}) OPTIONAL }
-- Definition of ALGORITHM
-- ALGORITHM    ::=     TYPE-IDENTIFIER

-- The following PKIX definition replaces the X.509 definition
--

AlgorithmIdentifier     ::=  SEQUENCE {
   algorithm            ALGORITHM-ID.&id({SupportedAlgorithms}),
   parameters           ALGORITHM-ID.&Type({SupportedAlgorithms}
                                           { @algorithm}) OPTIONAL }

-- Definition of ALGORITHM-ID

 ALGORITHM-ID ::= CLASS {
     &id    OBJECT IDENTIFIER UNIQUE,
     &Type  OPTIONAL
  }
     WITH SYNTAX { OID &id [PARMS &Type] }

-- The definition of SupportedAlgorithms may be modified as this
-- document does not specify a mandatory algorithm set.  In addition,
-- the set is specified as extensible, since additional algorithms
-- may be supported

SupportedAlgorithms     ALGORITHM-ID  ::=       { ..., -- extensible
                                            rsaPublicKey |
                                            rsaSHA-1  |
                                            rsaMD5 |
                                            rsaMD2 |
                                            dssPublicKey |
                                            dsaSHA-1 |
                                            dhPublicKey }

-- OIDs and parameter structures for ALGORITHM-IDs used
-- in this specification

rsaPublicKey ALGORITHM-ID ::= { OID rsaEncryption PARMS NULL }

rsaSHA-1 ALGORITHM-ID ::= { OID sha1WithRSAEncryption PARMS NULL }

rsaMD5 ALGORITHM-ID ::= { OID md5WithRSAEncryption PARMS NULL  }

rsaMD2 ALGORITHM-ID ::= { OID md2WithRSAEncryption PARMS NULL  }




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dssPublicKey ALGORITHM-ID ::= { OID id-dsa PARMS Dss-Parms }

dsaSHA-1 ALGORITHM-ID ::= { OID id-dsa-with-sha1 }

dhPublicKey ALGORITHM-ID ::= {OID dhpublicnumber PARMS DomainParameters}

-- algorithm identifiers and parameter structures

pkcs-1 OBJECT IDENTIFIER ::= {
     iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) 1 }

rsaEncryption OBJECT IDENTIFIER ::=  { pkcs-1 1 }

md2WithRSAEncryption OBJECT IDENTIFIER  ::=  { pkcs-1 2 }

md5WithRSAEncryption OBJECT IDENTIFIER  ::=  { pkcs-1 4 }

sha1WithRSAEncryption OBJECT IDENTIFIER  ::=  { pkcs-1 5 }

id-dsa-with-sha1 OBJECT IDENTIFIER ::=  {
     iso(1) member-body(2) us(840) x9-57 (10040) x9algorithm(4) 3 }

Dss-Sig-Value  ::=  SEQUENCE  {
     r       INTEGER,
     s       INTEGER  }

dhpublicnumber OBJECT IDENTIFIER ::= {
     iso(1) member-body(2) us(840) ansi-x942(10046) number-type(2) 1 }

DomainParameters ::= SEQUENCE {
     p       INTEGER, -- odd prime, p=jq +1
     g       INTEGER, -- generator, g
     q       INTEGER, -- factor of p-1
     j       INTEGER OPTIONAL, -- subgroup factor, j>= 2
     validationParms  ValidationParms OPTIONAL }

ValidationParms ::= SEQUENCE {
     seed             BIT STRING,
     pgenCounter      INTEGER }

id-dsa OBJECT IDENTIFIER ::= {
     iso(1) member-body(2) us(840) x9-57(10040) x9algorithm(4) 1 }

Dss-Parms  ::=  SEQUENCE  {
     p             INTEGER,
     q             INTEGER,
     g             INTEGER  }




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     -- The ASN.1 in this section supports the Name type
     -- and the directoryAttribute extension

-- attribute data types --

Attribute       ::=     SEQUENCE {
        type            ATTRIBUTE.&id ({SupportedAttributes}),
        values  SET SIZE (1 .. MAX) OF ATTRIBUTE.&Type
                        ({SupportedAttributes}{@type})}

AttributeTypeAndValue           ::=     SEQUENCE {
        type            ATTRIBUTE.&id ({SupportedAttributes}),
        value   ATTRIBUTE.&Type ({SupportedAttributes}{@type})}

-- naming data types --

Name            ::=     CHOICE { -- only one possibility for now --
                                        rdnSequence  RDNSequence }

RDNSequence ::= SEQUENCE OF RelativeDistinguishedName

RelativeDistinguishedName       ::=
                SET SIZE (1 .. MAX) OF AttributeTypeAndValue

ID     ::=    OBJECT IDENTIFIER

-- ATTRIBUTE information object class specification
--  Note: This has been greatly simplified for PKIX !!

ATTRIBUTE               ::=     CLASS {
        &Type,
        &id                     OBJECT IDENTIFIER UNIQUE }
WITH SYNTAX {
        WITH SYNTAX &Type ID &id }

-- suggested naming attributes
--      Definition of the following information object set may be
--    augmented to meet local requirements.  Note that deleting
--    members of the set may prevent interoperability with
--    conforming implementations.

SupportedAttributes     ATTRIBUTE       ::=     {
                name | commonName | surname | givenName | initials |
                generationQualifier | dnQualifier | countryName |
                localityName | stateOrProvinceName | organizationName |
                        organizationalUnitName | title | pkcs9email }

name ATTRIBUTE  ::=     {



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        WITH SYNTAX                     DirectoryString { ub-name }
        ID                              id-at-name }

commonName ATTRIBUTE    ::=     {
        WITH SYNTAX                     DirectoryString {ub-common-name}
        ID                              id-at-commonName }

surname ATTRIBUTE       ::=             {
        WITH SYNTAX                     DirectoryString {ub-name}
        ID                              id-at-surname }

givenName ATTRIBUTE     ::=             {
        WITH SYNTAX                     DirectoryString {ub-name}
        ID                              id-at-givenName }

initials ATTRIBUTE      ::=             {
        WITH SYNTAX                     DirectoryString {ub-name}
        ID                              id-at-initials }

generationQualifier ATTRIBUTE   ::=             {
        WITH SYNTAX                     DirectoryString {ub-name}
        ID                              id-at-generationQualifier}

dnQualifier ATTRIBUTE   ::=     {
        WITH SYNTAX                     PrintableString
        ID                              id-at-dnQualifier }


countryName ATTRIBUTE   ::=     {
        WITH SYNTAX                     PrintableString (SIZE (2))
                                                -- IS 3166 codes only
        ID                              id-at-countryName }

localityName ATTRIBUTE  ::=     {
        WITH SYNTAX             DirectoryString {ub-locality-name}
        ID                      id-at-localityName }

stateOrProvinceName ATTRIBUTE   ::=     {
        WITH SYNTAX             DirectoryString {ub-state-name}
        ID                      id-at-stateOrProvinceName }

organizationName ATTRIBUTE      ::=     {
        WITH SYNTAX             DirectoryString {ub-organization-name}
        ID                      id-at-organizationName }

organizationalUnitName ATTRIBUTE        ::=     {
        WITH SYNTAX  DirectoryString {ub-organizational-unit-name}
        ID                      id-at-organizationalUnitName }



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title ATTRIBUTE ::=                     {
        WITH SYNTAX             DirectoryString {ub-title}
        ID                      id-at-title }

 -- Legacy attributes

pkcs9email ATTRIBUTE ::= {
        WITH SYNTAX                     PHGString,
        ID                              emailAddress }

PHGString ::= IA5String (SIZE(1..ub-emailaddress-length))

pkcs-9 OBJECT IDENTIFIER ::=
       { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) 9 }

emailAddress OBJECT IDENTIFIER ::= { pkcs-9 1 }

    -- object identifiers for Name type and directory attribute support

-- Object identifier assignments --

id-at   OBJECT IDENTIFIER       ::=     {joint-iso-ccitt(2) ds(5) 4}

-- Attributes --

id-at-commonName        OBJECT IDENTIFIER       ::=     {id-at 3}
id-at-surname           OBJECT IDENTIFIER       ::=     {id-at 4}
id-at-countryName       OBJECT IDENTIFIER       ::=     {id-at 6}
id-at-localityName      OBJECT IDENTIFIER       ::=     {id-at 7}
id-at-stateOrProvinceName     OBJECT IDENTIFIER ::= {id-at 8}
id-at-organizationName        OBJECT IDENTIFIER ::= {id-at 10}
id-at-organizationalUnitName  OBJECT IDENTIFIER ::= {id-at 11}
id-at-title             OBJECT IDENTIFIER       ::=     {id-at 12}
id-at-name              OBJECT IDENTIFIER       ::=     {id-at 41}
id-at-givenName         OBJECT IDENTIFIER       ::=     {id-at 42}
id-at-initials          OBJECT IDENTIFIER       ::=     {id-at 43}
id-at-generationQualifier   OBJECT IDENTIFIER   ::=     {id-at 44}
id-at-dnQualifier       OBJECT IDENTIFIER       ::=     {id-at 46}

-- Directory string type, used extensively in Name types --

DirectoryString { INTEGER:maxSize } ::= CHOICE {
        teletexString           TeletexString (SIZE (1..maxSize)),
        printableString         PrintableString (SIZE (1..maxSize)),
        universalString         UniversalString (SIZE (1..maxSize)),
        bmpString               BMPString (SIZE(1..maxSize)),
        utf8String              UTF8String (SIZE(1..maxSize))
                            }



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RFC 2459        Internet X.509 Public Key Infrastructure    January 1999


     -- End of ASN.1 for Name type and directory attribute support --

     -- The ASN.1 in this section supports X.400 style names   --
     -- for implementations that use the x400Address component --
     -- of GeneralName.                                        --

ORAddress ::= SEQUENCE {
   built-in-standard-attributes BuiltInStandardAttributes,
   built-in-domain-defined-attributes
                        BuiltInDomainDefinedAttributes OPTIONAL,
   -- see also teletex-domain-defined-attributes
   extension-attributes ExtensionAttributes OPTIONAL }

--  The OR-address is semantically absent from the OR-name if the
--  built-in-standard-attribute sequence is empty and the
--  built-in-domain-defined-attributes and extension-attributes are
--  both omitted.

