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.OutputLengthException; 7 import org.bouncycastle.crypto.params.KeyParameter; 8 9 /** 10 * a class that provides a basic SKIPJACK engine. 11 */ 12 public class SkipjackEngine 13 implements BlockCipher 14 { 15 static final int BLOCK_SIZE = 8; 16 17 static short ftable[] = 18 { 19 0xa3, 0xd7, 0x09, 0x83, 0xf8, 0x48, 0xf6, 0xf4, 0xb3, 0x21, 0x15, 0x78, 0x99, 0xb1, 0xaf, 0xf9, 20 0xe7, 0x2d, 0x4d, 0x8a, 0xce, 0x4c, 0xca, 0x2e, 0x52, 0x95, 0xd9, 0x1e, 0x4e, 0x38, 0x44, 0x28, 21 0x0a, 0xdf, 0x02, 0xa0, 0x17, 0xf1, 0x60, 0x68, 0x12, 0xb7, 0x7a, 0xc3, 0xe9, 0xfa, 0x3d, 0x53, 22 0x96, 0x84, 0x6b, 0xba, 0xf2, 0x63, 0x9a, 0x19, 0x7c, 0xae, 0xe5, 0xf5, 0xf7, 0x16, 0x6a, 0xa2, 23 0x39, 0xb6, 0x7b, 0x0f, 0xc1, 0x93, 0x81, 0x1b, 0xee, 0xb4, 0x1a, 0xea, 0xd0, 0x91, 0x2f, 0xb8, 24 0x55, 0xb9, 0xda, 0x85, 0x3f, 0x41, 0xbf, 0xe0, 0x5a, 0x58, 0x80, 0x5f, 0x66, 0x0b, 0xd8, 0x90, 25 0x35, 0xd5, 0xc0, 0xa7, 0x33, 0x06, 0x65, 0x69, 0x45, 0x00, 0x94, 0x56, 0x6d, 0x98, 0x9b, 0x76, 26 0x97, 0xfc, 0xb2, 0xc2, 0xb0, 0xfe, 0xdb, 0x20, 0xe1, 0xeb, 0xd6, 0xe4, 0xdd, 0x47, 0x4a, 0x1d, 27 0x42, 0xed, 0x9e, 0x6e, 0x49, 0x3c, 0xcd, 0x43, 0x27, 0xd2, 0x07, 0xd4, 0xde, 0xc7, 0x67, 0x18, 28 0x89, 0xcb, 0x30, 0x1f, 0x8d, 0xc6, 0x8f, 0xaa, 0xc8, 0x74, 0xdc, 0xc9, 0x5d, 0x5c, 0x31, 0xa4, 29 0x70, 0x88, 0x61, 0x2c, 0x9f, 0x0d, 0x2b, 0x87, 0x50, 0x82, 0x54, 0x64, 0x26, 0x7d, 0x03, 0x40, 30 0x34, 0x4b, 0x1c, 0x73, 0xd1, 0xc4, 0xfd, 0x3b, 0xcc, 0xfb, 0x7f, 0xab, 0xe6, 0x3e, 0x5b, 0xa5, 31 0xad, 0x04, 0x23, 0x9c, 0x14, 0x51, 0x22, 0xf0, 0x29, 0x79, 0x71, 0x7e, 0xff, 0x8c, 0x0e, 0xe2, 32 0x0c, 0xef, 0xbc, 0x72, 0x75, 0x6f, 0x37, 0xa1, 0xec, 0xd3, 0x8e, 0x62, 0x8b, 0x86, 0x10, 0xe8, 33 0x08, 0x77, 0x11, 0xbe, 0x92, 0x4f, 0x24, 0xc5, 0x32, 0x36, 0x9d, 0xcf, 0xf3, 0xa6, 0xbb, 0xac, 34 0x5e, 0x6c, 0xa9, 0x13, 0x57, 0x25, 0xb5, 0xe3, 0xbd, 0xa8, 0x3a, 0x01, 0x05, 0x59, 0x2a, 0x46 35 }; 36 37 private int[] key0, key1, key2, key3; 38 private boolean encrypting; 39 40 /** 41 * initialise a SKIPJACK cipher. 42 * 43 * @param encrypting whether or not we are for encryption. 44 * @param params the parameters required to set up the cipher. 45 * @exception IllegalArgumentException if the params argument is 46 * inappropriate. 47 */ init( boolean encrypting, CipherParameters params)48 public void init( 49 boolean encrypting, 50 CipherParameters params) 51 { 52 if (!(params instanceof KeyParameter)) 53 { 54 throw new IllegalArgumentException("invalid parameter passed to SKIPJACK init - " + params.getClass().getName()); 55 } 56 57 byte[] keyBytes = ((KeyParameter)params).getKey(); 58 59 this.encrypting = encrypting; 60 this.key0 = new int[32]; 61 this.key1 = new int[32]; 62 this.key2 = new int[32]; 63 this.key3 = new int[32]; 64 65 // 66 // expand the key to 128 bytes in 4 parts (saving us a modulo, multiply 67 // and an addition). 68 // 69 for (int i = 0; i < 32; i ++) 70 { 71 key0[i] = keyBytes[(i * 4) % 10] & 0xff; 72 key1[i] = keyBytes[(i * 4 + 1) % 10] & 0xff; 73 key2[i] = keyBytes[(i * 4 + 2) % 10] & 0xff; 74 key3[i] = keyBytes[(i * 4 + 3) % 10] & 0xff; 75 } 76 } 77 getAlgorithmName()78 public String getAlgorithmName() 79 { 80 return "SKIPJACK"; 81 } 82 getBlockSize()83 public int getBlockSize() 84 { 85 return BLOCK_SIZE; 86 } 87 processBlock( byte[] in, int inOff, byte[] out, int outOff)88 public int processBlock( 89 byte[] in, 90 int inOff, 91 byte[] out, 92 int outOff) 93 { 94 if (key1 == null) 95 { 96 throw new