Package org.bouncycastle.crypto.signers

Class PSSSigner

java.lang.Object

org.bouncycastle.crypto.signers.PSSSigner

All Implemented Interfaces:

Signer

public class PSSSigner
extends java.lang.Object
implements Signer

RSA-PSS as described in PKCS# 1 v 2.1.

Note: the usual value for the salt length is the number of bytes in the hash function.

The createRawSigner(AsymmetricBlockCipher, Digest) family builds a signer that operates on a pre-computed message hash (mHash) rather than the message itself. RFC 8017 (PKCS#1 v2.2) sec. 9.1 EMSA-PSS first hashes the message M to mHash and then salts and re-hashes; these factories replace only that first hash with a Prehash pass-through, so the caller supplies mHash via update(...) and the signer still performs the salt / M' / second-hash / masking steps. The bytes supplied must be exactly the content digest's output length, otherwise signing or verification fails with "Incorrect prehash size". This is the lightweight-API equivalent of a "sign/verify pre-computed hash" entry point (github #1145). See org.bouncycastle.crypto.examples.RSAPSSPreComputedHashExample.

Field Summary

Fields

Modifier and Type	Field	Description
static byte	TRAILER_IMPLICIT

Constructor Summary

Constructors

Constructor	Description
PSSSigner(AsymmetricBlockCipher cipher, Digest digest, byte[] salt)
PSSSigner(AsymmetricBlockCipher cipher, Digest digest, int sLen)	basic constructor
PSSSigner(AsymmetricBlockCipher cipher, Digest digest, int sLen, byte trailer)
PSSSigner(AsymmetricBlockCipher cipher, Digest contentDigest, Digest mgfDigest, byte[] salt)
PSSSigner(AsymmetricBlockCipher cipher, Digest contentDigest, Digest mgfDigest, byte[] salt, byte trailer)
PSSSigner(AsymmetricBlockCipher cipher, Digest contentDigest, Digest mgfDigest, int sLen)
PSSSigner(AsymmetricBlockCipher cipher, Digest contentDigest, Digest mgfDigest, int sLen, byte trailer)

Method Summary

Modifier and Type	Method	Description
static PSSSigner	createRawSigner(AsymmetricBlockCipher cipher, Digest digest)	Create a PSS signer/verifier that consumes a pre-computed message hash.
static PSSSigner	createRawSigner(AsymmetricBlockCipher cipher, Digest contentDigest, Digest mgfDigest, byte[] salt, byte trailer)	Create a PSS signer/verifier that consumes a pre-computed message hash, using a fixed salt (chiefly for known-answer testing where the salt must be reproducible).
static PSSSigner	createRawSigner(AsymmetricBlockCipher cipher, Digest contentDigest, Digest mgfDigest, int sLen, byte trailer)	Create a PSS signer/verifier that consumes a pre-computed message hash, with the MGF digest, salt length and trailer specified explicitly.
byte[]	generateSignature()	generate a signature for the message we've been loaded with using the key we were initialised with.
void	init(boolean forSigning, CipherParameters param)	Initialise the signer for signing or verification.
void	reset()	reset the internal state
void	update(byte b)	update the internal digest with the byte b
void	update(byte[] in, int off, int len)	update the internal digest with the byte array in
boolean	verifySignature(byte[] signature)	return true if the internal state represents the signature described in the passed in array.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

TRAILER_IMPLICIT

public static final byte TRAILER_IMPLICIT

See Also:

Constant Field Values

Constructor Detail

PSSSigner

public PSSSigner(AsymmetricBlockCipher cipher,
                 Digest digest,
                 int sLen)

basic constructor

Parameters:

cipher - the asymmetric cipher to use.

digest - the digest to use.

sLen - the length of the salt to use (in bytes).