--      Built-in Standard Attributes

BuiltInStandardAttributes ::= SEQUENCE {
   country-name CountryName OPTIONAL,
   administration-domain-name AdministrationDomainName OPTIONAL,
   network-address      [0] NetworkAddress OPTIONAL,
   -- see also extended-network-address
   terminal-identifier  [1] TerminalIdentifier OPTIONAL,
   private-domain-name  [2] PrivateDomainName OPTIONAL,
   organization-name    [3] OrganizationName OPTIONAL,
   -- see also teletex-organization-name
   numeric-user-identifier      [4] NumericUserIdentifier OPTIONAL,
   personal-name        [5] PersonalName OPTIONAL,
   -- see also teletex-personal-name
   organizational-unit-names    [6] OrganizationalUnitNames OPTIONAL
   -- see also teletex-organizational-unit-names -- }

CountryName ::= [APPLICATION 1] CHOICE {
   x121-dcc-code NumericString
                (SIZE (ub-country-name-numeric-length)),
   iso-3166-alpha2-code PrintableString
                (SIZE (ub-country-name-alpha-length)) }

AdministrationDomainName ::= [APPLICATION 2] CHOICE {
   numeric NumericString (SIZE (0..ub-domain-name-length)),
   printable PrintableString (SIZE (0..ub-domain-name-length)) }

NetworkAddress ::= X121Address
-- see also extended-network-address




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RFC 2459        Internet X.509 Public Key Infrastructure    January 1999


X121Address ::= NumericString (SIZE (1..ub-x121-address-length))

TerminalIdentifier ::= PrintableString (SIZE (1..ub-terminal-id-length))

PrivateDomainName ::= CHOICE {
   numeric NumericString (SIZE (1..ub-domain-name-length)),
   printable PrintableString (SIZE (1..ub-domain-name-length)) }

OrganizationName ::= PrintableString
                           (SIZE (1..ub-organization-name-length))
-- see also teletex-organization-name

NumericUserIdentifier ::= NumericString
                             (SIZE (1..ub-numeric-user-id-length))

PersonalName ::= SET {
   surname    [0] PrintableString (SIZE (1..ub-surname-length)),
   given-name [1] PrintableString
                        (SIZE (1..ub-given-name-length)) OPTIONAL,
   initials   [2] PrintableString
                        (SIZE (1..ub-initials-length)) OPTIONAL,
   generation-qualifier [3] PrintableString
                (SIZE (1..ub-generation-qualifier-length)) OPTIONAL}
-- see also teletex-personal-name

OrganizationalUnitNames ::= SEQUENCE SIZE (1..ub-organizational-units)
                                        OF OrganizationalUnitName
-- see also teletex-organizational-unit-names

OrganizationalUnitName ::= PrintableString (SIZE
                        (1..ub-organizational-unit-name-length))

--      Built-in Domain-defined Attributes
BuiltInDomainDefinedAttributes ::= SEQUENCE SIZE
                                (1..ub-domain-defined-attributes) OF
                                BuiltInDomainDefinedAttribute

BuiltInDomainDefinedAttribute ::= SEQUENCE {
   type PrintableString (SIZE
                (1..ub-domain-defined-attribute-type-length)),
   value PrintableString (SIZE
                (1..ub-domain-defined-attribute-value-length)) }

--      Extension Attributes

ExtensionAttributes ::= SET SIZE (1..ub-extension-attributes)
                                        OF ExtensionAttribute
ExtensionAttribute ::= SEQUENCE {



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RFC 2459        Internet X.509 Public Key Infrastructure    January 1999


        extension-attribute-type [0] EXTENSION-ATTRIBUTE.&id
                                        ({ExtensionAttributeTable}),
        extension-attribute-value [1] EXTENSION-ATTRIBUTE.&Type
             ({ExtensionAttributeTable} {@extension-attribute-type}) }

EXTENSION-ATTRIBUTE ::= CLASS {
        &id     INTEGER (0..ub-extension-attributes) UNIQUE,
        &Type }
WITH SYNTAX {&Type IDENTIFIED BY &id}

ExtensionAttributeTable EXTENSION-ATTRIBUTE ::= {
        common-name |
        teletex-common-name |
        teletex-organization-name |
        teletex-personal-name |
        teletex-organizational-unit-names |
        teletex-domain-defined-attributes |
        pds-name |
        physical-delivery-country-name |
        postal-code |
        physical-delivery-office-name |
        physical-delivery-office-number |
        extension-OR-address-components |
        physical-delivery-personal-name |
        physical-delivery-organization-name |
        extension-physical-delivery-address-components |
        unformatted-postal-address |
        street-address |
        post-office-box-address |
        poste-restante-address |
        unique-postal-name |
        local-postal-attributes |
        extended-network-address |
        terminal-type }

--      Extension Standard Attributes

common-name EXTENSION-ATTRIBUTE ::= {CommonName IDENTIFIED BY 1}

CommonName ::= PrintableString (SIZE (1..ub-common-name-length))

teletex-common-name EXTENSION-ATTRIBUTE ::=
                {TeletexCommonName IDENTIFIED BY 2}

TeletexCommonName ::= TeletexString (SIZE (1..ub-common-name-length))

teletex-organization-name EXTENSION-ATTRIBUTE ::=
                {TeletexOrganizationName IDENTIFIED BY 3}



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RFC 2459        Internet X.509 Public Key Infrastructure    January 1999


TeletexOrganizationName ::=
                TeletexString (SIZE (1..ub-organization-name-length))

teletex-personal-name EXTENSION-ATTRIBUTE ::=
                {TeletexPersonalName IDENTIFIED BY 4}

TeletexPersonalName ::= SET {
   surname [0] TeletexString (SIZE (1..ub-surname-length)),
   given-name [1] TeletexString
                (SIZE (1..ub-given-name-length)) OPTIONAL,
   initials [2] TeletexString (SIZE (1..ub-initials-length)) OPTIONAL,
   generation-qualifier [3] TeletexString (SIZE
                (1..ub-generation-qualifier-length)) OPTIONAL }

teletex-organizational-unit-names EXTENSION-ATTRIBUTE ::=
   {TeletexOrganizationalUnitNames IDENTIFIED BY 5}

TeletexOrganizationalUnitNames ::= SEQUENCE SIZE
        (1..ub-organizational-units) OF TeletexOrganizationalUnitName

TeletexOrganizationalUnitName ::= TeletexString
                        (SIZE (1..ub-organizational-unit-name-length))

pds-name EXTENSION-ATTRIBUTE ::= {PDSName IDENTIFIED BY 7}

PDSName ::= PrintableString (SIZE (1..ub-pds-name-length))

physical-delivery-country-name EXTENSION-ATTRIBUTE ::=
   {PhysicalDeliveryCountryName IDENTIFIED BY 8}

PhysicalDeliveryCountryName ::= CHOICE {
   x121-dcc-code NumericString (SIZE (ub-country-name-numeric-length)),
   iso-3166-alpha2-code PrintableString
                        (SIZE (ub-country-name-alpha-length)) }

postal-code EXTENSION-ATTRIBUTE ::= {PostalCode IDENTIFIED BY 9}

PostalCode ::= CHOICE {
   numeric-code NumericString (SIZE (1..ub-postal-code-length)),
   printable-code PrintableString (SIZE (1..ub-postal-code-length)) }

physical-delivery-office-name EXTENSION-ATTRIBUTE ::=
                        {PhysicalDeliveryOfficeName IDENTIFIED BY 10}

PhysicalDeliveryOfficeName ::= PDSParameter

physical-delivery-office-number EXTENSION-ATTRIBUTE ::=
   {PhysicalDeliveryOfficeNumber IDENTIFIED BY 11}



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RFC 2459        Internet X.509 Public Key Infrastructure    January 1999


PhysicalDeliveryOfficeNumber ::= PDSParameter

extension-OR-address-components EXTENSION-ATTRIBUTE ::=
   {ExtensionORAddressComponents IDENTIFIED BY 12}

ExtensionORAddressComponents ::= PDSParameter

physical-delivery-personal-name EXTENSION-ATTRIBUTE ::=
   {PhysicalDeliveryPersonalName IDENTIFIED BY 13}

