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package javax.crypto.spec;

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

This class specifies the set of parameters used with the Diffie-Hellman
algorithm, as specified in PKCS #3: Diffie-Hellman Key-Agreement
Standard.
A central authority generates parameters and gives them to the two
entities seeking to generate a secret key. The parameters are a prime
p, a base g, and optionally the length
in bits of the private value, l.
It is possible that more than one instance of parameters may be
generated by a given central authority, and that there may be more than
one central authority. Indeed, each individual may be its own central
authority, with different entities having different parameters.
Note that this class does not perform any validation on specified
parameters. Thus, the specified values are returned directly even
if they are null.
Author:
Jan Luehe
See Also:
KeyAgreement
Since:
1.4/**
 * This class specifies the set of parameters used with the Diffie-Hellman
 * algorithm, as specified in PKCS #3: <i>Diffie-Hellman Key-Agreement
 * Standard</i>.
 *
 * <p>A central authority generates parameters and gives them to the two
 * entities seeking to generate a secret key. The parameters are a prime
 * <code>p</code>, a base <code>g</code>, and optionally the length
 * in bits of the private value, <code>l</code>.
 *
 * <p>It is possible that more than one instance of parameters may be
 * generated by a given central authority, and that there may be more than
 * one central authority. Indeed, each individual may be its own central
 * authority, with different entities having different parameters.
 *
 * <p>Note that this class does not perform any validation on specified
 * parameters. Thus, the specified values are returned directly even
 * if they are null.
 *
 * @author Jan Luehe
 *
 * @see javax.crypto.KeyAgreement
 * @since 1.4
 */
public class DHParameterSpec implements AlgorithmParameterSpec {

    // The prime modulus
    private BigInteger p;

    // The base generator
    private BigInteger g;

    // The size in bits of the random exponent (private value) (optional)
    private int l;

    
Constructs a parameter set for Diffie-Hellman, using a prime modulus
p and a base generator g.
Params:
p – the prime modulus
g – the base generator/**
     * Constructs a parameter set for Diffie-Hellman, using a prime modulus
     * <code>p</code> and a base generator <code>g</code>.
     *
     * @param p the prime modulus
     * @param g the base generator
     */
    public DHParameterSpec(BigInteger p, BigInteger g) {
        this.p = p;
        this.g = g;
        this.l = 0;
    }

    
Constructs a parameter set for Diffie-Hellman, using a prime modulus
p, a base generator g,
and the size in bits, l, of the random exponent
(private value).
Params:
p – the prime modulus
g – the base generator
l – the size in bits of the random exponent (private value)/**
     * Constructs a parameter set for Diffie-Hellman, using a prime modulus
     * <code>p</code>, a base generator <code>g</code>,
     * and the size in bits, <code>l</code>, of the random exponent
     * (private value).
     *
     * @param p the prime modulus
     * @param g the base generator
     * @param l the size in bits of the random exponent (private value)
     */
    public DHParameterSpec(BigInteger p, BigInteger g, int l) {
        this.p = p;
        this.g = g;
        this.l = l;
    }

    
Returns the prime modulus p.
Returns:
the prime modulus p/**
     * Returns the prime modulus <code>p</code>.
     *
     * @return the prime modulus <code>p</code>
     */
    public BigInteger getP() {
        return this.p;
    }

    
Returns the base generator g.
Returns:
the base generator g/**
     * Returns the base generator <code>g</code>.
     *
     * @return the base generator <code>g</code>
     */
    public BigInteger getG() {
        return this.g;
    }

    
Returns the size in bits, l, of the random exponent
(private value).
Returns:
the size in bits, l, of the random exponent
(private value), or 0 if this size has not been set/**
     * Returns the size in bits, <code>l</code>, of the random exponent
     * (private value).
     *
     * @return the size in bits, <code>l</code>, of the random exponent
     * (private value), or 0 if this size has not been set
     */
    public int getL() {
        return this.l;
    }
}