libjava/classpath/gnu/javax/crypto/jce/sig/DHParametersGenerator.java

   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 }