PhysicalDeliveryPersonalName ::= PDSParameter

physical-delivery-organization-name EXTENSION-ATTRIBUTE ::=
   {PhysicalDeliveryOrganizationName IDENTIFIED BY 14}

PhysicalDeliveryOrganizationName ::= PDSParameter

extension-physical-delivery-address-components EXTENSION-ATTRIBUTE ::=
   {ExtensionPhysicalDeliveryAddressComponents IDENTIFIED BY 15}

ExtensionPhysicalDeliveryAddressComponents ::= PDSParameter

unformatted-postal-address EXTENSION-ATTRIBUTE ::=
                        {UnformattedPostalAddress IDENTIFIED BY 16}

UnformattedPostalAddress ::= SET {
   printable-address SEQUENCE SIZE (1..ub-pds-physical-address-lines) OF
           PrintableString (SIZE (1..ub-pds-parameter-length)) OPTIONAL,
   teletex-string TeletexString (SIZE
                         (1..ub-unformatted-address-length)) OPTIONAL }

street-address EXTENSION-ATTRIBUTE ::=
                {StreetAddress IDENTIFIED BY 17}

StreetAddress ::= PDSParameter

post-office-box-address EXTENSION-ATTRIBUTE ::=
                {PostOfficeBoxAddress IDENTIFIED BY 18}

PostOfficeBoxAddress ::= PDSParameter

poste-restante-address EXTENSION-ATTRIBUTE ::=
                {PosteRestanteAddress IDENTIFIED BY 19}

PosteRestanteAddress ::= PDSParameter

unique-postal-name EXTENSION-ATTRIBUTE ::=
                {UniquePostalName IDENTIFIED BY 20}



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RFC 2459        Internet X.509 Public Key Infrastructure    January 1999


UniquePostalName ::= PDSParameter

local-postal-attributes EXTENSION-ATTRIBUTE ::=
                {LocalPostalAttributes IDENTIFIED BY 21}

LocalPostalAttributes ::= PDSParameter

PDSParameter ::= SET {
   printable-string PrintableString
            (SIZE(1..ub-pds-parameter-length)) OPTIONAL,
   teletex-string TeletexString
            (SIZE(1..ub-pds-parameter-length)) OPTIONAL }

extended-network-address EXTENSION-ATTRIBUTE ::=
                {ExtendedNetworkAddress IDENTIFIED BY 22}

ExtendedNetworkAddress ::= CHOICE {
        e163-4-address SEQUENCE {
                number [0] NumericString
                   (SIZE (1..ub-e163-4-number-length)),
                sub-address [1] NumericString
                   (SIZE (1..ub-e163-4-sub-address-length)) OPTIONAL},
        psap-address [0] PresentationAddress }

PresentationAddress ::= SEQUENCE {
        pSelector       [0] EXPLICIT OCTET STRING OPTIONAL,
        sSelector       [1] EXPLICIT OCTET STRING OPTIONAL,
        tSelector       [2] EXPLICIT OCTET STRING OPTIONAL,
        nAddresses      [3] EXPLICIT SET SIZE (1..MAX) OF OCTET STRING}


terminal-type EXTENSION-ATTRIBUTE ::= {TerminalType IDENTIFIED BY 23}

TerminalType ::= INTEGER {
   telex (3),
   teletex (4),
   g3-facsimile (5),
   g4-facsimile (6),
   ia5-terminal (7),
   videotex (8) } (0..ub-integer-options)

--      Extension Domain-defined Attributes

teletex-domain-defined-attributes EXTENSION-ATTRIBUTE ::=
   {TeletexDomainDefinedAttributes IDENTIFIED BY 6}

TeletexDomainDefinedAttributes ::= SEQUENCE SIZE
   (1..ub-domain-defined-attributes) OF TeletexDomainDefinedAttribute



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RFC 2459        Internet X.509 Public Key Infrastructure    January 1999


TeletexDomainDefinedAttribute ::= SEQUENCE {
    type TeletexString
         (SIZE (1..ub-domain-defined-attribute-type-length)),
    value TeletexString
         (SIZE (1..ub-domain-defined-attribute-value-length)) }

--  specifications of Upper Bounds
--  shall be regarded as mandatory
--  from Annex B of ITU-T X.411
--  Reference Definition of MTS Parameter Upper Bounds

--      Upper Bounds
ub-name INTEGER ::=     32768
ub-common-name  INTEGER ::=     64
ub-locality-name        INTEGER ::=     128
ub-state-name   INTEGER ::=     128
ub-organization-name    INTEGER ::=     64
ub-organizational-unit-name     INTEGER ::=     64
ub-title        INTEGER ::=     64
ub-match        INTEGER ::=     128

ub-emailaddress-length INTEGER ::= 128

ub-common-name-length INTEGER ::= 64
ub-country-name-alpha-length INTEGER ::= 2
ub-country-name-numeric-length INTEGER ::= 3
ub-domain-defined-attributes INTEGER ::= 4
ub-domain-defined-attribute-type-length INTEGER ::= 8
ub-domain-defined-attribute-value-length INTEGER ::= 128
ub-domain-name-length INTEGER ::= 16
ub-extension-attributes INTEGER ::= 256
ub-e163-4-number-length INTEGER ::= 15
ub-e163-4-sub-address-length INTEGER ::= 40
ub-generation-qualifier-length INTEGER ::= 3
ub-given-name-length INTEGER ::= 16
ub-initials-length INTEGER ::= 5
ub-integer-options INTEGER ::= 256
ub-numeric-user-id-length INTEGER ::= 32
ub-organization-name-length INTEGER ::= 64
ub-organizational-unit-name-length INTEGER ::= 32
ub-organizational-units INTEGER ::= 4
ub-pds-name-length INTEGER ::= 16
ub-pds-parameter-length INTEGER ::= 30
ub-pds-physical-address-lines INTEGER ::= 6
ub-postal-code-length INTEGER ::= 16
ub-surname-length INTEGER ::= 40
ub-terminal-id-length INTEGER ::= 24
ub-unformatted-address-length INTEGER ::= 180



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RFC 2459        Internet X.509 Public Key Infrastructure    January 1999


ub-x121-address-length INTEGER ::= 16

-- Note - upper bounds on TeletexString are measured in characters.
-- A significantly greater number of octets will be required to hold
-- such a value.  As a minimum, 16 octets, or twice the specified upper
-- bound, whichever is the larger, should be allowed.

END











































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RFC 2459        Internet X.509 Public Key Infrastructure    January 1999


B.2 Implicitly Tagged Module, 1993 Syntax


PKIX1Implicit93  {iso(1) identified-organization(3) dod(6) internet(1)
   security(5) mechanisms(5) pkix(7) id-mod(0) id-pkix1-implicit-93(4)}

DEFINITIONS IMPLICIT TAGS::=

BEGIN

--EXPORTS ALL --

IMPORTS
        id-pe, id-qt, id-kp, id-ad, id-qt-unotice,
                ORAddress, Name, RelativeDistinguishedName,
                CertificateSerialNumber, CertificateList,
                AlgorithmIdentifier, ub-name, DirectoryString,
                Attribute, EXTENSION
                FROM PKIX1Explicit93 {iso(1) identified-organization(3)
                dod(6) internet(1) security(5) mechanisms(5) pkix(7)
                id-mod(0) id-pkix1-explicit-93(3)};

-- Key and policy information extensions --

authorityKeyIdentifier EXTENSION ::= {
        SYNTAX          AuthorityKeyIdentifier
        IDENTIFIED BY   id-ce-authorityKeyIdentifier }

AuthorityKeyIdentifier ::= SEQUENCE {
    keyIdentifier               [0] KeyIdentifier            OPTIONAL,
    authorityCertIssuer         [1] GeneralNames             OPTIONAL,
    authorityCertSerialNumber   [2] CertificateSerialNumber  OPTIONAL }
        ( WITH COMPONENTS       {..., authorityCertIssuer PRESENT,
                                authorityCertSerialNumber PRESENT} |
         WITH COMPONENTS        {..., authorityCertIssuer ABSENT,
                                authorityCertSerialNumber ABSENT} )

KeyIdentifier ::= OCTET STRING

subjectKeyIdentifier EXTENSION ::= {
        SYNTAX          SubjectKeyIdentifier
        IDENTIFIED BY   id-ce-subjectKeyIdentifier }

SubjectKeyIdentifier ::= KeyIdentifier

keyUsage EXTENSION ::= {
        SYNTAX  KeyUsage
        IDENTIFIED BY id-ce-keyUsage }



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RFC 2459        Internet X.509 Public Key Infrastructure    January 1999


KeyUsage ::= BIT STRING {
        digitalSignature     (0),
        nonRepudiation       (1),
        keyEncipherment      (2),
        dataEncipherment     (3),
        keyAgreement         (4),
        keyCertSign          (5),
        cRLSign              (6),
      encipherOnly         (7),
      decipherOnly         (8) }

extendedKeyUsage EXTENSION ::= {
        SYNTAX SEQUENCE SIZE (1..MAX) OF KeyPurposeId
        IDENTIFIED BY id-ce-extKeyUsage }

