Trilead ssh2 fix big integer removes leading zero (#178)

* Update TimeoutService.java

interrupt hanging timeoutservice threads

* Update TimeoutService.java

* Update TimeoutService.java

* Update Connection.java

* Update Connection.java

* Update TimeoutService.java

* Update TimeoutService.java

* Update Connection.java

* fix BigInteger

---------

Co-authored-by: mikael petterson <[email protected]>

.gitignore

@@ -14,3 +14,12 @@ target/
 .metadata
 .loadpath
 bin/
+
+#Netbeans files
+nbproject/private/
+build/
+nbbuild/
+dist/
+nbdist/
+nbactions.xml
+nb-configuration.xml

src/com/trilead/ssh2/packets/PacketKexDHReply.java

@@ -2,7 +2,6 @@
 
 import java.io.IOException;
 
-import java.math.BigInteger;
 
 /**
  * PacketKexDHReply.
@@ -15,7 +14,7 @@ public class PacketKexDHReply
 	byte[] payload;
 
 	byte[] hostKey;
-	BigInteger f;
+        byte [] publicKey;
 	byte[] signature;
 
 	public PacketKexDHReply(byte payload[], int off, int len) throws IOException
@@ -32,15 +31,16 @@ public PacketKexDHReply(byte payload[], int off, int len) throws IOException
 					+ packet_type + ")");
 
 		hostKey = tr.readByteString();
-		f = tr.readMPINT();
+		publicKey = tr.readByteString();
 		signature = tr.readByteString();
 
 		if (tr.remain() != 0) throw new IOException("PADDING IN SSH_MSG_KEXDH_REPLY!");
 	}
 
-	public BigInteger getF()
+	public byte[] getF()
 	{
-		return f;
+		return publicKey;
+
 	}
 
 	public byte[] getHostKey()

src/com/trilead/ssh2/transport/KexManager.java

@@ -658,7 +658,7 @@ public synchronized void handleMessage(byte[] msg, int msglen) throws IOExceptio
 						throw new IOException("The server hostkey was not accepted by the verifier callback");
 				}
 
-				kxs.dhx.setF(dhr.getF().toByteArray());
+				kxs.dhx.setF(dhr.getF());
 
 				try
 				{

test/com/trilead/ssh2/crypto/dh/Curve25519ExchangeTest.java

@@ -1,14 +1,19 @@
 package com.trilead.ssh2.crypto.dh;
 
 import com.google.crypto.tink.subtle.X25519;
+import com.trilead.ssh2.packets.PacketKexDHReply;
+import java.io.IOException;
 
 import org.junit.Test;
 
 import java.math.BigInteger;
+import java.security.InvalidKeyException;
 
 import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotEquals;
 import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.fail;
 
 /**
  * Created by Kenny Root on 1/23/16.
@@ -76,4 +81,65 @@ public void knownValues_Bob() throws Exception {
 		ex.setF(ALICE_PUBLIC);
 		assertEquals(KNOWN_SHARED_SECRET_BI, ex.sharedSecret);
 	}
+
+        @Test
+	public void testBigIntegerRemovesLeadingZero() throws Exception {
+
+               BigInteger bigIntegerWithoutLeadingZero = new BigInteger(1, toByteArray("4a5d9d5ba4ce2de1728e3bf480350f25e07e21c947d19e3376f09b3c1e161742"));
+
+               BigInteger bigIntegerWithLeadingZero = new BigInteger(1, toByteArray("015d9d5ba4ce2de1728e3bf480350f25e07e21c947d19e3376f09b3c1e161742"));
+               //The key with same length does not become the same when using BigInteger when a key has leading zeros. This is because BigInteger has stripLeadingZeroBytes method.
+               assertNotEquals(Integer.valueOf(bigIntegerWithoutLeadingZero.bitLength()),Integer.valueOf(bigIntegerWithLeadingZero.bitLength()));
+
+
+
+	}
+
+
+    @Test
+    public void testKeyWithLeadingZeros() throws InvalidKeyException{
+
+        //When the message contains leading 0 then the BigInteger class
+        //will remove the leading zero since it has a function to do so internally.
+        Curve25519Exchange curve25519Exchange = new Curve25519Exchange(ALICE_PRIVATE);
+
+        //public Diffie-Hellman key and other parameters in message. This one has
+        //leading zero.0, 0, 0, 2, 2, 2, 2, 2
+        byte[] msg = new byte[]{
+            31,
+
+            0, 0, 0, 32,
+            1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1,
+
+            0, 0, 0, 32,
+            0, 0, 0, 2, 2, 2, 2, 2,
+            2, 2, 2, 2, 2, 2, 2, 2,
+            2, 2, 2, 2, 2, 2, 2, 2,
+            2, 2, 2, 2, 2, 2, 2, 2,
+
+            0, 0, 0, 32,
+            3, 3, 3, 3, 3, 3, 3, 3,
+            3, 3, 3, 3, 3, 3, 3, 3,
+            3, 3, 3, 3, 3, 3, 3, 3,
+            3, 3, 3, 3, 3, 3, 3, 3
+            };
+        PacketKexDHReply dhr = null;
+
+        try {
+            dhr = new PacketKexDHReply(msg, 0, msg.length);
+        } catch (IOException ioex) {
+             fail("We should not get exception when creating the PacketKexDHReply "+ioex.getMessage());
+        }
+        try {
+            curve25519Exchange.setF(dhr.getF());
+        } catch (IOException ioex) {
+           fail("We should not get exception while setting curve key "+ioex.getMessage());
+
+        }
+    }
+
 }
+