com.jcraft.jsch

Class DHGEX

java.lang.Object

com.jcraft.jsch.KeyExchange

com.jcraft.jsch.DHGEX

Direct Known Subclasses:

DHGEX256

public class DHGEX
extends KeyExchange

Usually not to be used by applications. Implements the key exchange method diffie-hellman-group-exchange-sha1, allowing the server to propose a group (i.e. prime number and generator) in which the calculations for key exchange will be done. For the actual cryptographic calculations we delegate to an implementation of DH.

See Also:

RFC 4419, Diffie-Hellman Group Exchange for the Secure Shell (SSH) Transport Layer Protocol

Field Summary

Fields

Modifier and Type	Field and Description
protected String	hash

Fields inherited from class com.jcraft.jsch.KeyExchange

DSS, ECDSA, H, K, K_S, RSA, session, sha, STATE_END

Constructor Summary

Constructors

Constructor and Description
DHGEX()

Method Summary

Modifier and Type	Method and Description
protected int	check2048(Class c, int _max)
int	getState() returns the identifier of the next SSH packet expected, or KeyExchange.STATE_END if the KeyExchange was already successfully finished.
void	init(Session session, byte[] V_S, byte[] V_C, byte[] I_S, byte[] I_C) Initializes the key exchange object.
boolean	next(Buffer _buf) Does the next step in the key exchange algorithm.

Methods inherited from class com.jcraft.jsch.KeyExchange

getFingerPrint, getKeyAlgorithName, getKeyType, guess, normalize, verify

Methods inherited from class java.lang.Object

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

Field Detail

hash

protected String hash

Constructor Detail

DHGEX

public DHGEX()

Method Detail

init

public void init(Session session,
                 byte[] V_S,
                 byte[] V_C,
                 byte[] I_S,
                 byte[] I_C)
          throws Exception

Description copied from class: KeyExchange

Initializes the key exchange object. The parameters here seem to be specific to the Diffie-Hellman Key exchange specified by RFC 4253, other Key Exchange mechanisms might need other parameters.

Specified by:

init in class KeyExchange

Parameters:

session - the session object.

V_S - the server's identification string sent before negotiation

V_C - the client's identification string sent before negotiation

I_S - the server's complete SSH_MSG_KEXINIT message.

I_C - the server's complete SSH_MSG_KEXINIT message.

Throws:

Exception

See Also:

RFC 4253, 7. Key Exchange, RFC 4253, 8. Diffie-Hellman Key Exchange

next

public boolean next(Buffer _buf)
             throws Exception

Description copied from class: KeyExchange

Does the next step in the key exchange algorithm.

Specified by:

next in class KeyExchange

Parameters:

_buf - the received packet. It will have the same message-type as KeyExchange.getState() returned before.

Returns:

false if there was some problem, true if everything was okay.

Throws:

Exception

getState

public int getState()

Description copied from class: KeyExchange

returns the identifier of the next SSH packet expected, or KeyExchange.STATE_END if the KeyExchange was already successfully finished.

Specified by:

getState in class KeyExchange

check2048

protected int check2048(Class c,
                        int _max)
                 throws Exception

Throws:

Exception