KeyPurposeId ::= OBJECT IDENTIFIER

-- PKIX-defined extended key purpose OIDs
id-kp-serverAuth      OBJECT IDENTIFIER ::= { id-kp 1 }
id-kp-clientAuth      OBJECT IDENTIFIER ::= { id-kp 2 }
id-kp-codeSigning     OBJECT IDENTIFIER ::= { id-kp 3 }
id-kp-emailProtection OBJECT IDENTIFIER ::= { id-kp 4 }
id-kp-ipsecEndSystem  OBJECT IDENTIFIER ::= { id-kp 5 }
id-kp-ipsecTunnel     OBJECT IDENTIFIER ::= { id-kp 6 }
id-kp-ipsecUser       OBJECT IDENTIFIER ::= { id-kp 7 }
id-kp-timeStamping    OBJECT IDENTIFIER ::= { id-kp 8 }

privateKeyUsagePeriod EXTENSION ::= {
        SYNTAX  PrivateKeyUsagePeriod
        IDENTIFIED BY { id-ce-privateKeyUsagePeriod } }

PrivateKeyUsagePeriod ::= SEQUENCE {
        notBefore       [0]     GeneralizedTime OPTIONAL,
        notAfter        [1]     GeneralizedTime OPTIONAL }
        ( WITH COMPONENTS       {..., notBefore PRESENT} |
        WITH COMPONENTS         {..., notAfter PRESENT} )

certificatePolicies EXTENSION ::= {
        SYNTAX  CertificatePoliciesSyntax
        IDENTIFIED BY id-ce-certificatePolicies }

CertificatePoliciesSyntax ::=
                SEQUENCE SIZE (1..MAX) OF PolicyInformation

PolicyInformation ::= SEQUENCE {
        policyIdentifier   CertPolicyId,
        policyQualifiers   SEQUENCE SIZE (1..MAX) OF
                PolicyQualifierInfo OPTIONAL }



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RFC 2459        Internet X.509 Public Key Infrastructure    January 1999


CertPolicyId ::= OBJECT IDENTIFIER

PolicyQualifierInfo ::= SEQUENCE {
        policyQualifierId       CERT-POLICY-QUALIFIER.&id
                                    ({SupportedPolicyQualifiers}),
        qualifier               CERT-POLICY-QUALIFIER.&Qualifier
                                    ({SupportedPolicyQualifiers}
                                    {@policyQualifierId})OPTIONAL }

SupportedPolicyQualifiers CERT-POLICY-QUALIFIER ::= { noticeToUser |
                                                      pointerToCPS }

CERT-POLICY-QUALIFIER ::= CLASS {
        &id             OBJECT IDENTIFIER UNIQUE,
        &Qualifier      OPTIONAL }
WITH SYNTAX {
        POLICY-QUALIFIER-ID     &id
        [QUALIFIER-TYPE &Qualifier] }

policyMappings EXTENSION ::= {
        SYNTAX  PolicyMappingsSyntax
        IDENTIFIED BY id-ce-policyMappings }

PolicyMappingsSyntax ::= SEQUENCE SIZE (1..MAX) OF SEQUENCE {
        issuerDomainPolicy           CertPolicyId,
        subjectDomainPolicy          CertPolicyId }

-- Certificate subject and certificate issuer attributes extensions --

subjectAltName EXTENSION ::= {
        SYNTAX  GeneralNames
        IDENTIFIED BY id-ce-subjectAltName }

GeneralNames ::= SEQUENCE SIZE (1..MAX) OF GeneralName

GeneralName ::= CHOICE {
        otherName                   [0] INSTANCE OF OTHER-NAME,
        rfc822Name                  [1] IA5String,
        dNSName                     [2] IA5String,
        x400Address                 [3] ORAddress,
        directoryName               [4] Name,
        ediPartyName                [5] EDIPartyName,
        uniformResourceIdentifier   [6] IA5String,
        iPAddress                   [7] OCTET STRING,
        registeredID                [8] OBJECT IDENTIFIER }

OTHER-NAME ::= TYPE-IDENTIFIER




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RFC 2459        Internet X.509 Public Key Infrastructure    January 1999


EDIPartyName ::= SEQUENCE {
        nameAssigner        [0] DirectoryString {ub-name} OPTIONAL,
        partyName           [1] DirectoryString {ub-name} }

issuerAltName EXTENSION ::= {
        SYNTAX  GeneralNames
        IDENTIFIED BY id-ce-issuerAltName }

subjectDirectoryAttributes EXTENSION ::= {
        SYNTAX  AttributesSyntax
        IDENTIFIED BY id-ce-subjectDirectoryAttributes }

AttributesSyntax ::= SEQUENCE SIZE (1..MAX) OF Attribute

-- Certification path constraints extensions --

basicConstraints EXTENSION ::= {
        SYNTAX  BasicConstraintsSyntax
        IDENTIFIED BY id-ce-basicConstraints }

BasicConstraintsSyntax ::= SEQUENCE {
        cA                      BOOLEAN DEFAULT FALSE,
        pathLenConstraint       INTEGER (0..MAX) OPTIONAL }

nameConstraints EXTENSION ::= {
        SYNTAX  NameConstraintsSyntax
        IDENTIFIED BY id-ce-nameConstraints }

NameConstraintsSyntax ::= SEQUENCE {
        permittedSubtrees       [0]     GeneralSubtrees OPTIONAL,
        excludedSubtrees        [1]     GeneralSubtrees OPTIONAL }

GeneralSubtrees ::= SEQUENCE SIZE (1..MAX) OF GeneralSubtree

GeneralSubtree ::= SEQUENCE {
        base                    GeneralName,
        minimum         [0]     BaseDistance DEFAULT 0,
        maximum         [1]     BaseDistance OPTIONAL }

BaseDistance ::= INTEGER (0..MAX)

policyConstraints EXTENSION ::= {
        SYNTAX  PolicyConstraintsSyntax
        IDENTIFIED BY id-ce-policyConstraints }

PolicyConstraintsSyntax ::= SEQUENCE {
        requireExplicitPolicy   [0] SkipCerts OPTIONAL,
        inhibitPolicyMapping    [1] SkipCerts OPTIONAL }



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RFC 2459        Internet X.509 Public Key Infrastructure    January 1999


SkipCerts ::= INTEGER (0..MAX)

-- Basic CRL extensions --

cRLNumber EXTENSION ::= {
        SYNTAX  CRLNumber
        IDENTIFIED BY id-ce-cRLNumber }

CRLNumber ::= INTEGER (0..MAX)

reasonCode EXTENSION ::= {
        SYNTAX  CRLReason
        IDENTIFIED BY id-ce-reasonCode }

CRLReason ::= ENUMERATED {
        unspecified             (0),
        keyCompromise           (1),
        cACompromise            (2),
        affiliationChanged      (3),
        superseded              (4),
        cessationOfOperation    (5),
        certificateHold         (6),
        removeFromCRL           (8) }

instructionCode EXTENSION ::= {
        SYNTAX  HoldInstruction
        IDENTIFIED BY id-ce-instructionCode }

HoldInstruction ::= OBJECT IDENTIFIER

-- holdinstructions described in this specification, from ANSI x9

-- ANSI x9 arc holdinstruction arc
holdInstruction OBJECT IDENTIFIER ::= {
     joint-iso-ccitt(2) member-body(2) us(840) x9cm(10040) 2}

-- ANSI X9 holdinstructions referenced by this standard
id-holdinstruction-none OBJECT IDENTIFIER ::= {holdInstruction 1}
id-holdinstruction-callissuer OBJECT IDENTIFIER ::= {holdInstruction 2}
id-holdinstruction-reject OBJECT IDENTIFIER ::= {holdInstruction 3}

invalidityDate EXTENSION ::= {
        SYNTAX  GeneralizedTime
        IDENTIFIED BY id-ce-invalidityDate }

-- CRL distribution points and delta-CRL extensions --

cRLDistributionPoints EXTENSION ::= {



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RFC 2459        Internet X.509 Public Key Infrastructure    January 1999


        SYNTAX  CRLDistPointsSyntax
        IDENTIFIED BY id-ce-cRLDistributionPoints }

CRLDistPointsSyntax ::= SEQUENCE SIZE (1..MAX) OF DistributionPoint

DistributionPoint ::= SEQUENCE {
        distributionPoint       [0]     DistributionPointName OPTIONAL,
        reasons         [1]     ReasonFlags OPTIONAL,
        cRLIssuer               [2]     GeneralNames OPTIONAL }

DistributionPointName ::= CHOICE {
        fullName                [0]     GeneralNames,
        nameRelativeToCRLIssuer [1]     RelativeDistinguishedName }

ReasonFlags ::= BIT STRING {
        unused                  (0),
        keyCompromise           (1),
        caCompromise            (2),
        affiliationChanged      (3),
        superseded              (4),
        cessationOfOperation    (5),
        certificateHold         (6) }

issuingDistributionPoint EXTENSION ::= {
        SYNTAX  IssuingDistPointSyntax
        IDENTIFIED BY id-ce-issuingDistributionPoint }

