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