Source for gnu.javax.crypto.jce.sig.DHParametersGenerator

   1: /* DHParametersGenerator.java -- JCE Adapter for a generator of DH parameters
   2:    Copyright (C) 2006 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.javax.crypto.jce.sig;
  40: 
  41: import gnu.java.security.Registry;
  42: import gnu.javax.crypto.jce.GnuCrypto;
  43: import gnu.javax.crypto.key.dh.GnuDHKeyPairGenerator;
  44: import gnu.javax.crypto.key.dh.RFC2631;
  45: 
  46: import java.math.BigInteger;
  47: import java.security.AlgorithmParameterGeneratorSpi;
  48: import java.security.AlgorithmParameters;
  49: import java.security.InvalidAlgorithmParameterException;
  50: import java.security.InvalidParameterException;
  51: import java.security.NoSuchAlgorithmException;
  52: import java.security.Provider;
  53: import java.security.SecureRandom;
  54: import java.security.spec.AlgorithmParameterSpec;
  55: import java.security.spec.InvalidParameterSpecException;
  56: 
  57: import javax.crypto.spec.DHGenParameterSpec;
  58: import javax.crypto.spec.DHParameterSpec;
  59: 
  60: /**
  61:  * A JCE Adapter for a generator of DH parameters.
  62:  */
  63: public class DHParametersGenerator
  64:     extends AlgorithmParameterGeneratorSpi
  65: {
  66:   private static final Provider GNU_CRYPTO = new GnuCrypto();
  67: 
  68:   /** Size of the prime (public) modulus in bits. */
  69:   private int modulusSize = -1;
  70: 
  71:   /** Size of the prime (private) modulus in bits. */
  72:   private int exponentSize = -1;
  73: 
  74:   /** User specified source of randomness. */
  75:   private SecureRandom rnd;
  76: 
  77:   /** Our concrete DH parameters generator. */
  78:   private RFC2631 rfc2631;
  79: 
  80: 
  81:   protected void engineInit(int size, SecureRandom random)
  82:   {
  83:     if ((size % 256) != 0 || size < GnuDHKeyPairGenerator.DEFAULT_PRIME_SIZE)
  84:       throw new InvalidParameterException("Prime modulus (p) size (in bits) "
  85:                                           + "MUST be a multiple of 256, and "
  86:                                           + "greater than or equal to 1024");
  87:     this.modulusSize = size;
  88:     this.rnd = random;
  89:   }
  90: 
  91:   protected void engineInit(AlgorithmParameterSpec spec, SecureRandom random)
  92:       throws InvalidAlgorithmParameterException
  93:   {
  94:     if (spec instanceof DHParameterSpec)
  95:       {
  96:         DHParameterSpec dhSpec = (DHParameterSpec) spec;
  97:         BigInteger p = dhSpec.getP();
  98:         int size = p.bitLength();
  99:         this.engineInit(size, random);
 100:       }
 101:     else if (spec instanceof DHGenParameterSpec)
 102:       {
 103:         DHGenParameterSpec dhSpec = (DHGenParameterSpec) spec;
 104:         int size = dhSpec.getPrimeSize();
 105:         this.engineInit(size, random);
 106:         exponentSize = dhSpec.getExponentSize();
 107: 
 108:         if ((exponentSize % 8) != 0
 109:             || exponentSize < GnuDHKeyPairGenerator.DEFAULT_EXPONENT_SIZE)
 110:           throw new InvalidParameterException("Random exponent size (in bits) "
 111:                                               + "MUST be a multiple of 8, and "
 112:                                               + "greater than or equal to "
 113:                                               + GnuDHKeyPairGenerator.DEFAULT_EXPONENT_SIZE);
 114:         if (exponentSize > modulusSize)
 115:           throw new InvalidParameterException("Random exponent size (in bits) "
 116:                                               + "MUST be less than that of the "
 117:                                               + "public prime modulus (p)");
 118:       }
 119: 
 120:     throw new InvalidAlgorithmParameterException("Wrong AlgorithmParameterSpec type: "
 121:                                                  + spec.getClass().getName());
 122:   }
 123: 
 124:   protected AlgorithmParameters engineGenerateParameters()
 125:   {
 126:     if (modulusSize < 1)
 127:       modulusSize = GnuDHKeyPairGenerator.DEFAULT_PRIME_SIZE;
 128: 
 129:     if (exponentSize < 1)
 130:       exponentSize = GnuDHKeyPairGenerator.DEFAULT_EXPONENT_SIZE;
 131: 
 132:     rfc2631 = new RFC2631(exponentSize, modulusSize, rnd);
 133:     BigInteger[] params = rfc2631.generateParameters();
 134:     BigInteger p = params[RFC2631.DH_PARAMS_P];
 135:     BigInteger g = params[RFC2631.DH_PARAMS_G];
 136:     int l = params[RFC2631.DH_PARAMS_Q].bitLength();
 137:     DHParameterSpec spec = new DHParameterSpec(p, g, l);
 138:     AlgorithmParameters result = null;
 139:     try
 140:       {
 141:         result = AlgorithmParameters.getInstance(Registry.DH_KPG, GNU_CRYPTO);
 142:         result.init(spec);
 143:       }
 144:     catch (NoSuchAlgorithmException ignore)
 145:       {
 146:       }
 147:     catch (InvalidParameterSpecException ignore)
 148:       {
 149:       }
 150:     return result;
 151:   }
 152: }