IssuingDistPointSyntax ::= SEQUENCE {
        distributionPoint       [0] DistributionPointName OPTIONAL,
        onlyContainsUserCerts   [1] BOOLEAN DEFAULT FALSE,
        onlyContainsCACerts     [2] BOOLEAN DEFAULT FALSE,
        onlySomeReasons         [3] ReasonFlags OPTIONAL,
        indirectCRL             [4] BOOLEAN DEFAULT FALSE }

certificateIssuer EXTENSION ::= {
        SYNTAX          GeneralNames
        IDENTIFIED BY id-ce-certificateIssuer }

deltaCRLIndicator EXTENSION ::= {
        SYNTAX          BaseCRLNumber
        IDENTIFIED BY id-ce-deltaCRLIndicator }

BaseCRLNumber ::= CRLNumber

-- Object identifier assignments for ISO certificate extensions --
id-ce   OBJECT IDENTIFIER       ::=     {joint-iso-ccitt(2) ds(5) 29}

id-ce-subjectDirectoryAttributes   OBJECT IDENTIFIER ::= {id-ce 9}



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id-ce-subjectKeyIdentifier         OBJECT IDENTIFIER ::= {id-ce 14}
id-ce-keyUsage                     OBJECT IDENTIFIER ::= {id-ce 15}
id-ce-privateKeyUsagePeriod        OBJECT IDENTIFIER ::= {id-ce 16}
id-ce-subjectAltName               OBJECT IDENTIFIER ::= {id-ce 17}
id-ce-issuerAltName                OBJECT IDENTIFIER ::= {id-ce 18}
id-ce-basicConstraints             OBJECT IDENTIFIER ::= {id-ce 19}
id-ce-cRLNumber                    OBJECT IDENTIFIER ::= {id-ce 20}
id-ce-reasonCode                   OBJECT IDENTIFIER ::= {id-ce 21}
id-ce-instructionCode              OBJECT IDENTIFIER ::= {id-ce 23}
id-ce-invalidityDate               OBJECT IDENTIFIER ::= {id-ce 24}
id-ce-deltaCRLIndicator            OBJECT IDENTIFIER ::= {id-ce 27}
id-ce-issuingDistributionPoint     OBJECT IDENTIFIER ::= {id-ce 28}
id-ce-certificateIssuer            OBJECT IDENTIFIER ::= {id-ce 29}
id-ce-nameConstraints              OBJECT IDENTIFIER ::= {id-ce 30}
id-ce-cRLDistributionPoints        OBJECT IDENTIFIER ::= {id-ce 31}
id-ce-certificatePolicies          OBJECT IDENTIFIER ::= {id-ce 32}
id-ce-policyMappings               OBJECT IDENTIFIER ::= {id-ce 33}
id-ce-policyConstraints            OBJECT IDENTIFIER ::= {id-ce 36}
id-ce-authorityKeyIdentifier       OBJECT IDENTIFIER ::= {id-ce 35}
id-ce-extKeyUsage                  OBJECT IDENTIFIER ::= {id-ce 37}

-- PKIX 1 extensions

authorityInfoAccess EXTENSION ::= {
        SYNTAX  AuthorityInfoAccessSyntax
        IDENTIFIED BY id-pe-authorityInfoAccess }

AuthorityInfoAccessSyntax  ::=
        SEQUENCE SIZE (1..MAX) OF AccessDescription

AccessDescription  ::=  SEQUENCE {
        accessMethod          OBJECT IDENTIFIER,
        accessLocation        GeneralName  }

id-pe-authorityInfoAccess OBJECT IDENTIFIER ::= { id-pe 1 }

id-ad-ocsp      OBJECT IDENTIFIER ::= { id-ad 1 }
id-ad-caIssuers OBJECT IDENTIFIER ::= { id-ad 2 }

-- PKIX policy qualifier definitions

noticeToUser CERT-POLICY-QUALIFIER ::= {
     POLICY-QUALIFIER-ID    id-qt-cps QUALIFIER-TYPE       CPSuri}

pointerToCPS CERT-POLICY-QUALIFIER ::= {
     POLICY-QUALIFIER-ID    id-qt-unotice QUALIFIER-TYPE   UserNotice}

id-qt-cps      OBJECT IDENTIFIER ::=  { id-qt 1 }



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id-qt-unotice  OBJECT IDENTIFIER ::=  { id-qt 2 }

CPSuri ::= IA5String

UserNotice ::= SEQUENCE {
     noticeRef        NoticeReference OPTIONAL,
     explicitText     DisplayText OPTIONAL}

NoticeReference ::= SEQUENCE {
     organization     DisplayText,
     noticeNumbers    SEQUENCE OF INTEGER }

DisplayText ::= CHOICE {
     visibleString    VisibleString  (SIZE (1..200)),
     bmpString        BMPString      (SIZE (1..200)),
     utf8String       UTF8String     (SIZE (1..200)) }


END
































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Appendix C. ASN.1 Notes

   The construct "SEQUENCE SIZE (1..MAX) OF" appears in several ASN.1
   constructs. A valid ASN.1 sequence will have zero or more entries.
   The SIZE (1..MAX) construct constrains the sequence to have at least
   one entry. MAX indicates the upper bound is unspecified.
   Implementations are free to choose an upper bound that suits their
   environment.

   The construct "positiveInt ::= INTEGER (0..MAX)" defines positiveInt
   as a subtype of INTEGER containing integers greater than or equal to
   zero.  The upper bound is unspecified. Implementations are free to
   select an upper bound that suits their environment.

   The character string type PrintableString supports a very basic Latin
   character set:  the lower case letters 'a' through 'z', upper case
   letters 'A' through 'Z', the digits '0' through '9', eleven special
   characters ' " ( ) + , - . / : ? and space.

   The character string type TeletexString is a superset of
   PrintableString.  TeletexString supports a fairly standard (ascii-
   like) Latin character set, Latin characters with non-spacing accents
   and Japanese characters.

   The character string type UniversalString supports any of the
   characters allowed by ISO 10646-1. ISO 10646 is the Universal
   multiple-octet coded Character Set (UCS).  ISO 10646-1 specifes the
   architecture and the "basic multilingual plane" - a large standard
   character set which includes all major world character standards.

   The character string type UTF8String will be introduced in the 1998
   version of ASN.1.  UTF8String is a universal type and has been
   assigned tag number 12.  The content of UTF8String was defined by RFC
   2044 and updated in RFC 2279, "UTF-8, a transformation Format of ISP
   10646."  ISO is expected to formally add UTF8String to the list of
   choices for DirectoryString in 1998 as well.

   In anticipation of these changes, and in conformance with IETF Best
   Practices codified in RFC 2277, IETF Policy on Character Sets and
   Languages, this document includes UTF8String as a choice in
   DirectoryString and the CPS qualifier extensions.










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Appendix D. Examples

   This section contains four examples: three certificates and a CRL.
   The first two certificates and the CRL comprise a minimal
   certification path.

   Section D.1 contains an annotated hex dump of a "self-signed"
   certificate issued by a CA whose distinguished name is
   cn=us,o=gov,ou=nist.  The certificate contains a DSA public key with
   parameters, and is signed by the corresponding DSA private key.

   Section D.2 contains an annotated hex dump of an end-entity
   certificate.  The end entity certificate contains a DSA public key,
   and is signed by the private key corresponding to the "self-signed"
   certificate in section D.1.

   Section D.3 contains a dump of an end entity certificate which
   contains an RSA public key and is signed with RSA and MD5.  This
   certificate is not part of the minimal certification path.

   Section D.4 contains an annotated hex dump of a CRL.  The CRL is
   issued by the CA whose distinguished name is cn=us,o=gov,ou=nist and
   the list of revoked certificates includes the end entity certificate
   presented in D.2.

D.1 Certificate

   This section contains an annotated hex dump of a 699 byte version 3
   certificate.  The certificate contains the following information:
   (a) the serial number is 17 (11 hex);
   (b) the certificate is signed with DSA and the SHA-1 hash algorithm;
   (c) the issuer's distinguished name is OU=nist; O=gov; C=US
   (d) and the subject's distinguished name is OU=nist; O=gov; C=US
   (e) the certificate was issued on June 30, 1997 and will expire on
   December 31, 1997;
   (f) the certificate contains a 1024 bit DSA public key with
   parameters;
   (g) the certificate contains a subject key identifier extension; and
   (h) the certificate is a CA certificate (as indicated through the
   basic constraints extension.)

