line source
package com.trilead.ssh2.transport;
import java.io.IOException;
import java.security.SecureRandom;
import java.security.interfaces.DSAPublicKey;
import java.security.interfaces.ECPublicKey;
import java.security.interfaces.RSAPublicKey;
import java.util.Set;
import java.util.TreeSet;
import com.trilead.ssh2.ConnectionInfo;
import com.trilead.ssh2.DHGexParameters;
import com.trilead.ssh2.ServerHostKeyVerifier;
import com.trilead.ssh2.compression.CompressionFactory;
import com.trilead.ssh2.compression.ICompressor;
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.DhGroupExchange;
import com.trilead.ssh2.crypto.dh.GenericDhExchange;
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.DSASHA1Verify;
import com.trilead.ssh2.signature.ECDSASHA2Verify;
import com.trilead.ssh2.signature.RSASHA1Verify;
/**
* KexManager.
*
* @author Christian Plattner, plattner@trilead.com
* @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);
private static final Set<String> HOSTKEY_ALGS = new TreeSet<String>();
static {
HOSTKEY_ALGS.add("ecdsa-sha2-nistp256");
HOSTKEY_ALGS.add("ecdsa-sha2-nistp384");
HOSTKEY_ALGS.add("ecdsa-sha2-nistp521");
HOSTKEY_ALGS.add("ssh-rsa");
HOSTKEY_ALGS.add("ssh-dsa");
}
private static final Set<String> KEX_ALGS = new TreeSet<String>();
static {
KEX_ALGS.add("ecdh-sha2-nistp256");
KEX_ALGS.add("ecdh-sha2-nistp384");
KEX_ALGS.add("ecdh-sha2-nistp521");
KEX_ALGS.add("diffie-hellman-group-exchange-sha256");
KEX_ALGS.add("diffie-hellman-group-exchange-sha1");
KEX_ALGS.add("diffie-hellman-group14-sha1");
KEX_ALGS.add("diffie-hellman-group1-sha1");
}
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) {
}
}
}
}
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);
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(kxs.hashAlgo, 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;
ICompressor comp;
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);
comp = CompressionFactory.createCompressor(kxs.np.comp_algo_client_to_server);
}
catch (IllegalArgumentException e1) {
throw new IOException("Fatal error during MAC startup!");
}
tm.changeSendCipher(cbc, mac);
tm.changeSendCompression(comp);
tm.kexFinished();
}
public static final String[] getDefaultServerHostkeyAlgorithmList() {
return HOSTKEY_ALGS.toArray(new String[HOSTKEY_ALGS.size()]);
}
public static final void checkServerHostkeyAlgorithmsList(String[] algos) {
for (int i = 0; i < algos.length; i++) {
if (!HOSTKEY_ALGS.contains(algos[i]))
throw new IllegalArgumentException("Unknown server host key algorithm '" + algos[i] + "'");
}
}
public static final String[] getDefaultKexAlgorithmList() {
return KEX_ALGS.toArray(new String[KEX_ALGS.size()]);
}
public static final void checkKexAlgorithmList(String[] algos) {
for (int i = 0; i < algos.length; i++) {
if (!KEX_ALGS.contains(algos[i]))
throw new IllegalArgumentException("Unknown kex algorithm '" + algos[i] + "'");
}
}
private boolean verifySignature(byte[] sig, byte[] hostkey) throws IOException {
if (kxs.np.server_host_key_algo.startsWith("ecdsa-sha2-")) {
byte[] rs = ECDSASHA2Verify.decodeSSHECDSASignature(sig);
ECPublicKey epk = ECDSASHA2Verify.decodeSSHECDSAPublicKey(hostkey);
log.log(50, "Verifying ecdsa signature");
return ECDSASHA2Verify.verifySignature(kxs.H, rs, epk);
}
if (kxs.np.server_host_key_algo.equals("ssh-rsa")) {
byte[] 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")) {
byte[] 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);
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")
|| kxs.np.kex_algo.equals("diffie-hellman-group-exchange-sha256")) {
if (kxs.dhgexParameters.getMin_group_len() == 0 || csh.server_versioncomment.matches("OpenSSH_2\\.([0-4]\\.|5\\.[0-2]).*")) {
PacketKexDhGexRequestOld dhgexreq = new PacketKexDhGexRequestOld(kxs.dhgexParameters);
tm.sendKexMessage(dhgexreq.getPayload());
}
else {
PacketKexDhGexRequest dhgexreq = new PacketKexDhGexRequest(kxs.dhgexParameters);
tm.sendKexMessage(dhgexreq.getPayload());
}
if (kxs.np.kex_algo.endsWith("sha1")) {
kxs.hashAlgo = "SHA1";
}
else {
kxs.hashAlgo = "SHA-256";
}
kxs.state = 1;
return;
}
if (kxs.np.kex_algo.equals("diffie-hellman-group1-sha1")
|| kxs.np.kex_algo.equals("diffie-hellman-group14-sha1")
|| kxs.np.kex_algo.equals("ecdh-sha2-nistp256")
|| kxs.np.kex_algo.equals("ecdh-sha2-nistp384")
|| kxs.np.kex_algo.equals("ecdh-sha2-nistp521")) {
kxs.dhx = GenericDhExchange.getInstance(kxs.np.kex_algo);
kxs.dhx.init(kxs.np.kex_algo);
kxs.hashAlgo = kxs.dhx.getHashAlgo();
PacketKexDHInit kp = new PacketKexDHInit(kxs.dhx.getE());
tm.sendKexMessage(kp.getPayload());
kxs.state = 1;
return;
}
throw new IllegalStateException("Unknown 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;
ICompressor comp;
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);
comp = CompressionFactory.createCompressor(kxs.np.comp_algo_server_to_client);
}
catch (IllegalArgumentException e1) {
throw new IOException("Fatal error during MAC startup!");
}
tm.changeRecvCipher(cbc, mac);
tm.changeRecvCompression(comp);
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")
|| kxs.np.kex_algo.equals("diffie-hellman-group-exchange-sha256")) {
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(kxs.hashAlgo,
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")
|| kxs.np.kex_algo.equals("ecdh-sha2-nistp256")
|| kxs.np.kex_algo.equals("ecdh-sha2-nistp384")
|| kxs.np.kex_algo.equals("ecdh-sha2-nistp521")) {
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 + ")");
}
}