1package org.bouncycastle.crypto.engines;
2
3import org.bouncycastle.crypto.BlockCipher;
4import org.bouncycastle.crypto.CipherParameters;
5import org.bouncycastle.crypto.DataLengthException;
6import org.bouncycastle.crypto.OutputLengthException;
7import org.bouncycastle.crypto.params.KeyParameter;
8import org.bouncycastle.crypto.params.RC2Parameters;
9
10/**
11 * an implementation of RC2 as described in RFC 2268
12 *      "A Description of the RC2(r) Encryption Algorithm" R. Rivest.
13 */
14public class RC2Engine
15    implements BlockCipher
16{
17    //
18    // the values we use for key expansion (based on the digits of PI)
19    //
20    private static byte[] piTable =
21    {
22        (byte)0xd9, (byte)0x78, (byte)0xf9, (byte)0xc4, (byte)0x19, (byte)0xdd, (byte)0xb5, (byte)0xed,
23        (byte)0x28, (byte)0xe9, (byte)0xfd, (byte)0x79, (byte)0x4a, (byte)0xa0, (byte)0xd8, (byte)0x9d,
24        (byte)0xc6, (byte)0x7e, (byte)0x37, (byte)0x83, (byte)0x2b, (byte)0x76, (byte)0x53, (byte)0x8e,
25        (byte)0x62, (byte)0x4c, (byte)0x64, (byte)0x88, (byte)0x44, (byte)0x8b, (byte)0xfb, (byte)0xa2,
26        (byte)0x17, (byte)0x9a, (byte)0x59, (byte)0xf5, (byte)0x87, (byte)0xb3, (byte)0x4f, (byte)0x13,
27        (byte)0x61, (byte)0x45, (byte)0x6d, (byte)0x8d, (byte)0x9, (byte)0x81, (byte)0x7d, (byte)0x32,
28        (byte)0xbd, (byte)0x8f, (byte)0x40, (byte)0xeb, (byte)0x86, (byte)0xb7, (byte)0x7b, (byte)0xb,
29        (byte)0xf0, (byte)0x95, (byte)0x21, (byte)0x22, (byte)0x5c, (byte)0x6b, (byte)0x4e, (byte)0x82,
30        (byte)0x54, (byte)0xd6, (byte)0x65, (byte)0x93, (byte)0xce, (byte)0x60, (byte)0xb2, (byte)0x1c,
31        (byte)0x73, (byte)0x56, (byte)0xc0, (byte)0x14, (byte)0xa7, (byte)0x8c, (byte)0xf1, (byte)0xdc,
32        (byte)0x12, (byte)0x75, (byte)0xca, (byte)0x1f, (byte)0x3b, (byte)0xbe, (byte)0xe4, (byte)0xd1,
33        (byte)0x42, (byte)0x3d, (byte)0xd4, (byte)0x30, (byte)0xa3, (byte)0x3c, (byte)0xb6, (byte)0x26,
34        (byte)0x6f, (byte)0xbf, (byte)0xe, (byte)0xda, (byte)0x46, (byte)0x69, (byte)0x7, (byte)0x57,
35        (byte)0x27, (byte)0xf2, (byte)0x1d, (byte)0x9b, (byte)0xbc, (byte)0x94, (byte)0x43, (byte)0x3,
36        (byte)0xf8, (byte)0x11, (byte)0xc7, (byte)0xf6, (byte)0x90, (byte)0xef, (byte)0x3e, (byte)0xe7,
37        (byte)0x6, (byte)0xc3, (byte)0xd5, (byte)0x2f, (byte)0xc8, (byte)0x66, (byte)0x1e, (byte)0xd7,
38        (byte)0x8, (byte)0xe8, (byte)0xea, (byte)0xde, (byte)0x80, (byte)0x52, (byte)0xee, (byte)0xf7,
39        (byte)0x84, (byte)0xaa, (byte)0x72, (byte)0xac, (byte)0x35, (byte)0x4d, (byte)0x6a, (byte)0x2a,
40        (byte)0x96, (byte)0x1a, (byte)0xd2, (byte)0x71, (byte)0x5a, (byte)0x15, (byte)0x49, (byte)0x74,
41        (byte)0x4b, (byte)0x9f, (byte)0xd0, (byte)0x5e, (byte)0x4, (byte)0x18, (byte)0xa4, (byte)0xec,
42        (byte)0xc2, (byte)0xe0, (byte)0x41, (byte)0x6e, (byte)0xf, (byte)0x51, (byte)0xcb, (byte)0xcc,