0000 30 82 02 b7  695: SEQUENCE
0004 30 82 02 77  631: . SEQUENCE    tbscertificate
0008 a0 03          3: . . [0]
0010 02 01          1: . . . INTEGER 2
                     : 02
0013 02 01          1: . . INTEGER 17
                     : 11



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0016 30 09          9: . . SEQUENCE
0018 06 07          7: . . . OID 1.2.840.10040.4.3: dsa-with-sha
                     : 2a 86 48 ce 38 04 03
0027 30 2a         42: . . SEQUENCE
0029 31 0b         11: . . . SET
0031 30 09          9: . . . . SEQUENCE
0033 06 03          3: . . . . . OID 2.5.4.6: C
                     : 55 04 06
0038 13 02          2: . . . . . PrintableString  'US'
                     : 55 53
0042 31 0c         12: . . . SET
0044 30 0a         10: . . . . SEQUENCE
0046 06 03          3: . . . . . OID 2.5.4.10: O
                     : 55 04 0a
0051 13 03          3: . . . . . PrintableString  'gov'
                     : 67 6f 76
0056 31 0d         13: . . . SET
0058 30 0b         11: . . . . SEQUENCE
0060 06 03          3: . . . . . OID 2.5.4.11: OU
                     : 55 04 0b
0065 13 04          4: . . . . . PrintableString  'nist'
                     : 6e 69 73 74
0071 30 1e         30: . . SEQUENCE
0073 17 0d         13: . . . UTCTime  '970630000000Z'
                     : 39 37 30 36 33 30 30 30 30 30 30 30 5a
0088 17 0d         13: . . . UTCTime  '971231000000Z'
                     : 39 37 31 32 33 31 30 30 30 30 30 30 5a
0103 30 2a         42: . . SEQUENCE
0105 31 0b         11: . . . SET
0107 30 09          9: . . . . SEQUENCE
0109 06 03          3: . . . . . OID 2.5.4.6: C
                     : 55 04 06
0114 13 02          2: . . . . . PrintableString  'US'
                     : 55 53
0118 31 0c         12: . . . SET
0120 30 0a         10: . . . . SEQUENCE
0122 06 03          3: . . . . . OID 2.5.4.10: O
                     : 55 04 0a
0127 13 03          3: . . . . . PrintableString  'gov'
                     : 67 6f 76
0132 31 0d         13: . . . SET
0134 30 0b         11: . . . . SEQUENCE
0136 06 03          3: . . . . . OID 2.5.4.11: OU
                     : 55 04 0b
0141 13 04          4: . . . . . PrintableString  'nist'
                     : 6e 69 73 74
0147 30 82 01 b4  436: . . SEQUENCE
0151 30 82 01 29  297: . . . SEQUENCE



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0155 06 07          7: . . . . OID 1.2.840.10040.4.1: dsa
                     : 2a 86 48 ce 38 04 01
0164 30 82 01 1c  284: . . . . SEQUENCE
0168 02 81 80     128: . . . . . INTEGER
                     : d4 38 02 c5 35 7b d5 0b a1 7e 5d 72 59 63 55 d3
                     : 45 56 ea e2 25 1a 6b c5 a4 ab aa 0b d4 62 b4 d2
                     : 21 b1 95 a2 c6 01 c9 c3 fa 01 6f 79 86 83 3d 03
                     : 61 e1 f1 92 ac bc 03 4e 89 a3 c9 53 4a f7 e2 a6
                     : 48 cf 42 1e 21 b1 5c 2b 3a 7f ba be 6b 5a f7 0a
                     : 26 d8 8e 1b eb ec bf 1e 5a 3f 45 c0 bd 31 23 be
                     : 69 71 a7 c2 90 fe a5 d6 80 b5 24 dc 44 9c eb 4d
                     : f9 da f0 c8 e8 a2 4c 99 07 5c 8e 35 2b 7d 57 8d
0299 02 14         20: . . . . . INTEGER
                     : a7 83 9b f3 bd 2c 20 07 fc 4c e7 e8 9f f3 39 83
                     : 51 0d dc dd
0321 02 81 80     128: . . . . . INTEGER
                     : 0e 3b 46 31 8a 0a 58 86 40 84 e3 a1 22 0d 88 ca
                     : 90 88 57 64 9f 01 21 e0 15 05 94 24 82 e2 10 90
                     : d9 e1 4e 10 5c e7 54 6b d4 0c 2b 1b 59 0a a0 b5
                     : a1 7d b5 07 e3 65 7c ea 90 d8 8e 30 42 e4 85 bb
                     : ac fa 4e 76 4b 78 0e df 6c e5 a6 e1 bd 59 77 7d
                     : a6 97 59 c5 29 a7 b3 3f 95 3e 9d f1 59 2d f7 42
                     : 87 62 3f f1 b8 6f c7 3d 4b b8 8d 74 c4 ca 44 90
                     : cf 67 db de 14 60 97 4a d1 f7 6d 9e 09 94 c4 0d
0452 03 81 84     132: . . . BIT STRING  (0 unused bits)
                     : 02 81 80 aa 98 ea 13 94 a2 db f1 5b 7f 98 2f 78
                     : e7 d8 e3 b9 71 86 f6 80 2f 40 39 c3 da 3b 4b 13
                     : 46 26 ee 0d 56 c5 a3 3a 39 b7 7d 33 c2 6b 5c 77
                     : 92 f2 55 65 90 39 cd 1a 3c 86 e1 32 eb 25 bc 91
                     : c4 ff 80 4f 36 61 bd cc e2 61 04 e0 7e 60 13 ca
                     : c0 9c dd e0 ea 41 de 33 c1 f1 44 a9 bc 71 de cf
                     : 59 d4 6e da 44 99 3c 21 64 e4 78 54 9d d0 7b ba
                     : 4e f5 18 4d 5e 39 30 bf e0 d1 f6 f4 83 25 4f 14
                     : aa 71 e1
0587 a3 32         50: . . [3]
0589 30 30         48: . . . SEQUENCE
0591 30 0f          9: . . . . SEQUENCE
0593 06 03          3: . . . . . OID 2.5.29.19: basicConstraints
                     : 55 1d 13
0598 01 01          1: . . . . . TRUE
                     : ff
0601 04 05          5: . . . . . OCTET STRING
                     : 30 03 01 01 ff
0608 30 1d         29: . SEQUENCE
0610 06 03          3: . . . . . OID 2.5.29.14: subjectKeyIdentifier
                     : 55 1d 0e
0615 04 16         22: . . . . . OCTET STRING
                     : 04 14 e7 26 c5 54 cd 5b a3 6f 35 68 95 aa d5 ff



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                     : 1c 21 e4 22 75 d6
0639 30 09          9: . SEQUENCE
0641 06 07          7: . . OID 1.2.840.10040.4.3: dsa-with-sha
                     : 2a 86 48 ce 38 04 03
0650 03 2f         47: . BIT STRING  (0 unused bits)
                     : 30 2c 02 14 a0 66 c1 76 33 99 13 51 8d 93 64 2f
                     : ca 13 73 de 79 1a 7d 33 02 14 5d 90 f6 ce 92 4a
                     : bf 29 11 24 80 28 a6 5a 8e 73 b6 76 02 68

D.2 Certificate

   This section contains an annotated hex dump of a 730 byte version 3
   certificate.  The certificate contains the following information:
   (a) the serial number is 18 (12 hex);
   (b) the certificate is signed with DSA and the SHA-1 hash algorithm;
   (c) the issuer's distinguished name is OU=nist; O=gov; C=US
   (d) and the subject's distinguished name is CN=Tim Polk; OU=nist;
   O=gov; C=US
   (e) the certificate was valid from July 30, 1997 through December 1,
   1997;
   (f) the certificate contains a 1024 bit DSA public key;
   (g) the certificate is an end entity certificate, as the basic
   constraints extension is not present;
   (h) the certificate contains an authority key identifier extension;
   and
   (i) the certificate includes one alternative name - an RFC 822
   address.

0000 30 82 02 d6  726: SEQUENCE
0004 30 82 02 96  662: . SEQUENCE
0008 a0 03          3: . . [0]
0010 02 01          1: . . . INTEGER 2
                     : 02
0013 02 01          1: . . INTEGER 18
                     : 12
0016 30 09          9: . . SEQUENCE
0018 06 07          7: . . . OID 1.2.840.10040.4.3: dsa-with-sha
                     : 2a 86 48 ce 38 04 03
0027 30 2a         42: . . SEQUENCE
0029 31 0b         11: . . . SET
0031 30 09          9: . . . . SEQUENCE
0033 06 03          3: . . . . . OID 2.5.4.6: C
                     : 55 04 06
0038 13 02          2: . . . . . PrintableString  'US'
                     : 55 53
0042 31 0c         12: . . . SET
0044 30 0a         10: . . . . SEQUENCE
0046 06 03          3: . . . . . OID 2.5.4.10: O



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                     : 55 04 0a
0051 13 03          3: . . . . . PrintableString  'gov'
                     : 67 6f 76
0056 31 0d         13: . . . SET
0058 30 0b         11: . . . . SEQUENCE
0060 06 03          3: . . . . . OID 2.5.4.11: OU
                     : 55 04 0b
0065 13 04          4: . . . . . PrintableString  'nist'
                     : 6e 69 73 74
0071 30 1e         30: . . SEQUENCE
0073 17 0d         13: . . . UTCTime  '970730000000Z'
                     : 39 37 30 37 33 30 30 30 30 30 30 30 5a
0088 17 0d         13: . . . UTCTime  '971201000000Z'
                     : 39 37 31 32 30 31 30 30 30 30 30 30 5a
0103 30 3d         61: . . SEQUENCE
0105 31 0b         11: . . . SET
0107 30 09          9: . . . . SEQUENCE
0109 06 03          3: . . . . . OID 2.5.4.6: C
                     : 55 04 06
0114 13 02          2: . . . . . PrintableString  'US'
                     : 55 53
0118 31 0c         12: . . . SET
0120 30 0a         10: . . . . SEQUENCE
0122 06 03          3: . . . . . OID 2.5.4.10: O
                     : 55 04 0a
0127 13 03          3: . . . . . PrintableString  'gov'
                     : 67 6f 76
0132 31 0d         13: . . . SET
0134 30 0b         11: . . . . SEQUENCE
0136 06 03          3: . . . . . OID 2.5.4.11: OU
                     : 55 04 0b
0141 13 04          4: . . . . . PrintableString  'nist'
                     : 6e 69 73 74
0147 31 11         17: . . . SET
0149 30 0f         15: . . . . SEQUENCE
0151 06 03          3: . . . . . OID 2.5.4.3: CN
                     : 55 04 03
0156 13 08          8: . . . . . PrintableString  'Tim Polk'
                     : 54 69 6d 20 50 6f 6c 6b
0166 30 82 01 b4  436: . . SEQUENCE
0170 30 82 01 29  297: . . . SEQUENCE
0174 06 07          7: . . . . OID 1.2.840.10040.4.1: dsa
                     : 2a 86 48 ce 38 04 01
0183 30 82 01 1c  284: . . . . SEQUENCE
0187 02 81 80     128: . . . . . INTEGER
                     : d4 38 02 c5 35 7b d5 0b a1 7e 5d 72 59 63 55 d3
                     : 45 56 ea e2 25 1a 6b c5 a4 ab aa 0b d4 62 b4 d2
                     : 21 b1 95 a2 c6 01 c9 c3 fa 01 6f 79 86 83 3d 03



