Source for gnu.javax.crypto.key.srp6.SRP6SaslClient

   1: /* SRP6SaslClient.java --
   2:    Copyright (C) 2003, 2006 Free Software Foundation, Inc.
   3: 
   4: This file is a part of GNU Classpath.
   5: 
   6: GNU Classpath is free software; you can redistribute it and/or modify
   7: it under the terms of the GNU General Public License as published by
   8: the Free Software Foundation; either version 2 of the License, or (at
   9: your option) any later version.
  10: 
  11: GNU Classpath is distributed in the hope that it will be useful, but
  12: WITHOUT ANY WARRANTY; without even the implied warranty of
  13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14: General Public License for more details.
  15: 
  16: You should have received a copy of the GNU General Public License
  17: along with GNU Classpath; if not, write to the Free Software
  18: Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
  19: USA
  20: 
  21: Linking this library statically or dynamically with other modules is
  22: making a combined work based on this library.  Thus, the terms and
  23: conditions of the GNU General Public License cover the whole
  24: combination.
  25: 
  26: As a special exception, the copyright holders of this library give you
  27: permission to link this library with independent modules to produce an
  28: executable, regardless of the license terms of these independent
  29: modules, and to copy and distribute the resulting executable under
  30: terms of your choice, provided that you also meet, for each linked
  31: independent module, the terms and conditions of the license of that
  32: module.  An independent module is a module which is not derived from
  33: or based on this library.  If you modify this library, you may extend
  34: this exception to your version of the library, but you are not
  35: obligated to do so.  If you do not wish to do so, delete this
  36: exception statement from your version.  */
  37: 
  38: 
  39: package gnu.javax.crypto.key.srp6;
  40: 
  41: import gnu.java.security.hash.IMessageDigest;
  42: import gnu.java.security.util.Util;
  43: 
  44: import gnu.javax.crypto.key.KeyAgreementException;
  45: import gnu.javax.crypto.key.IncomingMessage;
  46: import gnu.javax.crypto.key.OutgoingMessage;
  47: 
  48: import java.math.BigInteger;
  49: 
  50: /**
  51:  * A variation of the SRP-6 protocol as used in the SASL-SRP mechanism, for the
  52:  * User (client side).
  53:  * <p>
  54:  * In this alternative, the exchange goes as follows:
  55:  *
  56:  * <pre>
  57:  *     C -&gt; S:  I                      (identifies self)
  58:  *     S -&gt; C:  N, g, s, B = 3v + g&circ;b  (sends salt, b = random number)
  59:  *     C -&gt; S:  A = g&circ;a                (a = random number)
  60:  * </pre>
  61:  *
  62:  * <p>
  63:  * All elements are computed the same way as in the standard version.
  64:  * <p>
  65:  * Reference:
  66:  * <ol>
  67:  * <li><a
  68:  * href="http://www.ietf.org/internet-drafts/draft-burdis-cat-srp-sasl-09.txt">
  69:  * Secure Remote Password Authentication Mechanism</a><br>
  70:  * K. Burdis, R. Naffah.</li>
  71:  * <li><a href="http://srp.stanford.edu/design.html">SRP Protocol Design</a><br>
  72:  * Thomas J. Wu.</li>
  73:  * </ol>
  74:  */
  75: public class SRP6SaslClient
  76:     extends SRP6TLSClient
  77: {
  78:   // default 0-arguments constructor
  79: 
  80:   protected OutgoingMessage computeSharedSecret(final IncomingMessage in)
  81:       throws KeyAgreementException
  82:   {
  83:     final OutgoingMessage result = super.computeSharedSecret(in);
  84:     final byte[] sBytes = Util.trim(K);
  85:     final IMessageDigest hash = srp.newDigest();
  86:     hash.update(sBytes, 0, sBytes.length);
  87:     K = new BigInteger(1, hash.digest());
  88:     return result;
  89:   }
  90: }