libjava/classpath/gnu/java/security/jce/sig/DSSParameters.java

   1 /* DSSParameters.java -- DSS 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.java.security.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.DSAParameterSpec;
  56 import java.security.spec.InvalidParameterSpecException;
  57 import java.util.ArrayList;
  58
  59 /**
  60  * A JCE-specific Data Access Object (DAO) for DSS parameters.
  61  */
  62 public class DSSParameters
  63     extends AlgorithmParametersSpi
  64 {
  65   /**
  66    * A prime modulus, where <code>2<sup>L-1</sup> &lt; p &lt; 2<sup>L</sup></code>
  67    * for <code>512 &lt;= L &lt;= 1024</code> and <code>L</code> a multiple of
  68    * <code>64</code>.
  69    */
  70   private BigInteger p;
  71
  72   /**
  73    * A prime divisor of <code>p - 1</code>, where <code>2<sup>159</sup> &lt; q
  74    * &lt; 2<sup>160</sup></code>.
  75    */
  76   private BigInteger q;
  77
  78   /**
  79    * <code>g = h<sup>(p-1)</sup>/q mod p</code>, where <code>h</code> is any
  80    * integer with <code>1 &lt; h &lt; p - 1</code> such that <code>h<sup>
  81    * (p-1)</sup>/q mod p > 1</code> (<code>g</code> has order <code>q mod p
  82    * </code>).
  83    */
  84   private BigInteger g;
  85
  86   // default 0-arguments constructor
  87
  88   protected void engineInit(AlgorithmParameterSpec spec)
  89       throws InvalidParameterSpecException
  90   {
  91     if (! (spec instanceof DSAParameterSpec))
  92       throw new InvalidParameterSpecException("Wrong AlgorithmParameterSpec type: "
  93                                               + spec.getClass().getName());
  94     DSAParameterSpec dsaSpec = (DSAParameterSpec) spec;
  95     p = dsaSpec.getP();
  96     q = dsaSpec.getQ();
  97     g = dsaSpec.getG();
  98   }
  99
 100   /**
 101    * Decodes the set of DSS parameters as per RFC-2459; i.e. the DER-encoded
 102    * form of the following ASN.1 construct:
 103    *
 104    * <pre>
 105    *   DssParams ::= SEQUENCE {
 106    *     p   INTEGER,
 107    *     q   INTEGER,
 108    *     g   INTEGER
 109    *   }
 110    * </pre>
 111    */
 112   protected void engineInit(byte[] params) throws IOException
 113   {
 114     DERReader der = new DERReader(params);
 115
 116     DERValue derParams = der.read();
 117     DerUtil.checkIsConstructed(derParams, "Wrong DSS Parameters field");
 118
 119     DERValue val = der.read();
 120     DerUtil.checkIsBigInteger(val, "Wrong P field");
 121     p = (BigInteger) val.getValue();
 122     val = der.read();
 123     DerUtil.checkIsBigInteger(val, "Wrong Q field");
 124     q = (BigInteger) val.getValue();
 125     val = der.read();
 126     DerUtil.checkIsBigInteger(val, "Wrong G field");
 127     g = (BigInteger) val.getValue();
 128   }
 129
 130   protected void engineInit(byte[] params, String format) throws IOException
 131   {
 132     if (format != null)
 133       {
 134         format = format.trim();
 135         if (format.length() == 0)
 136           throw new IOException("Format MUST NOT be an empty string");
 137
 138         if (! format.equalsIgnoreCase(Registry.ASN1_ENCODING_SHORT_NAME))
 139           throw new IOException("Unknown or unsupported format: " + format);
 140       }
 141     engineInit(params);
 142   }
 143
 144   protected AlgorithmParameterSpec engineGetParameterSpec(Class paramSpec)
 145       throws InvalidParameterSpecException
 146   {
 147     if (! paramSpec.isAssignableFrom(DSAParameterSpec.class))
 148       throw new InvalidParameterSpecException("Wrong AlgorithmParameterSpec type: "
 149                                               + paramSpec.getName());
 150     return new DSAParameterSpec(p, q, g);
 151   }
 152
 153   /**
 154    * Encodes the set of DSS parameters as per RFC-2459; i.e. as the DER-encoded
 155    * form of the following ASN.1 construct:
 156    *
 157    * <pre>
 158    *   DssParams ::= SEQUENCE {
 159    *     p   INTEGER,
 160    *     q   INTEGER,
 161    *     g   INTEGER
 162    *   }
 163    * </pre>
 164    */
 165   protected byte[] engineGetEncoded() throws IOException
 166   {
 167     DERValue derP = new DERValue(DER.INTEGER, p);
 168     DERValue derQ = new DERValue(DER.INTEGER, q);
 169     DERValue derG = new DERValue(DER.INTEGER, g);
 170
 171     ArrayList params = new ArrayList(3);
 172     params.add(derP);
 173     params.add(derQ);
 174     params.add(derG);
 175     DERValue derParams = new DERValue(DER.CONSTRUCTED | DER.SEQUENCE, params);
 176
 177     ByteArrayOutputStream baos = new ByteArrayOutputStream();
 178     DERWriter.write(baos, derParams);
 179     byte[] result = baos.toByteArray();
 180
 181     return result;
 182   }
 183
 184   protected byte[] engineGetEncoded(String format) throws IOException
 185   {
 186     if (format != null)
 187       {
 188         format = format.trim();
 189         if (format.length() == 0)
 190           throw new IOException("Format MUST NOT be an empty string");
 191
 192         if (! format.equalsIgnoreCase(Registry.ASN1_ENCODING_SHORT_NAME))
 193           throw new IOException("Unknown or unsupported format: " + format);
 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(", q=");
 207     if (q == null)
 208       sb.append("???");
 209     else
 210       sb.append("0x").append(q.toString(16));
 211
 212     sb.append(", g=");
 213     if (g == null)
 214       sb.append("???");
 215     else
 216       sb.append("0x").append(g.toString(16));
 217
 218     return sb.toString();
 219   }
 220 }