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                     : 61 e1 f1 92 ac bc 03 4e 89 a3 c9 53 4a f7 e2 a6
                     : 48 cf 42 1e 21 b1 5c 2b 3a 7f ba be 6b 5a f7 0a
                     : 26 d8 8e 1b eb ec bf 1e 5a 3f 45 c0 bd 31 23 be
                     : 69 71 a7 c2 90 fe a5 d6 80 b5 24 dc 44 9c eb 4d
                     : f9 da f0 c8 e8 a2 4c 99 07 5c 8e 35 2b 7d 57 8d
0318 02 14         20: . . . . . INTEGER
                     : a7 83 9b f3 bd 2c 20 07 fc 4c e7 e8 9f f3 39 83
                     : 51 0d dc dd
0340 02 81 80     128: . . . . . INTEGER
                     : 0e 3b 46 31 8a 0a 58 86 40 84 e3 a1 22 0d 88 ca
                     : 90 88 57 64 9f 01 21 e0 15 05 94 24 82 e2 10 90
                     : d9 e1 4e 10 5c e7 54 6b d4 0c 2b 1b 59 0a a0 b5
                     : a1 7d b5 07 e3 65 7c ea 90 d8 8e 30 42 e4 85 bb
                     : ac fa 4e 76 4b 78 0e df 6c e5 a6 e1 bd 59 77 7d
                     : a6 97 59 c5 29 a7 b3 3f 95 3e 9d f1 59 2d f7 42
                     : 87 62 3f f1 b8 6f c7 3d 4b b8 8d 74 c4 ca 44 90
                     : cf 67 db de 14 60 97 4a d1 f7 6d 9e 09 94 c4 0d
0471 03 81 84     132: . . . BIT STRING  (0 unused bits)
                     : 02 81 80 a8 63 b1 60 70 94 7e 0b 86 08 93 0c 0d
                     : 08 12 4a 58 a9 af 9a 09 38 54 3b 46 82 fb 85 0d
                     : 18 8b 2a 77 f7 58 e8 f0 1d d2 18 df fe e7 e9 35
                     : c8 a6 1a db 8d 3d 3d f8 73 14 a9 0b 39 c7 95 f6
                     : 52 7d 2d 13 8c ae 03 29 3c 4e 8c b0 26 18 b6 d8
                     : 11 1f d4 12 0c 13 ce 3f f1 c7 05 4e df e1 fc 44
                     : fd 25 34 19 4a 81 0d dd 98 42 ac d3 b6 91 0c 7f
                     : 16 72 a3 a0 8a d7 01 7f fb 9c 93 e8 99 92 c8 42
                     : 47 c6 43
0606 a3 3e         62: . . [3]
0608 30 3c         60: . . . SEQUENCE
0610 30 19         25: . . . . SEQUENCE
0612 06 03          3: . . . . . OID 2.5.29.17: subjectAltName
                     : 55 1d 11
0617 04 12         18: . . . . . OCTET STRING
                     : 30 10 81 0e 77 70 6f 6c 6b 40 6e 69 73 74 2e 67
                     : 6f 76
0637 30 1f         31: . . . . SEQUENCE
0639 06 03          3: . . . . . OID 2.5.29.35: subjectAltName
                     : 55 1d 23
0644 04 18         24: . . . . . OCTET STRING
                     : 30 16 80 14 e7 26 c5 54 cd 5b a3 6f 35 68 95 aa
                     : d5 ff 1c 21 e4 22 75 d6
0670 30 09          9: . SEQUENCE
0672 06 07          7: . . OID 1.2.840.10040.4.3: dsa-with-sha
                     : 2a 86 48 ce 38 04 03
0681 03 2f         47: . BIT STRING  (0 unused bits)
                     : 30 2c 02 14 3c 02 e0 ab d9 5d 05 77 75 15 71 58
                     : 92 29 48 c4 1c 54 df fc 02 14 5b da 53 98 7f c5
                     : 33 df c6 09 b2 7a e3 6f 97 70 1e 14 ed 94



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D.3 End-Entity Certificate Using RSA

   This section contains an annotated hex dump of a 675 byte version 3
   certificate.  The certificate contains the following information:
   (a) the serial number is 256;
   (b) the certificate is signed with RSA and the MD2 hash algorithm;
   (c) the issuer's distinguished name is OU=Dept. Arquitectura de
   Computadors; O=Universitat Politecnica de Catalunya; C=ES
   (d) and the subject's distinguished name is CN=Francisco Jordan;
   OU=Dept. Arquitectura de Computadors; O=Universitat Politecnica de
   Catalunya; C=ES
   (e) the certificate was issued on May 21, 1996 and expired on May 21,
   1997;
   (f) the certificate contains a 768 bit RSA public key;
   (g) the certificate is an end entity certificate (not a CA
   certificate);
   (h) the certificate includes an alternative subject name and an
   alternative issuer name - bothe are URLs;
   (i) the certificate include an authority key identifier and
   certificate policies extensions; and
   (j) the certificate includes a critical key usage extension
   specifying the public is intended for generation of digital
   signatures.

0000 30 80           : SEQUENCE   (size undefined)
0002 30 82 02 40  576: . SEQUENCE
0006 a0 03          3: . . [0]
0008 02 01          1: . . . INTEGER 2
                     : 02
0011 02 02          2: . . INTEGER 256
                     : 01 00
0015 30 0d         13: . . SEQUENCE
0017 06 09          9: . . . OID 1.2.840.113549.1.1.2:
                                       MD2WithRSAEncryption
                     : 2a 86 48 86 f7 0d 01 01 02
0028 05 00          0: . . . NULL
0030 30 68         88: . . SEQUENCE
0032 31 0b         11: . . . SET
0034 30 09          9: . . . . SEQUENCE
0036 06 03          3: . . . . . OID 2.5.4.6: C
                     : 55 04 06
0041 13 02          2: . . . . . PrintableString  'ES'
                     : 45 53
0045 31 2d         45: . . . SET
0047 30 2b         43: . . . . SEQUENCE
0049 06 03          3: . . . . . OID 2.5.4.10: O
                     : 55 04 0a
0054 13 24         36: . . . . . PrintableString



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                     'Universitat Politecnica de Catalunya'
                     : 55 6e 69 76 65 72 73 69 74 61 74 20 50 6f 6c 69
                     : 74 65 63 6e 69 63 61 20 64 65 20 43 61 74 61 6c
                     : 75 6e 79 61
0092 31 2a         42: . . . SET
0094 30 28         40: . . . . SEQUENCE
0096 06 03          3: . . . . . OID 2.5.4.11: OU
                     : 55 04 0b
0101 13 21         33: . . . . . PrintableString
                     'OU=Dept. Arquitectura de Computadors'
                     : 44 65 70 74 2e 20 41 72 71 75 69 74 65 63 74 75
                     : 72 61 20 64 65 20 43 6f 6d 70 75 74 61 64 6f 72
                     : 73
0136 30 1e         30: . . SEQUENCE
0138 17 0d         13: . . . UTCTime  '960521095826Z'
                     : 39 36 30 37 32 32 31 37 33 38 30 32 5a
0153 17 0d         13: . . . UTCTime  '979521095826Z'
                     : 39 37 30 37 32 32 31 37 33 38 30 32 5a
0168 30 81 83     112: . . SEQUENCE
0171 31 0b         11: . . . SET
0173 30 09          9: . . . . SEQUENCE
0175 06 03          3: . . . . . OID 2.5.4.6: C
                     : 55 04 06
0180 13 02          2: . . . . . PrintableString  'ES'
                     : 45 53
0184 31 2d         12: . . . SET
0186 30 2b         16: . . . . SEQUENCE
0188 06 03          3: . . . . . OID 2.5.4.10: O
                     : 55 04 0a
0193 13 24         36: . . . . . PrintableString
                     'Universitat Politecnica de Catalunya'
                     : 55 6e 69 76 65 72 73 69 74 61 74 20 50 6f 6c 69
                     : 74 65 63 6e 69 63 61 20 64 65 20 43 61 74 61 6c
                     : 75 6e 79 61
0231 31 2a         42: . . . SET
0233 30 28         40: . . . . SEQUENCE
0235 06 03          3: . . . . . OID 2.5.4.11: OU
                     : 55 04 0b
0240 13 21         33: . . . . . PrintableString
                     'Dept. Arquitectura de Computadors'
                     : 44 65 70 74 2e 20 41 72 71 75 69 74 65 63 74 75
                     : 72 61 20 64 65 20 43 6f 6d 70 75 74 61 64 6f 72
                     : 73
0275 31 19         22: . . . SET
0277 30 17         20: . . . . SEQUENCE
0279 06 03          3: . . . . . OID 2.5.4.3: CN
                     : 55 04 03
0284 13 10         16: . . . . . PrintableString 'Francisco Jordan'



