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com.trilead.ssh2.transport.KexManager Maven / Gradle / Ivy
Ganymed SSH2 for Java is a library which implements the SSH-2 protocol in pure Java
package com.trilead.ssh2.transport;
import java.io.IOException;
import java.io.InterruptedIOException;
import java.security.SecureRandom;
import com.trilead.ssh2.ConnectionInfo;
import com.trilead.ssh2.DHGexParameters;
import com.trilead.ssh2.ServerHostKeyVerifier;
import com.trilead.ssh2.crypto.CryptoWishList;
import com.trilead.ssh2.crypto.KeyMaterial;
import com.trilead.ssh2.crypto.cipher.BlockCipher;
import com.trilead.ssh2.crypto.cipher.BlockCipherFactory;
import com.trilead.ssh2.crypto.dh.DhExchange;
import com.trilead.ssh2.crypto.dh.DhGroupExchange;
import com.trilead.ssh2.crypto.digest.MAC;
import com.trilead.ssh2.log.Logger;
import com.trilead.ssh2.packets.PacketKexDHInit;
import com.trilead.ssh2.packets.PacketKexDHReply;
import com.trilead.ssh2.packets.PacketKexDhGexGroup;
import com.trilead.ssh2.packets.PacketKexDhGexInit;
import com.trilead.ssh2.packets.PacketKexDhGexReply;
import com.trilead.ssh2.packets.PacketKexDhGexRequest;
import com.trilead.ssh2.packets.PacketKexDhGexRequestOld;
import com.trilead.ssh2.packets.PacketKexInit;
import com.trilead.ssh2.packets.PacketNewKeys;
import com.trilead.ssh2.packets.Packets;
import com.trilead.ssh2.signature.DSAPublicKey;
import com.trilead.ssh2.signature.DSASHA1Verify;
import com.trilead.ssh2.signature.DSASignature;
import com.trilead.ssh2.signature.RSAPublicKey;
import com.trilead.ssh2.signature.RSASHA1Verify;
import com.trilead.ssh2.signature.RSASignature;
/**
* KexManager.
*
* @author Christian Plattner, [email protected]
* @version $Id: KexManager.java,v 1.1 2007/10/15 12:49:56 cplattne Exp $
*/
public class KexManager
{
private static final Logger log = Logger.getLogger(KexManager.class);
KexState kxs;
int kexCount = 0;
KeyMaterial km;
byte[] sessionId;
ClientServerHello csh;
final Object accessLock = new Object();
ConnectionInfo lastConnInfo = null;
boolean connectionClosed = false;
boolean ignore_next_kex_packet = false;
final TransportManager tm;
CryptoWishList nextKEXcryptoWishList;
DHGexParameters nextKEXdhgexParameters;
ServerHostKeyVerifier verifier;
final String hostname;
final int port;
final SecureRandom rnd;
public KexManager(TransportManager tm, ClientServerHello csh, CryptoWishList initialCwl, String hostname, int port,
ServerHostKeyVerifier keyVerifier, SecureRandom rnd)
{
this.tm = tm;
this.csh = csh;
this.nextKEXcryptoWishList = initialCwl;
this.nextKEXdhgexParameters = new DHGexParameters();
this.hostname = hostname;
this.port = port;
this.verifier = keyVerifier;
this.rnd = rnd;
}
public ConnectionInfo getOrWaitForConnectionInfo(int minKexCount) throws IOException
{
synchronized (accessLock)
{
while (true)
{
if ((lastConnInfo != null) && (lastConnInfo.keyExchangeCounter >= minKexCount))
return lastConnInfo;
if (connectionClosed)
throw (IOException) new IOException("Key exchange was not finished, connection is closed.")
