1/*
2 * Copyright (c) 2012, 2013, 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
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23 * questions.
24 */
25package java.security.spec;
26
27/**
28 * This immutable class specifies the set of parameters used for
29 * generating DSA parameters as specified in
30 * <a href="http://csrc.nist.gov/publications/fips/fips186-3/fips_186-3.pdf">FIPS 186-3 Digital Signature Standard (DSS)</a>.
31 *
32 * @see AlgorithmParameterSpec
33 *
34 * @since 1.8
35 */
36public final class DSAGenParameterSpec implements AlgorithmParameterSpec {
37
38    private final int pLen;
39    private final int qLen;
40    private final int seedLen;
41
42    /**
43     * Creates a domain parameter specification for DSA parameter
44     * generation using {@code primePLen} and {@code subprimeQLen}.
45     * The value of {@code subprimeQLen} is also used as the default
46     * length of the domain parameter seed in bits.
47     * @param primePLen the desired length of the prime P in bits.
48     * @param subprimeQLen the desired length of the sub-prime Q in bits.
49     * @exception IllegalArgumentException if {@code primePLen}
50     * or {@code subprimeQLen} is illegal per the specification of
51     * FIPS 186-3.
52     */
53    public DSAGenParameterSpec(int primePLen, int subprimeQLen) {
54        this(primePLen, subprimeQLen, subprimeQLen);
55    }
56
57    /**
58     * Creates a domain parameter specification for DSA parameter
59     * generation using {@code primePLen}, {@code subprimeQLen},
60     * and {@code seedLen}.
61     * @param primePLen the desired length of the prime P in bits.
62     * @param subprimeQLen the desired length of the sub-prime Q in bits.
63     * @param seedLen the desired length of the domain parameter seed in bits,
64     * shall be equal to or greater than {@code subprimeQLen}.
65     * @exception IllegalArgumentException if {@code primePLenLen},
66     * {@code subprimeQLen}, or {@code seedLen} is illegal per the
67     * specification of FIPS 186-3.
68     */
69    public DSAGenParameterSpec(int primePLen, int subprimeQLen, int seedLen) {
70        switch (primePLen) {
71        case 1024:
72            if (subprimeQLen != 160) {
73                throw new IllegalArgumentException
74                    ("subprimeQLen must be 160 when primePLen=1024");
75            }
76            break;
77        case 2048:
78            if (subprimeQLen != 224 && subprimeQLen != 256) {
79               throw new IllegalArgumentException
80                   ("subprimeQLen must be 224 or 256 when primePLen=2048");
81            }
82            break;
83        case 3072:
84            if (subprimeQLen != 256) {
85                throw new IllegalArgumentException
86                    ("subprimeQLen must be 256 when primePLen=3072");
87            }
88            break;
89        default:
90            throw new IllegalArgumentException
91                ("primePLen must be 1024, 2048, or 3072");
92        }
93        if (seedLen < subprimeQLen) {
94            throw new IllegalArgumentException
95                ("seedLen must be equal to or greater than subprimeQLen");
96        }
97        this.pLen = primePLen;
98        this.qLen = subprimeQLen;
99        this.seedLen = seedLen;
100    }
101
102    /**
103     * Returns the desired length of the prime P of the
104     * to-be-generated DSA domain parameters in bits.
105     * @return the length of the prime P.
106     */
107    public int getPrimePLength() {
108        return pLen;
109    }
110
111    /**
112     * Returns the desired length of the sub-prime Q of the
113     * to-be-generated DSA domain parameters in bits.
114     * @return the length of the sub-prime Q.
115     */
116    public int getSubprimeQLength() {
117        return qLen;
118    }
119
120    /**
121     * Returns the desired length of the domain parameter seed in bits.
122     * @return the length of the domain parameter seed.
123     */
124    public int getSeedLength() {
125        return seedLen;
126    }
127}
128