src/main/java/com/trilead/ssh2/crypto/dh/GenericDhExchange.java
package com.trilead.ssh2.crypto.dh;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.math.BigInteger;
import com.trilead.ssh2.crypto.digest.HashForSSH2Types;
import com.trilead.ssh2.log.Logger;
/**
* DhExchange.
*
* @author Christian Plattner, plattner@trilead.com
* @version $Id: DhExchange.java,v 1.2 2008/04/01 12:38:09 cplattne Exp $
*/
public abstract class GenericDhExchange
{
private static final Logger log = Logger.getLogger(GenericDhExchange.class);
/* Shared secret */
BigInteger sharedSecret;
protected GenericDhExchange()
{
}
public static GenericDhExchange getInstance(String algo) {
if (Curve25519Exchange.NAME.equals(algo) || Curve25519Exchange.ALT_NAME.equals(algo)) {
return new Curve25519Exchange();
}
if (algo.startsWith("ecdh-sha2-")) {
return new EcDhExchange();
} else {
return new DhExchange();
}
}
public abstract void init(String name) throws IOException;
/**
* @return Returns the e (public value)
* @throws IllegalStateException
*/
public abstract byte[] getE();
/**
* @return Returns the server's e (public value)
* @throws IllegalStateException
*/
protected abstract byte[] getServerE();
/**
* @return Returns the shared secret k.
* @throws IllegalStateException
*/
public BigInteger getK()
{
if (sharedSecret == null)
throw new IllegalStateException("Shared secret not yet known, need f first!");
return sharedSecret;
}
/**
* @param f
*/
public abstract void setF(byte[] f) throws IOException;
public byte[] calculateH(byte[] clientversion, byte[] serverversion, byte[] clientKexPayload,
byte[] serverKexPayload, byte[] hostKey) throws UnsupportedEncodingException
{
HashForSSH2Types hash = new HashForSSH2Types(getHashAlgo());
if (log.isEnabled())
{
log.log(90, "Client: '" + new String(clientversion) + "'");
log.log(90, "Server: '" + new String(serverversion) + "'");
}
hash.updateByteString(clientversion);
hash.updateByteString(serverversion);
hash.updateByteString(clientKexPayload);
hash.updateByteString(serverKexPayload);
hash.updateByteString(hostKey);
hash.updateByteString(getE());
hash.updateByteString(getServerE());
hash.updateBigInt(sharedSecret);
return hash.getDigest();
}
public abstract String getHashAlgo();
}