.initCause(tm.getReasonClosedCause());
try
{
accessLock.wait();
}
catch (InterruptedException e)
{
throw new InterruptedIOException();
}
}
}
}
private String getFirstMatch(String[] client, String[] server) throws NegotiateException
{
if (client == null || server == null)
throw new IllegalArgumentException();
if (client.length == 0)
return null;
for (int i = 0; i < client.length; i++)
{
for (int j = 0; j < server.length; j++)
{
if (client[i].equals(server[j]))
return client[i];
}
}
throw new NegotiateException();
}
private boolean compareFirstOfNameList(String[] a, String[] b)
{
if (a == null || b == null)
throw new IllegalArgumentException();
if ((a.length == 0) && (b.length == 0))
return true;
if ((a.length == 0) || (b.length == 0))
return false;
return (a[0].equals(b[0]));
}
private boolean isGuessOK(KexParameters cpar, KexParameters spar)
{
if (cpar == null || spar == null)
throw new IllegalArgumentException();
if (compareFirstOfNameList(cpar.kex_algorithms, spar.kex_algorithms) == false)
{
return false;
}
if (compareFirstOfNameList(cpar.server_host_key_algorithms, spar.server_host_key_algorithms) == false)
{
return false;
}
/*
* We do NOT check here if the other algorithms can be agreed on, this
* is just a check if kex_algorithms and server_host_key_algorithms were
* guessed right!
*/
return true;
}
private NegotiatedParameters mergeKexParameters(KexParameters client, KexParameters server)
{
NegotiatedParameters np = new NegotiatedParameters();
try
{
np.kex_algo = getFirstMatch(client.kex_algorithms, server.kex_algorithms);
log.log(20, "kex_algo=" + np.kex_algo);
np.server_host_key_algo = getFirstMatch(client.server_host_key_algorithms,
server.server_host_key_algorithms);
log.log(20, "server_host_key_algo=" + np.server_host_key_algo);
np.enc_algo_client_to_server = getFirstMatch(client.encryption_algorithms_client_to_server,
server.encryption_algorithms_client_to_server);
np.enc_algo_server_to_client = getFirstMatch(client.encryption_algorithms_server_to_client,
server.encryption_algorithms_server_to_client);
log.log(20, "enc_algo_client_to_server=" + np.enc_algo_client_to_server);
log.log(20, "enc_algo_server_to_client=" + np.enc_algo_server_to_client);
np.mac_algo_client_to_server = getFirstMatch(client.mac_algorithms_client_to_server,
server.mac_algorithms_client_to_server);
np.mac_algo_server_to_client = getFirstMatch(client.mac_algorithms_server_to_client,
server.mac_algorithms_server_to_client);
log.log(20, "mac_algo_client_to_server=" + np.mac_algo_client_to_server);
log.log(20, "mac_algo_server_to_client=" + np.mac_algo_server_to_client);
np.comp_algo_client_to_server = getFirstMatch(client.compression_algorithms_client_to_server,
server.compression_algorithms_client_to_server);
np.comp_algo_server_to_client = getFirstMatch(client.compression_algorithms_server_to_client,
server.compression_algorithms_server_to_client);
log.log(20, "comp_algo_client_to_server=" + np.comp_algo_client_to_server);
log.log(20, "comp_algo_server_to_client=" + np.comp_algo_server_to_client);
}
catch (NegotiateException e)
{
return null;
}
try
{
np.lang_client_to_server = getFirstMatch(client.languages_client_to_server,
server.languages_client_to_server);
}
catch (NegotiateException e1)
{
np.lang_client_to_server = null;
}
try
{
np.lang_server_to_client = getFirstMatch(client.languages_server_to_client,
server.languages_server_to_client);
}
catch (NegotiateException e2)
{
np.lang_server_to_client = null;
}
if (isGuessOK(client, server))
np.guessOK = true;
return np;
}
public synchronized void initiateKEX(CryptoWishList cwl, DHGexParameters dhgex) throws IOException
{
nextKEXcryptoWishList = cwl;
nextKEXdhgexParameters = dhgex;
if (kxs == null)
{
kxs = new KexState();
kxs.dhgexParameters = nextKEXdhgexParameters;
PacketKexInit kp = new PacketKexInit(nextKEXcryptoWishList, rnd);
kxs.localKEX = kp;
