public void init(Session session, byte[] V_S, byte[] V_C, byte[] I_S, byte[] I_C)
throws Exception {
this.session = session;
this.V_S = V_S;
this.V_C = V_C;
this.I_S = I_S;
this.I_C = I_C;
try {
Class c = Class.forName(session.getConfig(hash));
sha = (HASH) (c.newInstance());
sha.init();
} catch (Exception e) {
System.err.println(e);
}
buf = new Buffer();
packet = new Packet(buf);
try {
Class c = Class.forName(session.getConfig("dh"));
// Since JDK8, SunJCE has lifted the keysize restrictions
// from 1024 to 2048 for DH.
preferred = max = check2048(c, max);
dh = (com.jcraft.jsch.DH) (c.newInstance());
dh.init();
} catch (Exception e) {
throw e;
}
packet.reset();
buf.putByte((byte) SSH_MSG_KEX_DH_GEX_REQUEST);
buf.putInt(min);
buf.putInt(preferred);
buf.putInt(max);
session.write(packet);
if (JSch.getLogger().isEnabled(Logger.INFO)) {
JSch.getLogger()
.log(
Logger.INFO,
"SSH_MSG_KEX_DH_GEX_REQUEST(" + min + "<" + preferred + "<" + max + ") sent");
JSch.getLogger().log(Logger.INFO, "expecting SSH_MSG_KEX_DH_GEX_GROUP");
}
state = SSH_MSG_KEX_DH_GEX_GROUP;
}
public boolean next(Buffer _buf) throws Exception {
int i, j;
switch (state) {
case SSH_MSG_KEX_DH_GEX_GROUP:
// byte SSH_MSG_KEX_DH_GEX_GROUP(31)
// mpint p, safe prime
// mpint g, generator for subgroup in GF (p)
_buf.getInt();
_buf.getByte();
j = _buf.getByte();
if (j != SSH_MSG_KEX_DH_GEX_GROUP) {
System.err.println("type: must be SSH_MSG_KEX_DH_GEX_GROUP " + j);
return false;
}
p = _buf.getMPInt();
g = _buf.getMPInt();
dh.setP(p);
dh.setG(g);
// The client responds with:
// byte SSH_MSG_KEX_DH_GEX_INIT(32)
// mpint e <- g^x mod p
// x is a random number (1 < x < (p-1)/2)
e = dh.getE();
packet.reset();
buf.putByte((byte) SSH_MSG_KEX_DH_GEX_INIT);
buf.putMPInt(e);
session.write(packet);
if (JSch.getLogger().isEnabled(Logger.INFO)) {
JSch.getLogger().log(Logger.INFO, "SSH_MSG_KEX_DH_GEX_INIT sent");
JSch.getLogger().log(Logger.INFO, "expecting SSH_MSG_KEX_DH_GEX_REPLY");
}
state = SSH_MSG_KEX_DH_GEX_REPLY;
return true;
// break;
case SSH_MSG_KEX_DH_GEX_REPLY:
// The server responds with:
// byte SSH_MSG_KEX_DH_GEX_REPLY(33)
// string server public host key and certificates (K_S)
// mpint f
// string signature of H
j = _buf.getInt();
j = _buf.getByte();
j = _buf.getByte();
if (j != SSH_MSG_KEX_DH_GEX_REPLY) {
System.err.println("type: must be SSH_MSG_KEX_DH_GEX_REPLY " + j);
return false;
}
K_S = _buf.getString();
byte[] f = _buf.getMPInt();
byte[] sig_of_H = _buf.getString();
dh.setF(f);
dh.checkRange();
K = normalize(dh.getK());
// The hash H is computed as the HASH hash of the concatenation of the
// following:
// string V_C, the client's version string (CR and NL excluded)
// string V_S, the server's version string (CR and NL excluded)
// string I_C, the payload of the client's SSH_MSG_KEXINIT
// string I_S, the payload of the server's SSH_MSG_KEXINIT
// string K_S, the host key
// uint32 min, minimal size in bits of an acceptable group
// uint32 n, preferred size in bits of the group the server should send
// uint32 max, maximal size in bits of an acceptable group
// mpint p, safe prime
// mpint g, generator for subgroup
// mpint e, exchange value sent by the client
// mpint f, exchange value sent by the server
// mpint K, the shared secret
// This value is called the exchange hash, and it is used to authenti-
// cate the key exchange.
buf.reset();
buf.putString(V_C);
buf.putString(V_S);
buf.putString(I_C);
buf.putString(I_S);
buf.putString(K_S);
buf.putInt(min);
buf.putInt(preferred);
buf.putInt(max);
buf.putMPInt(p);
buf.putMPInt(g);
buf.putMPInt(e);
buf.putMPInt(f);
buf.putMPInt(K);
byte[] foo = new byte[buf.getLength()];
buf.getByte(foo);
sha.update(foo, 0, foo.length);
H = sha.digest();
// System.err.print("H -> "); dump(H, 0, H.length);
i = 0;
j = 0;
j =
((K_S[i++] << 24) & 0xff000000)
| ((K_S[i++] << 16) & 0x00ff0000)
| ((K_S[i++] << 8) & 0x0000ff00)
| ((K_S[i++]) & 0x000000ff);
String alg = Util.byte2str(K_S, i, j);
i += j;
boolean result = verify(alg, K_S, i, sig_of_H);
state = STATE_END;
return result;
}
return false;
}
