Source for gnu.java.security.jce.sig.DSSParameters

   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: }