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                     : 46 72 61 6e 63 69 73 63 6f 20 4a 6f 72 64 61 6e
0302 30 7c          2: . . SEQUENCE
0304 30 0d         13: . . . SEQUENCE
0306 06 09          9: . . . . OID 1.2.840.113549.1.1.1: RSAEncryption
                     : 2a 86 48 86 f7 0d 01 01 01
0317 05 00          0: . . . . NULL
0319 03 6b        107: . . . BIT STRING
                     : 00   (0 unused bits)
                     : 30 68 02 61 00 be aa 8b 77 54 a3 af ca 77 9f 2f
                     : b0 cf 43 88 ff a6 6d 79 55 5b 61 8c 68 ec 48 1e
                     : 8a 86 38 a4 fe 19 b8 62 17 1d 9d 0f 47 2c ff 63
                     : 8f 29 91 04 d1 52 bc 7f 67 b6 b2 8f 74 55 c1 33
                     : 21 6c 8f ab 01 95 24 c8 b2 73 93 9d 22 61 50 a9
                     : 35 fb 9d 57 50 32 ef 56 52 50 93 ab b1 88 94 78
                     : 56 15 c6 1c 8b 02 03 01 00 01
0428 a3 81 97     151: . . [3]
0431 30 3c         60: . . . SEQUENCE
0433 30 1f         31: . . . . SEQUENCE
0435 06 03          3: . . . . . OID 2.5.29.35: authorityKeyIdentifier
                     : 55 1d 23
0440 04 14         22: . . . . . OCTET STRING
                     : 30 12 80 10 0e 6b 3a bf 04 ea 04 c3 0e 6b 3a bf
                     : 04 ea 04 c3
0464 30 19         25: . . . . SEQUENCE
0466 06 03          3: . . . . . OID 2.5.29.15: keyUsage
                     : 55 1d 0f
0471 01 01          1: . . . . . TRUE
0474 04 04          4: . . . . . OCTET STRING
                     : 03 02 07 80
0480 30 19         25: . . . . SEQUENCE
0482 06 03          3: . . . . . OID 2.5.29.32: certificatePolicies
                     : 55 1d 20
0487 04 21         33: . . . . . OCTET STRING
                     : 30 1f 30 1d 06 04 2a 84 80 00 30 15 30 07 06 05
                     : 2a 84 80 00 01 30 0a 06 05 2a 84 80 00 02 02 01
                     : 0a
0522 30 1c         28: . . . . SEQUENCE
0524 06 03          3: . . . . . OID 2.5.29.17: subjectAltName
                     : 55 1d 11
0529 04 15         21: . . . . . OCTET STRING
                     : 30 13 86 11 68 74 74 70 3a 2f 2f 61 63 2e 75 70
                     : 63 2e 65 73 2f
0552 30 19         25: . . . . SEQUENCE
0554 06 03          3: . . . . . OID 2.5.29.18: issuerAltName
                     : 55 1d 12
0559 04 12         18: . . . . . OCTET STRING
                     : 30 14 86 12 68 74 74 70 3a 2f 2f 77 77 77 2e 75
                     : 70 63 2e 65



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0579 30 80           : . SEQUENCE (indefinite length)
0581 06 07          7: . . OID
0583 05 00          0: . . NULL
0585 00 00          0: . . end of contents marker
0587 03 81 81      47: . BIT STRING
                     : 00      (0 unused bits)
                     : 5c 01 bd b5 41 88 87 7a 0e d3 0e 6b 3a bf 04 ea
                     : 04 cb 5f 61 72 3c a3 bd 78 f5 66 17 fe 37 3a ab
                     : eb 67 bf b7 da a8 38 f6 33 15 71 75 2f b9 8c 91
                     : a0 e4 87 ba 4b 43 a0 22 8f d3 a9 86 43 89 e6 50
                     : 5c 01 bd b5 41 88 87 7a 0e d3 0e 6b 3a bf 04 ea
                     : 04 cb 5f 61 72 3c a3 bd 78 f5 66 17 fe 37 3a ab
                     : eb 67 bf b7 da a8 38 f6 33 15 71 75 2f b9 8c 91
                     : a0 e4 87 ba 4b 43 a0 22 8f d3 a9 86 43 89 e6 50
0637 00 00          0: . . end of contents marker

D.4 Certificate Revocation List

   This section contains an annotated hex dump of a version 2 CRL with
   one extension (cRLNumber). The CRL was issued by OU=nist;O=gov;C=us
   on July 7, 1996; the next scheduled issuance was August 7, 1996.  The
   CRL includes one revoked certificates: serial number 18 (12 hex).
   The CRL itself is number 18, and it was signed with DSA and SHA-1.

0000 30 81 ba     186: SEQUENCE
0003 30 7c        124: . SEQUENCE
0005 02 01          1: . . INTEGER 1
                     : 01
0008 30 09          9: . . SEQUENCE
0010 06 07          7: . . . OID 1.2.840.10040.4.3: dsa-with-sha
                     : 2a 86 48 ce 38 04 03
0019 30 2a         42: . . SEQUENCE
0021 31 0b         11: . . . SET
0023 30 09          9: . . . . SEQUENCE
0025 06 03          3: . . . . . OID 2.5.4.6: C
                     : 55 04 06
0030 13 02          2: . . . . . PrintableString  'US'
                     : 55 53
0034 31 0c         12: . . . SET
0036 30 0a         10: . . . . SEQUENCE
0038 06 03          3: . . . . . OID 2.5.4.10: O
                     : 55 04 0a
0043 13 03          3: . . . . . PrintableString  'gov'
                     : 67 6f 76
0048 31 0d         13: . . . SET
0050 30 0b         11: . . . . SEQUENCE
0052 06 03          3: . . . . . OID 2.5.4.11: OU
                     : 55 04 0b



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0057 13 04          4: . . . . . PrintableString  'nist'
                     : 6e 69 73 74
0063 17 0d         13: . . UTCTime  '970801000000Z'
                     : 39 37 30 38 30 31 30 30 30 30 30 30 5a
0078 17 0d         13: . . UTCTime  '970808000000Z'
                     : 39 37 30 38 30 38 30 30 30 30 30 30 5a
0093 30 22         34: . . SEQUENCE
0095 30 20         32: . . . SEQUENCE
0097 02 01          1: . . . . INTEGER 18
                     : 12
0100 17 0d         13: . . . . UTCTime  '970731000000Z'
                     : 39 37 30 37 33 31 30 30 30 30 30 30 5a
0115 30 0c         12: . . . . SEQUENCE
0117 30 0a         10: . . . . . SEQUENCE
0119 06 03          3: . . . . . . OID 2.5.29.21: reasonCode
                     : 55 1d 15
0124 04 03          3: . . . . . . OCTET STRING
                     : 0a 01 01
0129 30 09          9: . SEQUENCE
0131 06 07          7: . . OID 1.2.840.10040.4.3: dsa-with-sha
                     : 2a 86 48 ce 38 04 03
0140 03 2f         47: . BIT STRING  (0 unused bits)
                     : 30 2c 02 14 9e d8 6b c1 7d c2 c4 02 f5 17 84 f9
                     : 9f 46 7a ca cf b7 05 8a 02 14 9e 43 39 85 dc ea
                     : 14 13 72 93 54 5d 44 44 e5 05 fe 73 9a b2


























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Appendix E. Authors' Addresses

   Russell Housley
   SPYRUS
   381 Elden Street
   Suite 1120
   Herndon, VA 20170
   USA

   EMail: housley@spyrus.com


   Warwick Ford
   VeriSign, Inc.
   One Alewife Center
   Cambridge, MA 02140
   USA

   EMail: wford@verisign.com


   Tim Polk
   NIST
   Building 820, Room 426
   Gaithersburg, MD 20899
   USA

   EMail: wpolk@nist.gov


   David Solo
   Citicorp
   666 Fifth Ave, 3rd Floor
   New York, NY 10103
   USA

   EMail: david.solo@citicorp.com














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Appendix F.  Full Copyright Statement

   Copyright (C) The Internet Society (1999).  All Rights Reserved.

   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implementation may be prepared, copied, published
   and distributed, in whole or in part, without restriction of any
   kind, provided that the above copyright notice and this paragraph are
   included on all such copies and derivative works.  However, this
   document itself may not be modified in any way, such as by removing
   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of
   developing Internet standards in which case the procedures for
   copyrights defined in the Internet Standards process must be
   followed, or as required to translate it into languages other than
   English.

   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assigns.

   This document and the information contained herein is provided on an
   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
   BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
























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