001    /* DHParameterSpec.java -- Parameters for Diffie-Hellman keys.
002       Copyright (C) 2004  Free Software Foundation, Inc.
003    
004    This file is part of GNU Classpath.
005    
006    GNU Classpath is free software; you can redistribute it and/or modify
007    it under the terms of the GNU General Public License as published by
008    the Free Software Foundation; either version 2, or (at your option)
009    any later version.
010    
011    GNU Classpath is distributed in the hope that it will be useful, but
012    WITHOUT ANY WARRANTY; without even the implied warranty of
013    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014    General Public License for more details.
015    
016    You should have received a copy of the GNU General Public License
017    along with GNU Classpath; see the file COPYING.  If not, write to the
018    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019    02110-1301 USA.
020    
021    Linking this library statically or dynamically with other modules is
022    making a combined work based on this library.  Thus, the terms and
023    conditions of the GNU General Public License cover the whole
024    combination.
025    
026    As a special exception, the copyright holders of this library give you
027    permission to link this library with independent modules to produce an
028    executable, regardless of the license terms of these independent
029    modules, and to copy and distribute the resulting executable under
030    terms of your choice, provided that you also meet, for each linked
031    independent module, the terms and conditions of the license of that
032    module.  An independent module is a module which is not derived from
033    or based on this library.  If you modify this library, you may extend
034    this exception to your version of the library, but you are not
035    obligated to do so.  If you do not wish to do so, delete this
036    exception statement from your version. */
037    
038    
039    package javax.crypto.spec;
040    
041    import java.math.BigInteger;
042    import java.security.spec.AlgorithmParameterSpec;
043    
044    /**
045     * The base set of parameters necessary to perform Diffie-Hellman key
046     * exchange. Each party in the key exchange shares these parameters.
047     *
048     * <p>Each set of parameters consists of a <i>base generator</i>
049     * <code>g</code>, a <i>prime modulus</i> <code>p</code>, and an
050     * optional length, in bits, of the private exponent.
051     *
052     * <p>See <a href="http://www.rsasecurity.com/rsalabs/pkcs/pkcs-3/">PKCS
053     * #3 - Diffie-Hellman Key Agreement Standard</a> for more information.
054     *
055     * @author Casey Marshall (csm@gnu.org)
056     * @since 1.4
057     * @see javax.crypto.KeyAgreement
058     */
059    public class DHParameterSpec implements AlgorithmParameterSpec
060    {
061    
062      // Variables.
063      // ------------------------------------------------------------------------
064    
065      /** The base generator g. */
066      private BigInteger g;
067    
068      /** The prime modulus p. */
069      private BigInteger p;
070    
071      /** The length, in bits, of the private exponent. */
072      private int l;
073    
074      // Constructors.
075      // ------------------------------------------------------------------------
076    
077      /**
078       * Create a new set of Diffie-Hellman parameters.
079       *
080       * @param p The prime modulus.
081       * @param g The base generator.
082       */
083      public DHParameterSpec(BigInteger p, BigInteger g)
084      {
085        this(p, g, 0);
086      }
087    
088      /**
089       * Create a new set of Diffie-Hellman parameters.
090       *
091       * @param p The prime modulus.
092       * @param g The base generator.
093       * @param l The size of the private exponent, in bits.
094       */
095      public DHParameterSpec(BigInteger p, BigInteger g, int l)
096      {
097        this.p = p;
098        this.g = g;
099        this.l = l;
100      }
101    
102      // Instance methods.
103      // ------------------------------------------------------------------------
104    
105      /**
106       * Get the base generator, <i>g</i>.
107       *
108       * @return The base generator <i>g</i>.
109       */
110      public BigInteger getG()
111      {
112        return g;
113      }
114    
115      /**
116       * Get the length of the private exponent, in bits.
117       *
118       * @return The length of the private exponent, in bits, or 0 if this
119       *         has not been explicitly set.
120       */
121      public int getL()
122      {
123        return l;
124      }
125    
126      /**
127       * Get the prime modulus, <i>p</i>.
128       *
129       * @return The prime modulus, <i>p</i>.
130       */
131      public BigInteger getP()
132      {
133        return p;
134      }
135    }