1adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project/*
2adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project *  Licensed to the Apache Software Foundation (ASF) under one or more
3adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project *  contributor license agreements.  See the NOTICE file distributed with
4adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project *  this work for additional information regarding copyright ownership.
5adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project *  The ASF licenses this file to You under the Apache License, Version 2.0
6adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project *  (the "License"); you may not use this file except in compliance with
7adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project *  the License.  You may obtain a copy of the License at
8adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project *
9adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project *     http://www.apache.org/licenses/LICENSE-2.0
10adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project *
11adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project *  Unless required by applicable law or agreed to in writing, software
12adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project *  distributed under the License is distributed on an "AS IS" BASIS,
13adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project *  See the License for the specific language governing permissions and
15adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project *  limitations under the License.
16adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project */
17adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project
18adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Projectpackage javax.crypto.spec;
19adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project
20adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Projectimport java.security.InvalidKeyException;
21adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Projectimport java.security.spec.KeySpec;
22adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project
23adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project/**
24adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * The key specification for a DES key.
25adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project */
26adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Projectpublic class DESKeySpec implements KeySpec {
27adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project
28adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project    /**
29adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     * The length of a DES key in bytes.
30adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     */
31adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project    public static final int DES_KEY_LEN = 8;
32adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project
33adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project    private final byte[] key;
34adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project
35adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project    // DES weak and semi-weak keys
36adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project    // Got from:
37adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project    // FIP PUB 74
38adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project    // FEDERAL INFORMATION PROCESSING STANDARDS PUBLICATION 1981
39f33eae7e84eb6d3b0f4e86b59605bb3de73009f3Elliott Hughes    // GUIDELINES FOR IMPLEMENTING AND USING THE NBS DATA ENCRYPTION STANDARD
40adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project    // http://www.dice.ucl.ac.be/crypto/standards/fips/fip74/fip74-1.pdf
41adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project    private static final byte[][] SEMIWEAKS = {
42adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                {(byte) 0xE0, (byte) 0x01, (byte) 0xE0, (byte) 0x01,
43adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                 (byte) 0xF1, (byte) 0x01, (byte) 0xF1, (byte) 0x01},
44adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project
45adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                {(byte) 0x01, (byte) 0xE0, (byte) 0x01, (byte) 0xE0,
46adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                 (byte) 0x01, (byte) 0xF1, (byte) 0x01, (byte) 0xF1},
47adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project
48adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                {(byte) 0xFE, (byte) 0x1F, (byte) 0xFE, (byte) 0x1F,
49adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                 (byte) 0xFE, (byte) 0x0E, (byte) 0xFE, (byte) 0x0E},
50adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project
51adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                {(byte) 0x1F, (byte) 0xFE, (byte) 0x1F, (byte) 0xFE,
52adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                 (byte) 0x0E, (byte) 0xFE, (byte) 0x0E, (byte) 0xFE},
53adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project
54adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                {(byte) 0xE0, (byte) 0x1F, (byte) 0xE0, (byte) 0x1F,
55adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                 (byte) 0xF1, (byte) 0x0E, (byte) 0xF1, (byte) 0x0E},
56adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project
57adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                {(byte) 0x1F, (byte) 0xE0, (byte) 0x1F, (byte) 0xE0,
58adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                 (byte) 0x0E, (byte) 0xF1, (byte) 0x0E, (byte) 0xF1},
59adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project
60adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                {(byte) 0x01, (byte) 0xFE, (byte) 0x01, (byte) 0xFE,
61adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                 (byte) 0x01, (byte) 0xFE, (byte) 0x01, (byte) 0xFE},
62adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project
63adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                {(byte) 0xFE, (byte) 0x01, (byte) 0xFE, (byte) 0x01,
64adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                 (byte) 0xFE, (byte) 0x01, (byte) 0xFE, (byte) 0x01},
65adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project
66adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                {(byte) 0x01, (byte) 0x1F, (byte) 0x01, (byte) 0x1F,
67adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                 (byte) 0x01, (byte) 0x0E, (byte) 0x01, (byte) 0x0E},
68adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project
69adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                {(byte) 0x1F, (byte) 0x01, (byte) 0x1F, (byte) 0x01,
70adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                 (byte) 0x0E, (byte) 0x01, (byte) 0x0E, (byte) 0x01},
71adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project
72adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                {(byte) 0xE0, (byte) 0xFE, (byte) 0xE0, (byte) 0xFE,
73adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                 (byte) 0xF1, (byte) 0xFE, (byte) 0xF1, (byte) 0xFE},
74adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project
75adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                {(byte) 0xFE, (byte) 0xE0, (byte) 0xFE, (byte) 0xE0,
76adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                 (byte) 0xFE, (byte) 0xF1, (byte) 0xFE, (byte) 0xF1},
77adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project
78f33eae7e84eb6d3b0f4e86b59605bb3de73009f3Elliott Hughes                {(byte) 0x01, (byte) 0x01, (byte) 0x01, (byte) 0x01,
79adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                 (byte) 0x01, (byte) 0x01, (byte) 0x01, (byte) 0x01},
80adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project
81adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                {(byte) 0xFE, (byte) 0xFE, (byte) 0xFE, (byte) 0xFE,
82adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                 (byte) 0xFE, (byte) 0xFE, (byte) 0xFE, (byte) 0xFE},
83adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project
84adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                {(byte) 0xE0, (byte) 0xE0, (byte) 0xE0, (byte) 0xE0,
85adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                 (byte) 0xF1, (byte) 0xF1, (byte) 0xF1, (byte) 0xF1},
86adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project
87adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                {(byte) 0x1F, (byte) 0x1F, (byte) 0x1F, (byte) 0x1F,
88adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                 (byte) 0x0E, (byte) 0x0E, (byte) 0x0E, (byte) 0x0E},
89adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project
90adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                };
91adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project
92adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project    /**
93adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     * Creates a new <code>DESKeySpec</code> from the first 8 bytes of the
94adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     * specified key data.
