Class KeyExchanger

java.lang.Object

net.schmizz.sshj.transport.KeyExchanger

All Implemented Interfaces:

ErrorNotifiable, SSHPacketHandler

final class KeyExchanger
extends Object
implements SSHPacketHandler, ErrorNotifiable

Algorithm negotiation and key exchange.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static enum	KeyExchanger.Expected

Nested classes/interfaces inherited from interface ErrorNotifiable

ErrorNotifiable.Util

Field Summary

Fields

Modifier and Type	Field	Description
private final Queue<AlgorithmsVerifier>	algorithmVerifiers
private Proposal	clientProposal
private final Event<TransportException>	done
private KeyExchanger.Expected	expected	What we are expecting from the next packet
private final Queue<HostKeyVerifier>	hostVerifiers	HostKeyVerifier.verify(String, int, java.security.PublicKey) is invoked by verifyHost(PublicKey) when we are ready to verify the the server's host key.
private final AtomicBoolean	initialKex
private KeyExchange	kex	Instance of negotiated key exchange algorithm
private final Event<TransportException>	kexInitSent
private final AtomicBoolean	kexOngoing
private final org.slf4j.Logger	log
private NegotiatedAlgorithms	negotiatedAlgs
private byte[]	sessionID	Computed session ID
private final AtomicBoolean	strictKex
private final TransportImpl	transport

Constructor Summary

Constructors

Constructor	Description
KeyExchanger(TransportImpl trans)

Method Summary

Modifier and Type	Method	Description
(package private) void	addAlgorithmsVerifier(AlgorithmsVerifier verifier)
(package private) void	addHostKeyVerifier(HostKeyVerifier hkv)	Add a callback for host key verification.
private void	ensureKexOngoing()
private static void	ensureReceivedMatchesExpected(Message got, Message expected)
private List<String>	findKnownHostAlgs(String hostname, int port)
(package private) byte[]	getSessionID()	Returns the session identifier computed during key exchange.
private void	gotKexInit(SSHPacket buf)
private void	gotNewKeys()
private void	gotStrictKexInfo(Proposal serverProposal)
void	handle(Message msg, SSHPacket buf)	Delegate handling of some SSH packet to this object.
(package private) boolean	isInitialKex()
(package private) boolean	isKexDone()
(package private) boolean	isKexOngoing()
private boolean	isKeyExchangeAllowed()	Key exchange can be initiated exactly once while connecting or later after authentication when re-keying.
(package private) boolean	isStrictKex()
void	notifyError(SSHException error)	Notifies this object of an error.
private static byte[]	resizedKey(byte[] E, int blockSize, Digest hash, BigInteger K, byte[] H)	Private method used while putting new keys into use that will resize the key used to initialize the cipher to the needed length.
private void	sendKexInit()	Sends SSH_MSG_KEXINIT and sets the kexInitSent event.
private void	sendNewKeys()
private void	setKexDone()
(package private) void	startKex(boolean waitForDone)	Starts key exchange by sending a SSH_MSG_KEXINIT packet.
private void	verifyHost(PublicKey key)	Tries to validate host key with all the host key verifiers known to this instance ( hostVerifiers)
(package private) void	waitForDone()

Methods inherited from class Object

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

Field Details

log

private final org.slf4j.Logger log

transport

private final TransportImpl transport

hostVerifiers

private final Queue<HostKeyVerifier> hostVerifiers

HostKeyVerifier.verify(String, int, java.security.PublicKey) is invoked by verifyHost(PublicKey) when we are ready to verify the the server's host key.

algorithmVerifiers

private final Queue<AlgorithmsVerifier> algorithmVerifiers

kexOngoing

private final AtomicBoolean kexOngoing

initialKex

private final AtomicBoolean initialKex

strictKex

private final AtomicBoolean strictKex

expected

private KeyExchanger.Expected expected

What we are expecting from the next packet

kex

private KeyExchange kex

Instance of negotiated key exchange algorithm

sessionID

private byte[] sessionID

Computed session ID

clientProposal

private Proposal clientProposal

negotiatedAlgs

private NegotiatedAlgorithms negotiatedAlgs

kexInitSent

private final Event<TransportException> kexInitSent

done

private final Event<TransportException> done

Constructor Details

KeyExchanger

KeyExchanger(TransportImpl trans)

Method Details

addHostKeyVerifier

void addHostKeyVerifier(HostKeyVerifier hkv)

Add a callback for host key verification.

