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    1   /*
    2    * Copyright (c) 1997, 2007, Oracle and/or its affiliates. All rights reserved.
    3    * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
    4    *
    5    * This code is free software; you can redistribute it and/or modify it
    6    * under the terms of the GNU General Public License version 2 only, as
    7    * published by the Free Software Foundation.  Oracle designates this
    8    * particular file as subject to the "Classpath" exception as provided
    9    * by Oracle in the LICENSE file that accompanied this code.
   10    *
   11    * This code is distributed in the hope that it will be useful, but WITHOUT
   12    * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   13    * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   14    * version 2 for more details (a copy is included in the LICENSE file that
   15    * accompanied this code).
   16    *
   17    * You should have received a copy of the GNU General Public License version
   18    * 2 along with this work; if not, write to the Free Software Foundation,
   19    * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   20    *
   21    * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   22    * or visit www.oracle.com if you need additional information or have any
   23    * questions.
   24    */
   25   
   26   package javax.crypto.spec;
   27   
   28   import java.math.BigInteger;
   29   import java.security.spec.AlgorithmParameterSpec;
   30   
   31   /**
   32    * This class specifies the set of parameters used with the Diffie-Hellman
   33    * algorithm, as specified in PKCS #3: <i>Diffie-Hellman Key-Agreement
   34    * Standard</i>.
   35    *
   36    * <p>A central authority generates parameters and gives them to the two
   37    * entities seeking to generate a secret key. The parameters are a prime
   38    * <code>p</code>, a base <code>g</code>, and optionally the length
   39    * in bits of the private value, <code>l</code>.
   40    *
   41    * <p>It is possible that more than one instance of parameters may be
   42    * generated by a given central authority, and that there may be more than
   43    * one central authority. Indeed, each individual may be its own central
   44    * authority, with different entities having different parameters.
   45    *
   46    * <p>Note that this class does not perform any validation on specified
   47    * parameters. Thus, the specified values are returned directly even
   48    * if they are null.
   49    *
   50    * @author Jan Luehe
   51    *
   52    * @see javax.crypto.KeyAgreement
   53    * @since 1.4
   54    */
   55   public class DHParameterSpec implements AlgorithmParameterSpec {
   56   
   57       // The prime modulus
   58       private BigInteger p;
   59   
   60       // The base generator
   61       private BigInteger g;
   62   
   63       // The size in bits of the random exponent (private value) (optional)
   64       private int l;
   65   
   66       /**
   67        * Constructs a parameter set for Diffie-Hellman, using a prime modulus
   68        * <code>p</code> and a base generator <code>g</code>.
   69        *
   70        * @param p the prime modulus
   71        * @param g the base generator
   72        */
   73       public DHParameterSpec(BigInteger p, BigInteger g) {
   74           this.p = p;
   75           this.g = g;
   76           this.l = 0;
   77       }
   78   
   79       /**
   80        * Constructs a parameter set for Diffie-Hellman, using a prime modulus
   81        * <code>p</code>, a base generator <code>g</code>,
   82        * and the size in bits, <code>l</code>, of the random exponent
   83        * (private value).
   84        *
   85        * @param p the prime modulus
   86        * @param g the base generator
   87        * @param l the size in bits of the random exponent (private value)
   88        */
   89       public DHParameterSpec(BigInteger p, BigInteger g, int l) {
   90           this.p = p;
   91           this.g = g;
   92           this.l = l;
   93       }
   94   
   95       /**
   96        * Returns the prime modulus <code>p</code>.
   97        *
   98        * @return the prime modulus <code>p</code>
   99        */
  100       public BigInteger getP() {
  101           return this.p;
  102       }
  103   
  104       /**
  105        * Returns the base generator <code>g</code>.
  106        *
  107        * @return the base generator <code>g</code>
  108        */
  109       public BigInteger getG() {
  110           return this.g;
  111       }
  112   
  113       /**
  114        * Returns the size in bits, <code>l</code>, of the random exponent
  115        * (private value).
  116        *
  117        * @return the size in bits, <code>l</code>, of the random exponent
  118        * (private value), or 0 if this size has not been set
  119        */
  120       public int getL() {
  121           return this.l;
  122       }
  123   }

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