43        (byte)0x24, (byte)0x91, (byte)0xaf, (byte)0x50, (byte)0xa1, (byte)0xf4, (byte)0x70, (byte)0x39,
44        (byte)0x99, (byte)0x7c, (byte)0x3a, (byte)0x85, (byte)0x23, (byte)0xb8, (byte)0xb4, (byte)0x7a,
45        (byte)0xfc, (byte)0x2, (byte)0x36, (byte)0x5b, (byte)0x25, (byte)0x55, (byte)0x97, (byte)0x31,
46        (byte)0x2d, (byte)0x5d, (byte)0xfa, (byte)0x98, (byte)0xe3, (byte)0x8a, (byte)0x92, (byte)0xae,
47        (byte)0x5, (byte)0xdf, (byte)0x29, (byte)0x10, (byte)0x67, (byte)0x6c, (byte)0xba, (byte)0xc9,
48        (byte)0xd3, (byte)0x0, (byte)0xe6, (byte)0xcf, (byte)0xe1, (byte)0x9e, (byte)0xa8, (byte)0x2c,
49        (byte)0x63, (byte)0x16, (byte)0x1, (byte)0x3f, (byte)0x58, (byte)0xe2, (byte)0x89, (byte)0xa9,
50        (byte)0xd, (byte)0x38, (byte)0x34, (byte)0x1b, (byte)0xab, (byte)0x33, (byte)0xff, (byte)0xb0,
51        (byte)0xbb, (byte)0x48, (byte)0xc, (byte)0x5f, (byte)0xb9, (byte)0xb1, (byte)0xcd, (byte)0x2e,
52        (byte)0xc5, (byte)0xf3, (byte)0xdb, (byte)0x47, (byte)0xe5, (byte)0xa5, (byte)0x9c, (byte)0x77,
53        (byte)0xa, (byte)0xa6, (byte)0x20, (byte)0x68, (byte)0xfe, (byte)0x7f, (byte)0xc1, (byte)0xad
54    };
55
56    private static final int BLOCK_SIZE = 8;
57
58    private int[]   workingKey;
59    private boolean encrypting;
60
61    private int[] generateWorkingKey(
62        byte[]      key,
63        int         bits)
64    {
65        int     x;
66        int[]   xKey = new int[128];
67
68        for (int i = 0; i != key.length; i++)
69        {
70            xKey[i] = key[i] & 0xff;
71        }
72
73        // Phase 1: Expand input key to 128 bytes
74        int len = key.length;
75
76        if (len < 128)
77        {
78            int     index = 0;
79
80            x = xKey[len - 1];
81
82            do
83            {
84                x = piTable[(x + xKey[index++]) & 255] & 0xff;
85                xKey[len++] = x;
86            }
87            while (len < 128);
88        }
89
90        // Phase 2 - reduce effective key size to "bits"
91        len = (bits + 7) >> 3;
92        x = piTable[xKey[128 - len] & (255 >> (7 & -bits))] & 0xff;
93        xKey[128 - len] = x;
94
95        for (int i = 128 - len - 1; i >= 0; i--)
96        {
97                x = piTable[x ^ xKey[i + len]] & 0xff;
98                xKey[i] = x;
99        }
100
101        // Phase 3 - copy to newKey in little-endian order
102        int[] newKey = new int[64];
103
104        for (int i = 0; i != newKey.length; i++)
105        {
106            newKey[i] = (xKey[2 * i] + (xKey[2 * i + 1] << 8));
107        }
108
109        return newKey;
110    }
111
112    /**
113     * initialise a RC2 cipher.
114     *
115     * @param encrypting whether or not we are for encryption.
116     * @param params the parameters required to set up the cipher.
117     * @exception IllegalArgumentException if the params argument is
118     * inappropriate.