95ce9ec01c0b6da3f3ba01e9c81cc3e5a461aabfb6Jesse Wilson     *
96adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     * @param key
97adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     *            the key data.
98adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     * @throws InvalidKeyException
99adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     *             if the length of the specified key data is less than 8.
100adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     */
101adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project    public DESKeySpec(byte[] key) throws InvalidKeyException {
102adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project        this(key, 0);
103adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project    }
104adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project
105adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project    /**
106adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     * Creates a new <code>DESKeySpec</code> from the first 8 bytes of the
107adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     * specified key data starting at <code>offset</code>.
108ce9ec01c0b6da3f3ba01e9c81cc3e5a461aabfb6Jesse Wilson     *
109adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     * @param key
110adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     *            the key data
111adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     * @param offset
112adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     *            the offset to start at.
113adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     * @throws InvalidKeyException
114adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     *             if the length of the specified key data starting at offset is
115adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     *             less than 8.
116adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     */
11780a7fbab52b96c9fd47c72f8987d1babe2cd001dElliott Hughes    public DESKeySpec(byte[] key, int offset) throws InvalidKeyException {
118adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project        if (key == null) {
11980a7fbab52b96c9fd47c72f8987d1babe2cd001dElliott Hughes            throw new NullPointerException("key == null");
120adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project        }
121adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project        if (key.length - offset < DES_KEY_LEN) {
12280a7fbab52b96c9fd47c72f8987d1babe2cd001dElliott Hughes            throw new InvalidKeyException("key too short");
123adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project        }
124adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project        this.key = new byte[DES_KEY_LEN];
125adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project        System.arraycopy(key, offset, this.key, 0, DES_KEY_LEN);
126adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project    }
127adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project
128adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project    /**
129adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     * Returns a copy of the key.
130ce9ec01c0b6da3f3ba01e9c81cc3e5a461aabfb6Jesse Wilson     *
131adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     * @return a copy of the key.
132adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     */
133adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project    public byte[] getKey() {
134adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project        byte[] result = new byte[DES_KEY_LEN];
135adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project        System.arraycopy(this.key, 0, result, 0, DES_KEY_LEN);
136adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project        return result;
137adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project    }
138adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project
139adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project    /**
140adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     * Returns whether the specified key data starting at <code>offset</code> is
141adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     * <i>parity-adjusted</i>.
142ce9ec01c0b6da3f3ba01e9c81cc3e5a461aabfb6Jesse Wilson     *
143adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     * @param key
144adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     *            the key data.
145adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     * @param offset
146adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     *            the offset to start checking at.
147adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     * @return {@code true} if the specified key data is parity-adjusted,
148adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     *            {@code false} otherwise.
149adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     * @throws InvalidKeyException
150adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     *             if the length of the key data starting at offset is less than
151adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     *             8, or the key is null.
152adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     */
15380a7fbab52b96c9fd47c72f8987d1babe2cd001dElliott Hughes    public static boolean isParityAdjusted(byte[] key, int offset) throws InvalidKeyException {
154adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project        if (key == null) {
15580a7fbab52b96c9fd47c72f8987d1babe2cd001dElliott Hughes            throw new InvalidKeyException("key == null");
156adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project        }
157adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project        if (key.length - offset < DES_KEY_LEN) {
15880a7fbab52b96c9fd47c72f8987d1babe2cd001dElliott Hughes            throw new InvalidKeyException("key too short");
159adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project        }
160adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project
161adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project        int byteKey = 0;
162adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project
163adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project        for (int i = offset; i < DES_KEY_LEN; i++) {
164adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project            byteKey = key[i];
165adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project
166adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project            byteKey ^= byteKey >> 1;
167adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project            byteKey ^= byteKey >> 2;
168adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project            byteKey ^= byteKey >> 4;
169adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project
170adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project            if ((byteKey & 1) == 0) {
171adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                return false;
172adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project            }
173adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project        }
174adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project        return true;
175adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project    }
176adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project
177adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project    /**
178adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     * Returns whether the specified key data starting at <code>offset</code> is
179adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     * weak or semi-weak.
180ce9ec01c0b6da3f3ba01e9c81cc3e5a461aabfb6Jesse Wilson     *
181adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     * @param key
182adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     *            the key data.
183adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     * @param offset
184adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     *            the offset to start checking at.
185adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     * @return {@code true} if the specified key data is weak or semi-weak.
186adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     * @throws InvalidKeyException
187adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     *             if the length of the key data starting at offset is less than
188adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     *             8, or it is null.
189adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project     */
19080a7fbab52b96c9fd47c72f8987d1babe2cd001dElliott Hughes    public static boolean isWeak(byte[] key, int offset) throws InvalidKeyException {
191adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project        if (key == null) {
19280a7fbab52b96c9fd47c72f8987d1babe2cd001dElliott Hughes            throw new InvalidKeyException("key == null");
193adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project        }
194adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project        if (key.length - offset < DES_KEY_LEN) {
19580a7fbab52b96c9fd47c72f8987d1babe2cd001dElliott Hughes            throw new InvalidKeyException("key too short");
196adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project        }
197adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project        I:
198adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project        for (int i=0; i<SEMIWEAKS.length; i++) {
199adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project            for (int j=0; j<DES_KEY_LEN; j++) {
200adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                if (SEMIWEAKS[i][j] != key[offset+j]) {
201adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                    continue I;
202adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project                }
203adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project            }
204adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project            return true;
205adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project        }
206adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project        return false;
207adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project    }
208adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project}
209