Source for gnu.java.security.provider.DiffieHellmanKeyPairGeneratorImpl

   1: /* DiffieHellmanKeyPairGeneratorImpl.java --
   2:    Copyright (C) 2005 Free Software Foundation, Inc.
   3: 
   4: This file is 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, or (at your option)
   9: 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; see the file COPYING.  If not, write to the
  18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19: 02110-1301 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.java.security.provider;
  40: 
  41: import gnu.javax.crypto.GnuDHPrivateKey;
  42: 
  43: import java.math.BigInteger;
  44: 
  45: import java.security.KeyPair;
  46: import java.security.KeyPairGeneratorSpi;
  47: import java.security.SecureRandom;
  48: import java.security.spec.AlgorithmParameterSpec;
  49: 
  50: import javax.crypto.spec.DHParameterSpec;
  51: 
  52: public class DiffieHellmanKeyPairGeneratorImpl extends KeyPairGeneratorSpi
  53: {
  54:   private SecureRandom random;
  55:   private DHParameterSpec params;
  56: 
  57:   public KeyPair generateKeyPair ()
  58:   {
  59:     if (params == null || random == null)
  60:       throw new IllegalStateException ("not initialized");
  61:     byte[] buf = new byte[(params.getP ().bitLength() >>> 3)];
  62:     random.nextBytes (buf);
  63:     BigInteger x = new BigInteger (1, buf);
  64:     BigInteger y = params.getG ().modPow (x, params.getP ());
  65:     GnuDHPublicKey pub = new GnuDHPublicKey (params, y, null);
  66:     GnuDHPrivateKey priv = new GnuDHPrivateKey (x, params);
  67: 
  68:     return new KeyPair (pub, priv);
  69:   }
  70: 
  71:   public void initialize (final int keysize, final SecureRandom random)
  72:   {
  73:     throw new UnsupportedOperationException ("key generation without parameters not supported");
  74:   }
  75: 
  76:   public void initialize (final AlgorithmParameterSpec params,
  77:                           final SecureRandom random)
  78:   {
  79:     if (!(params instanceof DHParameterSpec))
  80:       throw new IllegalArgumentException ("expecting Diffie-Hellman parameters");
  81:     this.params = (DHParameterSpec) params;
  82:     this.random = random;
  83:     if (this.random == null)
  84:       this.random = new SecureRandom ();
  85:   }
  86: }