com.jcraft.jsch

Class KeyExchange

java.lang.Object

com.jcraft.jsch.KeyExchange

Direct Known Subclasses:

DHECN, DHG1, DHG14, DHGEX

public abstract class KeyExchange
extends Object

Usually not to be used by applications. Abstract base class for key exchange algorithms. The concrete implementation will be chosen based on the configuration and on the negotiation between client and server.

See Also:

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

Field Summary

Fields

Modifier and Type	Field and Description
protected int	DSS
protected int	ECDSA
protected byte[]	H
protected byte[]	K
protected byte[]	K_S
protected int	RSA
protected Session	session
protected HASH	sha
static int	STATE_END constant used by getState() when no more key exchange packet is expected.

Constructor Summary

Constructors

Constructor and Description
KeyExchange()

Method Summary

Modifier and Type	Method and Description
String	getFingerPrint() returns the finger print of the server's public key.
String	getKeyAlgorithName()
String	getKeyType() Returns the type of key used by the server.
abstract int	getState() returns the identifier of the next SSH packet expected, or STATE_END if the KeyExchange was already successfully finished.
protected static String[]	guess(byte[] I_S, byte[] I_C)
abstract void	init(Session session, byte[] V_S, byte[] V_C, byte[] I_S, byte[] I_C) Initializes the key exchange object.
abstract boolean	next(Buffer buf) Does the next step in the key exchange algorithm.
protected byte[]	normalize(byte[] secret)
protected boolean	verify(String alg, byte[] K_S, int index, byte[] sig_of_H)

Methods inherited from class java.lang.Object

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

Field Detail

STATE_END

public static final int STATE_END

constant used by getState() when no more key exchange packet is expected.

See Also:

Constant Field Values

session

protected Session session

sha

protected HASH sha

K

protected byte[] K

H

protected byte[] H

K_S

protected byte[] K_S

RSA

protected final int RSA

See Also:

Constant Field Values

DSS

protected final int DSS

See Also:

Constant Field Values

ECDSA

protected final int ECDSA

See Also:

Constant Field Values

Constructor Detail

KeyExchange

public KeyExchange()

Method Detail

init

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

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.

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 abstract boolean next(Buffer buf)
                      throws Exception

Does the next step in the key exchange algorithm.

Parameters:

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

Returns:

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

Throws:

Exception

getState

public abstract int getState()

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

getKeyType

public String getKeyType()

Returns the type of key used by the server. With current algorithms, this is either "DSA", "RSA" or "ECDSA".

getKeyAlgorithName

public String getKeyAlgorithName()

guess

protected static String[] guess(byte[] I_S,
                                byte[] I_C)

getFingerPrint

public String getFingerPrint()

returns the finger print of the server's public key. This uses the HASH implementation given by session.getConfig("md5").

Returns:

the (lowercase) hexadecimal representation of the MD5 hash of the server's public key.

normalize

protected byte[] normalize(byte[] secret)

verify

protected boolean verify(String alg,
                         byte[] K_S,
                         int index,
                         byte[] sig_of_H)
                  throws Exception

Throws:

Exception