IllegalStateException("SKIPJACK engine not initialised"); 97 } 98 99 if ((inOff + BLOCK_SIZE) > in.length) 100 { 101 throw new DataLengthException("input buffer too short"); 102 } 103 104 if ((outOff + BLOCK_SIZE) > out.length) 105 { 106 throw new OutputLengthException("output buffer too short"); 107 } 108 109 if (encrypting) 110 { 111 encryptBlock(in, inOff, out, outOff); 112 } 113 else 114 { 115 decryptBlock(in, inOff, out, outOff); 116 } 117 118 return BLOCK_SIZE; 119 } 120 reset()121 public void reset() 122 { 123 } 124 125 /** 126 * The G permutation 127 */ g( int k, int w)128 private int g( 129 int k, 130 int w) 131 { 132 int g1, g2, g3, g4, g5, g6; 133 134 g1 = (w >> 8) & 0xff; 135 g2 = w & 0xff; 136 137 g3 = ftable[g2 ^ key0[k]] ^ g1; 138 g4 = ftable[g3 ^ key1[k]] ^ g2; 139 g5 = ftable[g4 ^ key2[k]] ^ g3; 140 g6 = ftable[g5 ^ key3[k]] ^ g4; 141 142 return ((g5 << 8) + g6); 143 } 144 encryptBlock( byte[] in, int inOff, byte[] out, int outOff)145 public int encryptBlock( 146 byte[] in, 147 int inOff, 148 byte[] out, 149 int outOff) 150 { 151 int w1 = (in[inOff + 0] << 8) + (in[inOff + 1] & 0xff); 152 int w2 = (in[inOff + 2] << 8) + (in[inOff + 3] & 0xff); 153 int w3 = (in[inOff + 4] << 8) + (in[inOff + 5] & 0xff); 154 int w4 = (in[inOff + 6] << 8) + (in[inOff + 7] & 0xff); 155 156 int k = 0; 157 158 for (int t = 0; t < 2; t++) 159 { 160 for(int i = 0; i < 8; i++) 161 { 162 int tmp = w4; 163 w4 = w3; 164 w3 = w2; 165 w2 = g(k, w1); 166 w1 = w2 ^ tmp ^ (k + 1); 167 k++; 168 } 169 170 for(int i = 0; i < 8; i++) 171 { 172 int tmp = w4; 173 w4 = w3; 174 w3 = w1 ^ w2 ^ (k + 1); 175 w2 = g(k, w1); 176 w1 = tmp; 177 k++; 178 } 179 } 180 181 out[outOff + 0] = (byte)((w1 >> 8)); 182 out[outOff + 1] = (byte)(w1); 183 out[outOff + 2] = (byte)((w2 >> 8)); 184 out[outOff + 3] = (byte)(w2); 185 out[outOff + 4] = (byte)((w3 >> 8)); 186 out[outOff + 5] = (byte)(w3); 187 out[outOff + 6] = (byte)((w4 >> 8)); 188 out[outOff + 7] = (byte)(w4); 189 190 return BLOCK_SIZE; 191 } 192 193 /** 194 * the inverse of the G permutation. 195 */ h( int k, int w)196 private int h( 197 int k, 198 int w) 199 { 200 int h1, h2, h3, h4, h5, h6; 201 202 h1 = w & 0xff; 203 h2 = (w >> 8) & 0xff; 204 205 h3 = ftable[h2 ^ key3[k]] ^ h1; 206 h4 = ftable[h3 ^ key2[k]] ^ h2; 207 h5 = ftable[h4 ^ key1[k]] ^ h3; 208 h6 = ftable[h5 ^ key0[k]] ^ h4; 209 210 return ((h6 << 8) + h5); 211 } 212 decryptBlock( byte[] in, int inOff, byte[] out, int outOff)213 public int decryptBlock( 214 byte[] in, 215 int inOff, 216 byte[] out, 217 int outOff) 218 { 219 int w2 = (in[inOff + 0] << 8) + (in[inOff + 1] & 0xff); 220 int w1 = (in[inOff + 2] << 8) + (in[inOff + 3] & 0xff); 221 int w4 = (in[inOff + 4] << 8) + (in[inOff + 5] & 0xff); 222 int w3 = (in[inOff + 6] << 8) + (in[inOff + 7] & 0xff); 223 224 int k = 31; 225 226 for (int t = 0; t < 2; t++) 227 { 228 for(int i = 0; i < 8; i++) 229 { 230 int tmp = w4; 231 w4 = w3; 232 w3 = w2; 233 w2 = h(k, w1); 234 w1 = w2 ^ tmp ^ (k + 1); 235 k--; 236 } 237 238 for(int i = 0; i < 8; i++) 239 { 240 int tmp = w4; 241 w4 = w3; 242 w3 = w1 ^ w2 ^ (k + 1); 243 w2 = h(k, w1); 244 w1 = tmp; 245 k--; 246 } 247 } 248 249 out[outOff + 0] = (byte)((w2 >> 8)); 250 out[outOff + 1] = (byte)(w2); 251 out[outOff + 2] = (byte)((w1 >> 8)); 252 out[outOff + 3] = (byte)(w1); 253 out[outOff + 4] = (byte)((w4 >> 8)); 254 out[outOff + 5] = (byte)(w4); 255 out[outOff + 6] = (byte)((w3 >> 8)); 256 out[outOff + 7] = (byte)(w3); 257 258 return BLOCK_SIZE; 259 } 260 } 261