1/*
2 *  Licensed to the Apache Software Foundation (ASF) under one or more
3 *  contributor license agreements.  See the NOTICE file distributed with
4 *  this work for additional information regarding copyright ownership.
5 *  The ASF licenses this file to You under the Apache License, Version 2.0
6 *  (the "License"); you may not use this file except in compliance with
7 *  the License.  You may obtain a copy of the License at
8 *
9 *     http://www.apache.org/licenses/LICENSE-2.0
10 *
11 *  Unless required by applicable law or agreed to in writing, software
12 *  distributed under the License is distributed on an "AS IS" BASIS,
13 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 *  See the License for the specific language governing permissions and
15 *  limitations under the License.
16 */
17
18package javax.crypto.spec;
19
20import java.security.InvalidKeyException;
21import java.security.spec.KeySpec;
22
23import org.apache.harmony.crypto.internal.nls.Messages;
24
25/**
26 * The key specification for a DES key.
27 */
28public class DESKeySpec implements KeySpec {
29
30    /**
31     * The length of a DES key in bytes.
32     */
33    public static final int DES_KEY_LEN = 8;
34
35    private final byte[] key;
36
37    // DES weak and semi-weak keys
38    // Got from:
39    // FIP PUB 74
40    // FEDERAL INFORMATION PROCESSING STANDARDS PUBLICATION 1981
41    // GUIDELINES FOR IMPLEMENTING AND USING THE NBS DATA ENCRYPTION STANDARD
42    // http://www.dice.ucl.ac.be/crypto/standards/fips/fip74/fip74-1.pdf
43    private static final byte[][] SEMIWEAKS = {
44                {(byte) 0xE0, (byte) 0x01, (byte) 0xE0, (byte) 0x01,
45                 (byte) 0xF1, (byte) 0x01, (byte) 0xF1, (byte) 0x01},
46
47                {(byte) 0x01, (byte) 0xE0, (byte) 0x01, (byte) 0xE0,
48                 (byte) 0x01, (byte) 0xF1, (byte) 0x01, (byte) 0xF1},
49
50                {(byte) 0xFE, (byte) 0x1F, (byte) 0xFE, (byte) 0x1F,
51                 (byte) 0xFE, (byte) 0x0E, (byte) 0xFE, (byte) 0x0E},
52
53                {(byte) 0x1F, (byte) 0xFE, (byte) 0x1F, (byte) 0xFE,
54                 (byte) 0x0E, (byte) 0xFE, (byte) 0x0E, (byte) 0xFE},
55
56                {(byte) 0xE0, (byte) 0x1F, (byte) 0xE0, (byte) 0x1F,
57                 (byte) 0xF1, (byte) 0x0E, (byte) 0xF1, (byte) 0x0E},
58
59                {(byte) 0x1F, (byte) 0xE0, (byte) 0x1F, (byte) 0xE0,
60                 (byte) 0x0E, (byte) 0xF1, (byte) 0x0E, (byte) 0xF1},
61
62                {(byte) 0x01, (byte) 0xFE, (byte) 0x01, (byte) 0xFE,
63                 (byte) 0x01, (byte) 0xFE, (byte) 0x01, (byte) 0xFE},
64
65                {(byte) 0xFE, (byte) 0x01, (byte) 0xFE, (byte) 0x01,
66                 (byte) 0xFE, (byte) 0x01, (byte) 0xFE, (byte) 0x01},
67
68                {(byte) 0x01, (byte) 0x1F, (byte) 0x01, (byte) 0x1F,
69                 (byte) 0x01, (byte) 0x0E, (byte) 0x01, (byte) 0x0E},
70
71                {(byte) 0x1F, (byte) 0x01, (byte) 0x1F, (byte) 0x01,
72                 (byte) 0x0E, (byte) 0x01, (byte) 0x0E, (byte) 0x01},
73
74                {(byte) 0xE0, (byte) 0xFE, (byte) 0xE0, (byte) 0xFE,
75                 (byte) 0xF1, (byte) 0xFE, (byte) 0xF1, (byte) 0xFE},
76
77                {(byte) 0xFE, (byte) 0xE0, (byte) 0xFE, (byte) 0xE0,
78                 (byte) 0xFE, (byte) 0xF1, (byte) 0xFE, (byte) 0xF1},
79
80                {(byte) 0x01, (byte) 0x01, (byte) 0x01, (byte) 0x01,
81                 (byte) 0x01, (byte) 0x01, (byte) 0x01, (byte) 0x01},
82
83                {(byte) 0xFE, (byte) 0xFE, (byte) 0xFE, (byte) 0xFE,
84                 (byte) 0xFE, (byte) 0xFE, (byte) 0xFE, (byte) 0xFE},
85
86                {(byte) 0xE0, (byte) 0xE0, (byte) 0xE0, (byte) 0xE0,
87                 (byte) 0xF1, (byte) 0xF1, (byte) 0xF1, (byte) 0xF1},
88
89                {(byte) 0x1F, (byte) 0x1F, (byte) 0x1F, (byte) 0x1F,
90                 (byte) 0x0E, (byte) 0x0E, (byte) 0x0E, (byte) 0x0E},
91
92                };
93
94    /**
95     * Creates a new <code>DESKeySpec</code> from the first 8 bytes of the
96     * specified key data.
