1 files changed, 146 insertions, 0 deletions
diff --git a/src/main/java/ch/ethz/ssh2/crypto/dh/DhExchange.java b/src/main/java/ch/ethz/ssh2/crypto/dh/DhExchange.java
new file mode 100644
index 0000000..aeb550f
--- /dev/null
+++ b/src/main/java/ch/ethz/ssh2/crypto/dh/DhExchange.java
@@ -0,0 +1,146 @@
+/*
+ * Copyright (c) 2006-2011 Christian Plattner. All rights reserved.
+ * Please refer to the LICENSE.txt for licensing details.
+ */
+package ch.ethz.ssh2.crypto.dh;
+
+import java.math.BigInteger;
+import java.security.SecureRandom;
+
+import ch.ethz.ssh2.crypto.digest.HashForSSH2Types;
+import ch.ethz.ssh2.log.Logger;
+import ch.ethz.ssh2.util.StringEncoder;
+
+/**
+ * @author Christian Plattner
+ * @version $Id: DhExchange.java 41 2011-06-02 10:36:41Z dkocher@sudo.ch $
+ */
+public class DhExchange
+{
+	private static final Logger log = Logger.getLogger(DhExchange.class);
+
+	/* Given by the standard */
+
+	static final BigInteger p1, p14;
+	static final BigInteger g;
+
+	BigInteger p;
+
+	/* Client public and private */
+
+	BigInteger e;
+	BigInteger x;
+
+	/* Server public */
+
+	BigInteger f;
+
+	/* Shared secret */
+
+	BigInteger k;
+
+	static
+	{
+		final String p1_string = "17976931348623159077083915679378745319786029604875"
+				+ "60117064444236841971802161585193689478337958649255415021805654859805036464"
+				+ "40548199239100050792877003355816639229553136239076508735759914822574862575"
+				+ "00742530207744771258955095793777842444242661733472762929938766870920560605"
+				+ "0270810842907692932019128194467627007";
+
+		final String p14_string = "FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD129"
+				+ "024E088A67CC74020BBEA63B139B22514A08798E3404DDEF9519B3CD3A431B302B0"
+				+ "A6DF25F14374FE1356D6D51C245E485B576625E7EC6F44C42E9A637ED6B0BFF5CB"
+				+ "6F406B7EDEE386BFB5A899FA5AE9F24117C4B1FE649286651ECE45B3DC2007CB8A"
+				+ "163BF0598DA48361C55D39A69163FA8FD24CF5F83655D23DCA3AD961C62F356208"
+				+ "552BB9ED529077096966D670C354E4ABC9804F1746C08CA18217C32905E462E36C"
+				+ "E3BE39E772C180E86039B2783A2EC07A28FB5C55DF06F4C52C9DE2BCBF69558171"
+				+ "83995497CEA956AE515D2261898FA051015728E5A8AACAA68FFFFFFFFFFFFFFFF";
+
+		p1 = new BigInteger(p1_string);
+		p14 = new BigInteger(p14_string, 16);
+		g = new BigInteger("2");
+	}
+
+	public DhExchange()
+	{
+	}
+
+	public void init(int group, SecureRandom rnd)
+	{
+		k = null;
+
+		if (group == 1)
+			p = p1;
+		else if (group == 14)
+			p = p14;
+		else
+			throw new IllegalArgumentException("Unknown DH group " + group);
+
+		x = new BigInteger(p.bitLength() - 1, rnd);
+
+		e = g.modPow(x, p);
+	}
+
+	/**
+	 * @return Returns the e.
+	 * @throws IllegalStateException
+	 */
+	public BigInteger getE()
+	{
+		if (e == null)
+			throw new IllegalStateException("DhDsaExchange not initialized!");
+
+		return e;
+	}
+
+	/**
+	 * @return Returns the shared secret k.
+	 * @throws IllegalStateException
+	 */
+	public BigInteger getK()
+	{
+		if (k == null)
+			throw new IllegalStateException("Shared secret not yet known, need f first!");
+
+		return k;
+	}
+
+	/**
+	 * @param f
+	 */
+	public void setF(BigInteger f)
+	{
+		if (e == null)
+			throw new IllegalStateException("DhDsaExchange not initialized!");
+
+		BigInteger zero = BigInteger.valueOf(0);
+
+		if (zero.compareTo(f) >= 0 || p.compareTo(f) <= 0)
+			throw new IllegalArgumentException("Invalid f specified!");
+
+		this.f = f;
+		this.k = f.modPow(x, p);
+	}
+
+	public byte[] calculateH(byte[] clientversion, byte[] serverversion, byte[] clientKexPayload,
+							 byte[] serverKexPayload, byte[] hostKey)
+	{
+		HashForSSH2Types hash = new HashForSSH2Types("SHA1");
+
+		if (log.isInfoEnabled())
+		{
+			log.info("Client: '" + StringEncoder.GetString(clientversion) + "'");
+		    log.info("Server: '" + StringEncoder.GetString(serverversion) + "'");
+		}
+		hash.updateByteString(clientversion);
+		hash.updateByteString(serverversion);
+		hash.updateByteString(clientKexPayload);
+		hash.updateByteString(serverKexPayload);
+		hash.updateByteString(hostKey);
+		hash.updateBigInt(e);
+		hash.updateBigInt(f);
+		hash.updateBigInt(k);
+
+		return hash.getDigest();
+	}
+}