Source for gnu.javax.crypto.key.srp6.SRPKey

   1: /* SRPKey.java --
   2:    Copyright (C) 2003, 2006 Free Software Foundation, Inc.
   3: 
   4: This file is a 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 of the License, or (at
   9: your option) 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; if not, write to the Free Software
  18: Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
  19: 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.key.srp6;
  40: 
  41: import gnu.java.security.Registry;
  42: import gnu.java.security.key.IKeyPairCodec;
  43: 
  44: import java.io.Serializable;
  45: import java.math.BigInteger;
  46: import java.security.Key;
  47: 
  48: /**
  49:  * An abstract representation of a base SRP ephemeral key.
  50:  * <p>
  51:  * This object encapsulates the two numbers:
  52:  * <ul>
  53:  * <li><b>N</b>: A large safe prime (N = 2q+1, where q is prime).</li>
  54:  * <li><b>g</b>: A generator modulo N.</li>
  55:  * </ul>
  56:  * <p>
  57:  * Note that in SRP, all arithmetic is done modulo N.
  58:  * <p>
  59:  * Reference:
  60:  * <ol>
  61:  * <li><a href="http://srp.stanford.edu/design.html">SRP Protocol Design</a><br>
  62:  * Thomas J. Wu.</li>
  63:  * </ol>
  64:  */
  65: public abstract class SRPKey
  66:     implements Key, Serializable
  67: {
  68:   /** The public, Germaine prime, shared modulus. */
  69:   protected final BigInteger N;
  70:   /** The generator. */
  71:   protected final BigInteger g;
  72: 
  73:   protected SRPKey(BigInteger N, BigInteger g)
  74:   {
  75:     super();
  76: 
  77:     this.N = N;
  78:     this.g = g;
  79:   }
  80: 
  81:   /**
  82:    * Returns the standard algorithm name for this key.
  83:    *
  84:    * @return the standard algorithm name for this key.
  85:    */
  86:   public String getAlgorithm()
  87:   {
  88:     return Registry.SRP_KPG;
  89:   }
  90: 
  91:   /** @deprecated see getEncoded(int). */
  92:   public byte[] getEncoded()
  93:   {
  94:     return getEncoded(IKeyPairCodec.RAW_FORMAT);
  95:   }
  96: 
  97:   /**
  98:    * Returns {@link Registry#RAW_ENCODING_SHORT_NAME} which is the sole format
  99:    * supported for this type of keys.
 100:    *
 101:    * @return {@link Registry#RAW_ENCODING_SHORT_NAME} ALWAYS.
 102:    */
 103:   public String getFormat()
 104:   {
 105:     return Registry.RAW_ENCODING_SHORT_NAME;
 106:   }
 107: 
 108:   /**
 109:    * Returns the public shared modulus.
 110:    *
 111:    * @return <code>N</code>.
 112:    */
 113:   public BigInteger getN()
 114:   {
 115:     return N;
 116:   }
 117: 
 118:   /**
 119:    * Returns the generator.
 120:    *
 121:    * @return <code>g</code>.
 122:    */
 123:   public BigInteger getG()
 124:   {
 125:     return g;
 126:   }
 127: 
 128:   /**
 129:    * Returns <code>true</code> if the designated object is an instance of
 130:    * <code>SRPKey</code> and has the same SRP parameter values as this one.
 131:    *
 132:    * @param obj the other non-null SRP key to compare to.
 133:    * @return <code>true</code> if the designated object is of the same type
 134:    *         and value as this one.
 135:    */
 136:   public boolean equals(Object obj)
 137:   {
 138:     if (obj == null)
 139:       return false;
 140:     if (! (obj instanceof SRPKey))
 141:       return false;
 142:     SRPKey that = (SRPKey) obj;
 143:     return N.equals(that.getN()) && g.equals(that.getG());
 144:   }
 145: 
 146:   public abstract byte[] getEncoded(int format);
 147: }