PSSSigner

public PSSSigner(AsymmetricBlockCipher cipher,
                 Digest contentDigest,
                 Digest mgfDigest,
                 int sLen)

PSSSigner

public PSSSigner(AsymmetricBlockCipher cipher,
                 Digest digest,
                 int sLen,
                 byte trailer)

PSSSigner

public PSSSigner(AsymmetricBlockCipher cipher,
                 Digest contentDigest,
                 Digest mgfDigest,
                 int sLen,
                 byte trailer)

PSSSigner

public PSSSigner(AsymmetricBlockCipher cipher,
                 Digest digest,
                 byte[] salt)

PSSSigner

public PSSSigner(AsymmetricBlockCipher cipher,
                 Digest contentDigest,
                 Digest mgfDigest,
                 byte[] salt)

PSSSigner

public PSSSigner(AsymmetricBlockCipher cipher,
                 Digest contentDigest,
                 Digest mgfDigest,
                 byte[] salt,
                 byte trailer)

Method Detail

createRawSigner

public static PSSSigner createRawSigner(AsymmetricBlockCipher cipher,
                                        Digest digest)

Create a PSS signer/verifier that consumes a pre-computed message hash. The caller feeds exactly digest.getDigestSize() bytes (the hash of the message under digest) through update(...) before generateSignature() / verifySignature(...); digest is also used for the EMSA-PSS second hash and the MGF1 mask, and the salt length defaults to the digest output length with the implicit (0xBC) trailer.

Parameters:

cipher - the asymmetric cipher to use (e.g. a configured RSAEngine).

digest - the digest the supplied hash was produced with.

createRawSigner

public static PSSSigner createRawSigner(AsymmetricBlockCipher cipher,
                                        Digest contentDigest,
                                        Digest mgfDigest,
                                        int sLen,
                                        byte trailer)

Create a PSS signer/verifier that consumes a pre-computed message hash, with the MGF digest, salt length and trailer specified explicitly. The caller feeds exactly contentDigest.getDigestSize() bytes (the pre-computed hash) through update(...); contentDigest performs the EMSA-PSS second hash and mgfDigest drives the MGF1 mask.

Parameters:

cipher - the asymmetric cipher to use.

contentDigest - the digest the supplied hash was produced with, also used for the second hash.

mgfDigest - the digest to use for the MGF1 mask generation function.

sLen - the length of the salt to use (in bytes).

trailer - the trailer byte (usually TRAILER_IMPLICIT).

createRawSigner

public static PSSSigner createRawSigner(AsymmetricBlockCipher cipher,
                                        Digest contentDigest,
                                        Digest mgfDigest,
                                        byte[] salt,
                                        byte trailer)

Create a PSS signer/verifier that consumes a pre-computed message hash, using a fixed salt (chiefly for known-answer testing where the salt must be reproducible). The caller feeds exactly contentDigest.getDigestSize() bytes (the pre-computed hash) through update(...).

Parameters:

cipher - the asymmetric cipher to use.

contentDigest - the digest the supplied hash was produced with, also used for the second hash.

mgfDigest - the digest to use for the MGF1 mask generation function.

salt - the fixed salt to use.

trailer - the trailer byte (usually TRAILER_IMPLICIT).

init

public void init(boolean forSigning,
                 CipherParameters param)

Description copied from interface: Signer

Initialise the signer for signing or verification.

Specified by:

init in interface Signer

Parameters:

forSigning - true if for signing, false otherwise

param - necessary parameters.

update

public void update(byte b)

update the internal digest with the byte b

Specified by:

update in interface Signer

update

public void update(byte[] in,
                   int off,
                   int len)

update the internal digest with the byte array in

Specified by:

update in interface Signer

reset

public void reset()

reset the internal state

Specified by:

reset in interface Signer

generateSignature

public byte[] generateSignature()
                         throws CryptoException,
                                DataLengthException

generate a signature for the message we've been loaded with using the key we were initialised with.

Specified by:

generateSignature in interface Signer

Throws:

CryptoException

DataLengthException

verifySignature

public boolean verifySignature(byte[] signature)

return true if the internal state represents the signature described in the passed in array.

Specified by:

verifySignature in interface Signer