/* DHParameterSpec.java -- Parameters for Diffie-Hellman keys.
   Copyright (C) 2004  Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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permission to link this library with independent modules to produce an
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package javax.crypto.spec;

import java.math.BigInteger;
import java.security.spec.AlgorithmParameterSpec;

/**
 * The base set of parameters necessary to perform Diffie-Hellman key
 * exchange. Each party in the key exchange shares these parameters.
 *
 * <p>Each set of parameters consists of a <i>base generator</i>
 * <code>g</code>, a <i>prime modulus</i> <code>p</code>, and an
 * optional length, in bits, of the private exponent.
 *
 * <p>See <a href="http://www.rsasecurity.com/rsalabs/pkcs/pkcs-3/">PKCS
 * #3 - Diffie-Hellman Key Agreement Standard</a> for more information.
 *
 * @author Casey Marshall (csm@gnu.org)
 * @since 1.4
 * @see javax.crypto.KeyAgreement
 */
public class DHParameterSpec implements AlgorithmParameterSpec
{

  // Variables.
  // ------------------------------------------------------------------------

  /** The base generator g. */
  private BigInteger g;

  /** The prime modulus p. */
  private BigInteger p;

  /** The length, in bits, of the private exponent. */
  private int l;

  // Constructors.
  // ------------------------------------------------------------------------

  /**
   * Create a new set of Diffie-Hellman parameters.
   *
   * @param p The prime modulus.
   * @param g The base generator.
   */
  public DHParameterSpec(BigInteger p, BigInteger g)
  {
    this(p, g, 0);
  }

  /**
   * Create a new set of Diffie-Hellman parameters.
   *
   * @param p The prime modulus.
   * @param g The base generator.
   * @param l The size of the private exponent, in bits.
   */
  public DHParameterSpec(BigInteger p, BigInteger g, int l)
  {
    this.p = p;
    this.g = g;
    this.l = l;
  }

  // Instance methods.
  // ------------------------------------------------------------------------

  /**
   * Get the base generator, <i>g</i>.
   *
   * @return The base generator <i>g</i>.
   */
  public BigInteger getG()
  {
    return g;
  }

  /**
   * Get the length of the private exponent, in bits.
   *
   * @return The length of the private exponent, in bits, or 0 if this
   *         has not been explicitly set.
   */
  public int getL()
  {
    return l;
  }

  /**
   * Get the prime modulus, <i>p</i>.
   *
   * @return The prime modulus, <i>p</i>.
   */
  public BigInteger getP()
  {
    return p;
  }
}