tm.sendKexMessage(kp.getPayload());
}
}
private boolean establishKeyMaterial()
{
try
{
int mac_cs_key_len = MAC.getKeyLen(kxs.np.mac_algo_client_to_server);
int enc_cs_key_len = BlockCipherFactory.getKeySize(kxs.np.enc_algo_client_to_server);
int enc_cs_block_len = BlockCipherFactory.getBlockSize(kxs.np.enc_algo_client_to_server);
int mac_sc_key_len = MAC.getKeyLen(kxs.np.mac_algo_server_to_client);
int enc_sc_key_len = BlockCipherFactory.getKeySize(kxs.np.enc_algo_server_to_client);
int enc_sc_block_len = BlockCipherFactory.getBlockSize(kxs.np.enc_algo_server_to_client);
km = KeyMaterial.create("SHA1", kxs.H, kxs.K, sessionId, enc_cs_key_len, enc_cs_block_len, mac_cs_key_len,
enc_sc_key_len, enc_sc_block_len, mac_sc_key_len);
}
catch (IllegalArgumentException e)
{
return false;
}
return true;
}
private void finishKex() throws IOException
{
if (sessionId == null)
sessionId = kxs.H;
establishKeyMaterial();
/* Tell the other side that we start using the new material */
PacketNewKeys ign = new PacketNewKeys();
tm.sendKexMessage(ign.getPayload());
BlockCipher cbc;
MAC mac;
try
{
cbc = BlockCipherFactory.createCipher(kxs.np.enc_algo_client_to_server, true, km.enc_key_client_to_server,
km.initial_iv_client_to_server);
mac = new MAC(kxs.np.mac_algo_client_to_server, km.integrity_key_client_to_server);
}
catch (IllegalArgumentException e1)
{
throw new IOException("Fatal error during MAC startup!");
}
tm.changeSendCipher(cbc, mac);
tm.kexFinished();
}
public static final String[] getDefaultServerHostkeyAlgorithmList()
{
return new String[] { "ssh-rsa", "ssh-dss" };
}
public static final void checkServerHostkeyAlgorithmsList(String[] algos)
{
for (int i = 0; i < algos.length; i++)
{
if (("ssh-rsa".equals(algos[i]) == false) && ("ssh-dss".equals(algos[i]) == false))
throw new IllegalArgumentException("Unknown server host key algorithm '" + algos[i] + "'");
}
}
public static final String[] getDefaultKexAlgorithmList()
{
return new String[] { "diffie-hellman-group-exchange-sha1", "diffie-hellman-group14-sha1",
"diffie-hellman-group1-sha1" };
}
public static final void checkKexAlgorithmList(String[] algos)
{
for (int i = 0; i < algos.length; i++)
{
if ("diffie-hellman-group-exchange-sha1".equals(algos[i]))
continue;
if ("diffie-hellman-group14-sha1".equals(algos[i]))
continue;
if ("diffie-hellman-group1-sha1".equals(algos[i]))
continue;
throw new IllegalArgumentException("Unknown kex algorithm '" + algos[i] + "'");
}
}
private boolean verifySignature(byte[] sig, byte[] hostkey) throws IOException
{
if (kxs.np.server_host_key_algo.equals("ssh-rsa"))
{
RSASignature rs = RSASHA1Verify.decodeSSHRSASignature(sig);
RSAPublicKey rpk = RSASHA1Verify.decodeSSHRSAPublicKey(hostkey);
log.log(50, "Verifying ssh-rsa signature");
return RSASHA1Verify.verifySignature(kxs.H, rs, rpk);
}
if (kxs.np.server_host_key_algo.equals("ssh-dss"))
{
DSASignature ds = DSASHA1Verify.decodeSSHDSASignature(sig);
DSAPublicKey dpk = DSASHA1Verify.decodeSSHDSAPublicKey(hostkey);
log.log(50, "Verifying ssh-dss signature");
return DSASHA1Verify.verifySignature(kxs.H, ds, dpk);
}
throw new IOException("Unknown server host key algorithm '" + kxs.np.server_host_key_algo + "'");
}
public synchronized void handleMessage(byte[] msg, int msglen) throws IOException
{
PacketKexInit kip;
if (msg == null)
{
synchronized (accessLock)
{
connectionClosed = true;
accessLock.notifyAll();
return;
}
}
if ((kxs == null) && (msg[0] != Packets.SSH_MSG_KEXINIT))
throw new IOException("Unexpected KEX message (type " + msg[0] + ")");
if (ignore_next_kex_packet)
{
ignore_next_kex_packet = false;
return;
}
if (msg[0] == Packets.SSH_MSG_KEXINIT)
{
if ((kxs != null) && (kxs.state != 0))
throw new IOException("Unexpected SSH_MSG_KEXINIT message during on-going kex exchange!");
if (kxs == null)
{
/*
* Ah, OK, peer wants to do KEX. Let's be nice and play
* together.