97     *
98     * @param key
99     *            the key data.
100     * @throws InvalidKeyException
101     *             if the length of the specified key data is less than 8.
102     */
103    public DESKeySpec(byte[] key) throws InvalidKeyException {
104        this(key, 0);
105    }
106
107    /**
108     * Creates a new <code>DESKeySpec</code> from the first 8 bytes of the
109     * specified key data starting at <code>offset</code>.
110     *
111     * @param key
112     *            the key data
113     * @param offset
114     *            the offset to start at.
115     * @throws InvalidKeyException
116     *             if the length of the specified key data starting at offset is
117     *             less than 8.
118     */
119    public DESKeySpec(byte[] key, int offset)
120                throws InvalidKeyException {
121        if (key == null) {
122            throw new NullPointerException(Messages.getString("crypto.2F")); //$NON-NLS-1$
123        }
124        if (key.length - offset < DES_KEY_LEN) {
125            throw new InvalidKeyException(
126                    Messages.getString("crypto.40")); //$NON-NLS-1$
127        }
128        this.key = new byte[DES_KEY_LEN];
129        System.arraycopy(key, offset, this.key, 0, DES_KEY_LEN);
130    }
131
132    /**
133     * Returns a copy of the key.
134     *
135     * @return a copy of the key.
136     */
137    public byte[] getKey() {
138        byte[] result = new byte[DES_KEY_LEN];
139        System.arraycopy(this.key, 0, result, 0, DES_KEY_LEN);
140        return result;
141    }
142
143    /**
144     * Returns whether the specified key data starting at <code>offset</code> is
145     * <i>parity-adjusted</i>.
146     *
147     * @param key
148     *            the key data.
149     * @param offset
150     *            the offset to start checking at.
151     * @return {@code true} if the specified key data is parity-adjusted,
152     *            {@code false} otherwise.
153     * @throws InvalidKeyException
154     *             if the length of the key data starting at offset is less than
155     *             8, or the key is null.
156     */
157    public static boolean isParityAdjusted(byte[] key, int offset)
158            throws InvalidKeyException {
159        if (key == null) {
160            throw new InvalidKeyException(Messages.getString("crypto.2F")); //$NON-NLS-1$
161        }
162        if (key.length - offset < DES_KEY_LEN) {
163            throw new InvalidKeyException(
164                    Messages.getString("crypto.40")); //$NON-NLS-1$
165        }
166
167        int byteKey = 0;
168
169        for (int i = offset; i < DES_KEY_LEN; i++) {
170            byteKey = key[i];
171
172            byteKey ^= byteKey >> 1;
173            byteKey ^= byteKey >> 2;
174            byteKey ^= byteKey >> 4;
175
176            if ((byteKey & 1) == 0) {
177                return false;
178            }
179        }
180        return true;
181    }
182
183    /**
184     * Returns whether the specified key data starting at <code>offset</code> is
185     * weak or semi-weak.
186     *
187     * @param key
188     *            the key data.
189     * @param offset
190     *            the offset to start checking at.
191     * @return {@code true} if the specified key data is weak or semi-weak.
192     * @throws InvalidKeyException
193     *             if the length of the key data starting at offset is less than
194     *             8, or it is null.
195     */
196    public static boolean isWeak(byte[] key, int offset)
197              throws InvalidKeyException {
198        if (key == null) {
199            throw new InvalidKeyException(Messages.getString("crypto.2F")); //$NON-NLS-1$
200        }
201        if (key.length - offset < DES_KEY_LEN) {
202            throw new InvalidKeyException(
203                    Messages.getString("crypto.40")); //$NON-NLS-1$
204        }
205        I:
206        for (int i=0; i<SEMIWEAKS.length; i++) {
207            for (int j=0; j<DES_KEY_LEN; j++) {
208                if (SEMIWEAKS[i][j] != key[offset+j]) {
209                    continue I;
210                }
211            }
212            return true;
213        }
214        return false;
215    }
216}
217
218