119     */
120    public void init(
121        boolean           encrypting,
122        CipherParameters  params)
123    {
124        this.encrypting = encrypting;
125
126        if (params instanceof RC2Parameters)
127        {
128            RC2Parameters   param = (RC2Parameters)params;
129
130            workingKey = generateWorkingKey(param.getKey(),
131                                            param.getEffectiveKeyBits());
132        }
133        else if (params instanceof KeyParameter)
134        {
135            byte[]    key = ((KeyParameter)params).getKey();
136
137            workingKey = generateWorkingKey(key, key.length * 8);
138        }
139        else
140        {
141            throw new IllegalArgumentException("invalid parameter passed to RC2 init - " + params.getClass().getName());
142        }
143
144    }
145
146    public void reset()
147    {
148    }
149
150    public String getAlgorithmName()
151    {
152        return "RC2";
153    }
154
155    public int getBlockSize()
156    {
157        return BLOCK_SIZE;
158    }
159
160    public final int processBlock(
161        byte[] in,
162        int inOff,
163        byte[] out,
164        int outOff)
165    {
166        if (workingKey == null)
167        {
168            throw new IllegalStateException("RC2 engine not initialised");
169        }
170
171        if ((inOff + BLOCK_SIZE) > in.length)
172        {
173            throw new DataLengthException("input buffer too short");
174        }
175
176        if ((outOff + BLOCK_SIZE) > out.length)
177        {
178            throw new OutputLengthException("output buffer too short");
179        }
180
181        if (encrypting)
182        {
183            encryptBlock(in, inOff, out, outOff);
184        }
185        else
186        {
187            decryptBlock(in, inOff, out, outOff);
188        }
189
190        return BLOCK_SIZE;
191    }
192
193    /**
194     * return the result rotating the 16 bit number in x left by y
195     */
196    private int rotateWordLeft(
197        int x,
198        int y)
199    {
200        x &= 0xffff;
201        return (x << y) | (x >> (16 - y));
202    }
203
204    private void encryptBlock(
205        byte[]  in,
206        int     inOff,
207        byte[]  out,
208        int     outOff)
209    {
210        int x76, x54, x32, x10;
211
212        x76 = ((in[inOff + 7] & 0xff) << 8) + (in[inOff + 6] & 0xff);
213        x54 = ((in[inOff + 5] & 0xff) << 8) + (in[inOff + 4] & 0xff);
214        x32 = ((in[inOff + 3] & 0xff) << 8) + (in[inOff + 2] & 0xff);
215        x10 = ((in[inOff + 1] & 0xff) << 8) + (in[inOff + 0] & 0xff);
216
217        for (int i = 0; i <= 16; i += 4)
218        {
219                x10 = rotateWordLeft(x10 + (x32 & ~x76) + (x54 & x76) + workingKey[i  ], 1);
220                x32 = rotateWordLeft(x32 + (x54 & ~x10) + (x76 & x10) + workingKey[i+1], 2);
221                x54 = rotateWordLeft(x54 + (x76 & ~x32) + (x10 & x32) + workingKey[i+2], 3);
222                x76 = rotateWordLeft(x76 + (x10 & ~x54) + (x32 & x54) + workingKey[i+3], 5);
223        }
224
225        x10 += workingKey[x76 & 63];
226        x32 += workingKey[x10 & 63];
227        x54 += workingKey[x32 & 63];
228        x76 += workingKey[x54 & 63];
229
230        for (int i = 20; i <= 40; i += 4)
231        {
232                x10 = rotateWordLeft(x10 + (x32 & ~x76) + (x54 & x76) + workingKey[i  ], 1);
233                x32 = rotateWordLeft(x32 + (x54 & ~x10) + (x76 & x10) + workingKey[i+1], 2);
234                x54 = rotateWordLeft(x54 + (x76 & ~x32) + (x10 & x32) + workingKey[i+2], 3);
