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
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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
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24 */
25
26package javax.crypto.spec;
27
28import java.math.BigInteger;
29import 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 */
55public 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}
124