Any of the HostKeyVerifier implementations added this way can deem a host key to be acceptable, allowing key exchange to successfully complete. Otherwise, a TransportException will result during key exchange.

Parameters:

hkv - object whose HostKeyVerifier.verify(String, int, PublicKey) method will be invoked

addAlgorithmsVerifier

void addAlgorithmsVerifier(AlgorithmsVerifier verifier)

getSessionID

byte[] getSessionID()

Returns the session identifier computed during key exchange.

Returns:

session identifier as a byte array

isKexDone

boolean isKexDone()

Returns:

whether key exchange has been completed

isKexOngoing

boolean isKexOngoing()

Returns:

whether key exchange is currently ongoing

isStrictKex

boolean isStrictKex()

isInitialKex

boolean isInitialKex()

startKex

void startKex(boolean waitForDone)
       throws TransportException

Starts key exchange by sending a SSH_MSG_KEXINIT packet. Key exchange needs to be done once mandatorily after initializing the Transport for it to be usable and may be initiated at any later point e.g. if algorithms have changed and should be renegotiated.

Parameters:

waitForDone - whether should block till key exchange completed

Throws:

TransportException - if there is an error during key exchange

isKeyExchangeAllowed

private boolean isKeyExchangeAllowed()

Key exchange can be initiated exactly once while connecting or later after authentication when re-keying.

waitForDone

void waitForDone()
          throws TransportException

Throws:

TransportException

ensureKexOngoing

private void ensureKexOngoing()
                       throws TransportException

Throws:

TransportException

ensureReceivedMatchesExpected

private static void ensureReceivedMatchesExpected(Message got,
 Message expected)
                                           throws TransportException

Throws:

TransportException

sendKexInit

private void sendKexInit()
                  throws TransportException

Sends SSH_MSG_KEXINIT and sets the kexInitSent event.

Throws:

TransportException

findKnownHostAlgs

private List<String> findKnownHostAlgs(String hostname,
 int port)

sendNewKeys

private void sendNewKeys()
                  throws TransportException

Throws:

TransportException

verifyHost

private void verifyHost(PublicKey key)
                 throws TransportException

Tries to validate host key with all the host key verifiers known to this instance ( hostVerifiers)

Parameters:

key - the host key to verify

Throws:

TransportException

setKexDone

private void setKexDone()

gotKexInit

private void gotKexInit(SSHPacket buf)
                 throws TransportException

Throws:

TransportException

gotStrictKexInfo

private void gotStrictKexInfo(Proposal serverProposal)
                       throws TransportException

Throws:

TransportException

resizedKey

private static byte[] resizedKey(byte[] E,
 int blockSize,
 Digest hash,
 BigInteger K,
 byte[] H)

Private method used while putting new keys into use that will resize the key used to initialize the cipher to the needed length.

Parameters:

E - the key to resize

blockSize - the cipher block size

hash - the hash algorithm

K - the key exchange K parameter

H - the key exchange H parameter

Returns:

the resized key

gotNewKeys

private void gotNewKeys()

handle

public void handle(Message msg,
 SSHPacket buf)
            throws TransportException

Description copied from interface: SSHPacketHandler

Delegate handling of some SSH packet to this object.

Specified by:

handle in interface SSHPacketHandler

Parameters:

msg - the SSH message identifier

buf - SSHPacket containing rest of the request

Throws:

TransportException

notifyError

public void notifyError(SSHException error)

Description copied from interface: ErrorNotifiable

Notifies this object of an error.

Specified by:

notifyError in interface ErrorNotifiable