Logo Search packages:      
Sourcecode: jenkins-trilead-ssh2 version File versions  Download package

DhExchange.java

package com.trilead.ssh2.crypto.dh;

import java.math.BigInteger;
import java.security.SecureRandom;

import com.trilead.ssh2.crypto.digest.HashForSSH2Types;
import com.trilead.ssh2.log.Logger;


/**
 * DhExchange.
 * 
 * @author Christian Plattner, plattner@trilead.com
 * @version $Id: DhExchange.java,v 1.1 2007/10/15 12:49:57 cplattne Exp $
 */
00017 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
       */
00087       public BigInteger getE()
      {
            if (e == null)
                  throw new IllegalStateException("DhDsaExchange not initialized!");

            return e;
      }

      /**
       * @return Returns the shared secret k.
       * @throws IllegalStateException
       */
00099       public BigInteger getK()
      {
            if (k == null)
                  throw new IllegalStateException("Shared secret not yet known, need f first!");

            return k;
      }

      /**
       * @param f
       */
00110       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.isEnabled())
            {
                  log.log(90, "Client: '" + new String(clientversion) + "'");
                  log.log(90, "Server: '" + new String(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();
      }
}

Generated by  Doxygen 1.6.0   Back to index