*/
kxs = new KexState();
kxs.dhgexParameters = nextKEXdhgexParameters;
kip = new PacketKexInit(nextKEXcryptoWishList, rnd);
kxs.localKEX = kip;
tm.sendKexMessage(kip.getPayload());
}
kip = new PacketKexInit(msg, 0, msglen);
kxs.remoteKEX = kip;
kxs.np = mergeKexParameters(kxs.localKEX.getKexParameters(), kxs.remoteKEX.getKexParameters());
if (kxs.np == null)
throw new IOException("Cannot negotiate, proposals do not match.");
if (kxs.remoteKEX.isFirst_kex_packet_follows() && (kxs.np.guessOK == false))
{
/*
* Guess was wrong, we need to ignore the next kex packet.
*/
ignore_next_kex_packet = true;
}
if (kxs.np.kex_algo.equals("diffie-hellman-group-exchange-sha1"))
{
if (kxs.dhgexParameters.getMin_group_len() == 0)
{
PacketKexDhGexRequestOld dhgexreq = new PacketKexDhGexRequestOld(kxs.dhgexParameters);
tm.sendKexMessage(dhgexreq.getPayload());
}
else
{
PacketKexDhGexRequest dhgexreq = new PacketKexDhGexRequest(kxs.dhgexParameters);
tm.sendKexMessage(dhgexreq.getPayload());
}
kxs.state = 1;
return;
}
if (kxs.np.kex_algo.equals("diffie-hellman-group1-sha1")
|| kxs.np.kex_algo.equals("diffie-hellman-group14-sha1"))
{
kxs.dhx = new DhExchange();
if (kxs.np.kex_algo.equals("diffie-hellman-group1-sha1"))
kxs.dhx.init(1, rnd);
else
kxs.dhx.init(14, rnd);
PacketKexDHInit kp = new PacketKexDHInit(kxs.dhx.getE());
tm.sendKexMessage(kp.getPayload());
kxs.state = 1;
return;
}
throw new IllegalStateException("Unkown KEX method!");
}
if (msg[0] == Packets.SSH_MSG_NEWKEYS)
{
if (km == null)
throw new IOException("Peer sent SSH_MSG_NEWKEYS, but I have no key material ready!");
BlockCipher cbc;
MAC mac;
try
{
cbc = BlockCipherFactory.createCipher(kxs.np.enc_algo_server_to_client, false,
km.enc_key_server_to_client, km.initial_iv_server_to_client);
mac = new MAC(kxs.np.mac_algo_server_to_client, km.integrity_key_server_to_client);
}
catch (IllegalArgumentException e1)
{
throw new IOException("Fatal error during MAC startup!");
}
tm.changeRecvCipher(cbc, mac);
ConnectionInfo sci = new ConnectionInfo();
kexCount++;
sci.keyExchangeAlgorithm = kxs.np.kex_algo;
sci.keyExchangeCounter = kexCount;
sci.clientToServerCryptoAlgorithm = kxs.np.enc_algo_client_to_server;
sci.serverToClientCryptoAlgorithm = kxs.np.enc_algo_server_to_client;
sci.clientToServerMACAlgorithm = kxs.np.mac_algo_client_to_server;
sci.serverToClientMACAlgorithm = kxs.np.mac_algo_server_to_client;
sci.serverHostKeyAlgorithm = kxs.np.server_host_key_algo;
sci.serverHostKey = kxs.hostkey;
synchronized (accessLock)
{
lastConnInfo = sci;
accessLock.notifyAll();
}
kxs = null;
return;
}
if ((kxs == null) || (kxs.state == 0))
throw new IOException("Unexpected Kex submessage!");
if (kxs.np.kex_algo.equals("diffie-hellman-group-exchange-sha1"))
