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

   1: /* DHParameters.java -- DH parameters DAO
   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.lang.CPStringBuilder;
  42: 
  43: import gnu.java.security.Registry;
  44: import gnu.java.security.der.DER;
  45: import gnu.java.security.der.DERReader;
  46: import gnu.java.security.der.DERValue;
  47: import gnu.java.security.der.DERWriter;
  48: import gnu.java.security.util.DerUtil;
  49: 
  50: import java.io.ByteArrayOutputStream;
  51: import java.io.IOException;
  52: import java.math.BigInteger;
  53: import java.security.AlgorithmParametersSpi;
  54: import java.security.spec.AlgorithmParameterSpec;
  55: import java.security.spec.InvalidParameterSpecException;
  56: import java.util.ArrayList;
  57: 
  58: import javax.crypto.spec.DHGenParameterSpec;
  59: import javax.crypto.spec.DHParameterSpec;
  60: 
  61: /**
  62:  * A JCE-specific Data Access Object (DAO) for DH parameters.
  63:  */
  64: public class DHParameters
  65:     extends AlgorithmParametersSpi
  66: {
  67:   /** The prime public modulus. */
  68:   private BigInteger p;
  69: 
  70:   /** The generator. */
  71:   private BigInteger g;
  72: 
  73:   /** A prime factor of p-1. */
  74:   private BigInteger q;
  75: 
  76:   /** The (private) random exponent's size (in bits). */
  77:   private int l;
  78: 
  79:   // default 0-arguments constructor
  80: 
  81:   protected void engineInit(AlgorithmParameterSpec spec)
  82:       throws InvalidParameterSpecException
  83:   {
  84:     if (! (spec instanceof DHParameterSpec))
  85:       throw new InvalidParameterSpecException("Wrong AlgorithmParameterSpec type: "
  86:                                               + spec.getClass().getName());
  87:     DHParameterSpec dhSpec = (DHParameterSpec) spec;
  88:     p = dhSpec.getP();
  89:     g = dhSpec.getG();
  90:     l = dhSpec.getL();
  91:   }
  92: 
  93:   /**
  94:    * Decodes the set of DH parameters as per RFC-2459; i.e. the DER-encoded
  95:    * form of the following ASN.1 construct:
  96:    *
  97:    * <pre>
  98:    *   DhParams ::= SEQUENCE {
  99:    *     p  INTEGER, -- odd prime, p=jq +1
 100:    *     g  INTEGER, -- generator, g
 101:    *     q  INTEGER  -- factor of p-1
 102:    *   }
 103:    * </pre>
 104:    */
 105:   protected void engineInit(byte[] params) throws IOException
 106:   {
 107:     DERReader der = new DERReader(params);
 108: 
 109:     DERValue derParams = der.read();
 110:     DerUtil.checkIsConstructed(derParams, "Wrong DH Parameters field");
 111: 
 112:     DERValue val = der.read();
 113:     DerUtil.checkIsBigInteger(val, "Wrong P field");
 114:     p = (BigInteger) val.getValue();
 115:     val = der.read();
 116:     DerUtil.checkIsBigInteger(val, "Wrong G field");
 117:     g = (BigInteger) val.getValue();
 118:     val = der.read();
 119:     DerUtil.checkIsBigInteger(val, "Wrong Q field");
 120:     q = (BigInteger) val.getValue();
 121:     l = q.bitLength();
 122:   }
 123: 
 124:   protected void engineInit(byte[] params, String format) throws IOException
 125:   {
 126:     if (format != null)
 127:       {
 128:         format = format.trim();
 129:         if (format.length() == 0)
 130:           throw new IOException("Format MUST NOT be an empty string");
 131: 
 132:         if (! format.equalsIgnoreCase(Registry.ASN1_ENCODING_SHORT_NAME))
 133:           throw new IOException("Unknown or unsupported format: " + format);
 134:       }
 135: 
 136:     engineInit(params);
 137:   }
 138: 
 139:   protected AlgorithmParameterSpec engineGetParameterSpec(Class paramSpec)
 140:       throws InvalidParameterSpecException
 141:   {
 142:     if (paramSpec.isAssignableFrom(DHParameterSpec.class))
 143:       return new DHParameterSpec(p, g, l);
 144: 
 145:     if (paramSpec.isAssignableFrom(DHGenParameterSpec.class))
 146:       return new DHGenParameterSpec(p.bitLength(), l);
 147: 
 148:     throw new InvalidParameterSpecException("Wrong AlgorithmParameterSpec type: "
 149:                                             + paramSpec.getName());
 150:   }
 151: 
 152:   /**
 153:    * Encodes the set of DH parameters as per RFC-2459; i.e. as the DER-encoded
 154:    * form of the following ASN.1 construct:
 155:    *
 156:    * <pre>
 157:    *   DhParams ::= SEQUENCE {
 158:    *     p  INTEGER, -- odd prime, p=jq +1
 159:    *     g  INTEGER, -- generator, g
 160:    *     q  INTEGER  -- factor of p-1
 161:    *   }
 162:    * </pre>
 163:    */
 164:   protected byte[] engineGetEncoded() throws IOException
 165:   {
 166:     DERValue derP = new DERValue(DER.INTEGER, p);
 167:     DERValue derG = new DERValue(DER.INTEGER, g);
 168:     DERValue derQ = new DERValue(DER.INTEGER, q);
 169: 
 170:     ArrayList params = new ArrayList(3);
 171:     params.add(derP);
 172:     params.add(derG);
 173:     params.add(derQ);
 174:     DERValue derParams = new DERValue(DER.CONSTRUCTED | DER.SEQUENCE, params);
 175: 
 176:     ByteArrayOutputStream baos = new ByteArrayOutputStream();
 177:     DERWriter.write(baos, derParams);
 178:     byte[] result = baos.toByteArray();
 179: 
 180:     return result;
 181:   }
 182: 
 183:   protected byte[] engineGetEncoded(String format) throws IOException
 184:   {
 185:     if (format != null)
 186:       {
 187:         format = format.trim();
 188:         if (format.length() == 0)
 189:           throw new IOException("Format MUST NOT be an empty string");
 190: 
 191:         if (! format.equalsIgnoreCase(Registry.ASN1_ENCODING_SHORT_NAME))
 192:           throw new IOException("Unknown or unsupported format: " + format);
 193:       }
 194: 
 195:     return engineGetEncoded();
 196:   }
 197: 
 198:   protected String engineToString()
 199:   {
 200:     CPStringBuilder sb = new CPStringBuilder("p=");
 201:     if (p == null)
 202:       sb.append("???");
 203:     else
 204:       sb.append("0x").append(p.toString(16));
 205: 
 206:     sb.append(", g=");
 207:     if (g == null)
 208:       sb.append("???");
 209:     else
 210:       sb.append("0x").append(g.toString(16));
 211: 
 212:     sb.append(", q=");
 213:     if (q == null)
 214:       sb.append("???");
 215:     else
 216:       sb.append("0x").append(q.toString(16));
 217: 
 218:     sb.append(", l=").append(l);
 219: 
 220:     return sb.toString();
 221:   }
 222: }