235                x76 = rotateWordLeft(x76 + (x10 & ~x54) + (x32 & x54) + workingKey[i+3], 5);
236        }
237
238        x10 += workingKey[x76 & 63];
239        x32 += workingKey[x10 & 63];
240        x54 += workingKey[x32 & 63];
241        x76 += workingKey[x54 & 63];
242
243        for (int i = 44; i < 64; i += 4)
244        {
245                x10 = rotateWordLeft(x10 + (x32 & ~x76) + (x54 & x76) + workingKey[i  ], 1);
246                x32 = rotateWordLeft(x32 + (x54 & ~x10) + (x76 & x10) + workingKey[i+1], 2);
247                x54 = rotateWordLeft(x54 + (x76 & ~x32) + (x10 & x32) + workingKey[i+2], 3);
248                x76 = rotateWordLeft(x76 + (x10 & ~x54) + (x32 & x54) + workingKey[i+3], 5);
249        }
250
251        out[outOff + 0] = (byte)x10;
252        out[outOff + 1] = (byte)(x10 >> 8);
253        out[outOff + 2] = (byte)x32;
254        out[outOff + 3] = (byte)(x32 >> 8);
255        out[outOff + 4] = (byte)x54;
256        out[outOff + 5] = (byte)(x54 >> 8);
257        out[outOff + 6] = (byte)x76;
258        out[outOff + 7] = (byte)(x76 >> 8);
259    }
260
261    private void decryptBlock(
262        byte[]  in,
263        int     inOff,
264        byte[]  out,
265        int     outOff)
266    {
267        int x76, x54, x32, x10;
268
269        x76 = ((in[inOff + 7] & 0xff) << 8) + (in[inOff + 6] & 0xff);
270        x54 = ((in[inOff + 5] & 0xff) << 8) + (in[inOff + 4] & 0xff);
271        x32 = ((in[inOff + 3] & 0xff) << 8) + (in[inOff + 2] & 0xff);
272        x10 = ((in[inOff + 1] & 0xff) << 8) + (in[inOff + 0] & 0xff);
273
274        for (int i = 60; i >= 44; i -= 4)
275        {
276            x76 = rotateWordLeft(x76, 11) - ((x10 & ~x54) + (x32 & x54) + workingKey[i+3]);
277            x54 = rotateWordLeft(x54, 13) - ((x76 & ~x32) + (x10 & x32) + workingKey[i+2]);
278            x32 = rotateWordLeft(x32, 14) - ((x54 & ~x10) + (x76 & x10) + workingKey[i+1]);
279            x10 = rotateWordLeft(x10, 15) - ((x32 & ~x76) + (x54 & x76) + workingKey[i  ]);
280        }
281
282        x76 -= workingKey[x54 & 63];
283        x54 -= workingKey[x32 & 63];
284        x32 -= workingKey[x10 & 63];
285        x10 -= workingKey[x76 & 63];
286
287        for (int i = 40; i >= 20; i -= 4)
288        {
289            x76 = rotateWordLeft(x76, 11) - ((x10 & ~x54) + (x32 & x54) + workingKey[i+3]);
290            x54 = rotateWordLeft(x54, 13) - ((x76 & ~x32) + (x10 & x32) + workingKey[i+2]);
291            x32 = rotateWordLeft(x32, 14) - ((x54 & ~x10) + (x76 & x10) + workingKey[i+1]);
292            x10 = rotateWordLeft(x10, 15) - ((x32 & ~x76) + (x54 & x76) + workingKey[i  ]);
293        }
294
295        x76 -= workingKey[x54 & 63];
296        x54 -= workingKey[x32 & 63];
297        x32 -= workingKey[x10 & 63];
298        x10 -= workingKey[x76 & 63];
299
300        for (int i = 16; i >= 0; i -= 4)
301        {
302            x76 = rotateWordLeft(x76, 11) - ((x10 & ~x54) + (x32 & x54) + workingKey[i+3]);
303            x54 = rotateWordLeft(x54, 13) - ((x76 & ~x32) + (x10 & x32) + workingKey[i+2]);
304            x32 = rotateWordLeft(x32, 14) - ((x54 & ~x10) + (x76 & x10) + workingKey[i+1]);
305            x10 = rotateWordLeft(x10, 15) - ((x32 & ~x76) + (x54 & x76) + workingKey[i  ]);
306        }
307
308        out[outOff + 0] = (byte)x10;
309        out[outOff + 1] = (byte)(x10 >> 8);
310        out[outOff + 2] = (byte)x32;
311        out[outOff + 3] = (byte)(x32 >> 8);
312        out[outOff + 4] = (byte)x54;
313        out[outOff + 5] = (byte)(x54 >> 8);
314        out[outOff + 6] = (byte)x76;
315        out[outOff + 7] = (byte)(x76 >> 8);
316    }
317}
318