{
if (kxs.state == 1)
{
PacketKexDhGexGroup dhgexgrp = new PacketKexDhGexGroup(msg, 0, msglen);
kxs.dhgx = new DhGroupExchange(dhgexgrp.getP(), dhgexgrp.getG());
kxs.dhgx.init(rnd);
PacketKexDhGexInit dhgexinit = new PacketKexDhGexInit(kxs.dhgx.getE());
tm.sendKexMessage(dhgexinit.getPayload());
kxs.state = 2;
return;
}
if (kxs.state == 2)
{
PacketKexDhGexReply dhgexrpl = new PacketKexDhGexReply(msg, 0, msglen);
kxs.hostkey = dhgexrpl.getHostKey();
if (verifier != null)
{
boolean vres = false;
try
{
vres = verifier.verifyServerHostKey(hostname, port, kxs.np.server_host_key_algo, kxs.hostkey);
}
catch (Exception e)
{
throw (IOException) new IOException(
"The server hostkey was not accepted by the verifier callback.").initCause(e);
}
if (vres == false)
throw new IOException("The server hostkey was not accepted by the verifier callback");
}
kxs.dhgx.setF(dhgexrpl.getF());
try
{
kxs.H = kxs.dhgx.calculateH(csh.getClientString(), csh.getServerString(),
kxs.localKEX.getPayload(), kxs.remoteKEX.getPayload(), dhgexrpl.getHostKey(),
kxs.dhgexParameters);
}
catch (IllegalArgumentException e)
{
throw (IOException) new IOException("KEX error.").initCause(e);
}
boolean res = verifySignature(dhgexrpl.getSignature(), kxs.hostkey);
if (res == false)
throw new IOException("Hostkey signature sent by remote is wrong!");
kxs.K = kxs.dhgx.getK();
finishKex();
kxs.state = -1;
return;
}
throw new IllegalStateException("Illegal State in KEX Exchange!");
}
if (kxs.np.kex_algo.equals("diffie-hellman-group1-sha1")
|| kxs.np.kex_algo.equals("diffie-hellman-group14-sha1"))
{
if (kxs.state == 1)
{
PacketKexDHReply dhr = new PacketKexDHReply(msg, 0, msglen);
kxs.hostkey = dhr.getHostKey();
if (verifier != null)
{
boolean vres = false;
try
{
vres = verifier.verifyServerHostKey(hostname, port, kxs.np.server_host_key_algo, kxs.hostkey);
}
catch (Exception e)
{
throw (IOException) new IOException(
"The server hostkey was not accepted by the verifier callback.").initCause(e);
}
if (vres == false)
throw new IOException("The server hostkey was not accepted by the verifier callback");
}
kxs.dhx.setF(dhr.getF());
try
{
kxs.H = kxs.dhx.calculateH(csh.getClientString(), csh.getServerString(), kxs.localKEX.getPayload(),
kxs.remoteKEX.getPayload(), dhr.getHostKey());
}
catch (IllegalArgumentException e)
{
throw (IOException) new IOException("KEX error.").initCause(e);
}
boolean res = verifySignature(dhr.getSignature(), kxs.hostkey);
if (res == false)
throw new IOException("Hostkey signature sent by remote is wrong!");
kxs.K = kxs.dhx.getK();
finishKex();
kxs.state = -1;
return;
}
}
throw new IllegalStateException("Unkown KEX method! (" + kxs.np.kex_algo + ")");
}
}
