1 /* $OpenBSD: cast.c,v 1.3 2005/03/24 11:45:28 hshoexer Exp $ */ 2 3 /* 4 * CAST-128 in C 5 * Written by Steve Reid <sreid@sea-to-sky.net> 6 * 100% Public Domain - no warranty 7 * Released 1997.10.11 8 */ 9 10 #include <sys/types.h> 11 #include <crypto/cast.h> 12 #include <crypto/castsb.h> 13 14 /* Macros to access 8-bit bytes out of a 32-bit word */ 15 #define U_INT8_Ta(x) ( (u_int8_t) (x>>24) ) 16 #define U_INT8_Tb(x) ( (u_int8_t) ((x>>16)&255) ) 17 #define U_INT8_Tc(x) ( (u_int8_t) ((x>>8)&255) ) 18 #define U_INT8_Td(x) ( (u_int8_t) ((x)&255) ) 19 20 /* Circular left shift */ 21 #define ROL(x, n) ( ((x)<<(n)) | ((x)>>(32-(n))) ) 22 23 /* CAST-128 uses three different round functions */ 24 #define F1(l, r, i) \ 25 t = ROL(key->xkey[i] + r, key->xkey[i+16]); \ 26 l ^= ((cast_sbox1[U_INT8_Ta(t)] ^ cast_sbox2[U_INT8_Tb(t)]) - \ 27 cast_sbox3[U_INT8_Tc(t)]) + cast_sbox4[U_INT8_Td(t)]; 28 #define F2(l, r, i) \ 29 t = ROL(key->xkey[i] ^ r, key->xkey[i+16]); \ 30 l ^= ((cast_sbox1[U_INT8_Ta(t)] - cast_sbox2[U_INT8_Tb(t)]) + \ 31 cast_sbox3[U_INT8_Tc(t)]) ^ cast_sbox4[U_INT8_Td(t)]; 32 #define F3(l, r, i) \ 33 t = ROL(key->xkey[i] - r, key->xkey[i+16]); \ 34 l ^= ((cast_sbox1[U_INT8_Ta(t)] + cast_sbox2[U_INT8_Tb(t)]) ^ \ 35 cast_sbox3[U_INT8_Tc(t)]) - cast_sbox4[U_INT8_Td(t)]; 36 37 38 /***** Encryption Function *****/ 39 40 void 41 cast_encrypt(cast_key *key, u_int8_t *inblock, u_int8_t *outblock) 42 { 43 u_int32_t t, l, r; 44 45 /* Get inblock into l,r */ 46 l = ((u_int32_t)inblock[0] << 24) | ((u_int32_t)inblock[1] << 16) | 47 ((u_int32_t)inblock[2] << 8) | (u_int32_t)inblock[3]; 48 r = ((u_int32_t)inblock[4] << 24) | ((u_int32_t)inblock[5] << 16) | 49 ((u_int32_t)inblock[6] << 8) | (u_int32_t)inblock[7]; 50 /* Do the work */ 51 F1(l, r, 0); 52 F2(r, l, 1); 53 F3(l, r, 2); 54 F1(r, l, 3); 55 F2(l, r, 4); 56 F3(r, l, 5); 57 F1(l, r, 6); 58 F2(r, l, 7); 59 F3(l, r, 8); 60 F1(r, l, 9); 61 F2(l, r, 10); 62 F3(r, l, 11); 63 /* Only do full 16 rounds if key length > 80 bits */ 64 if (key->rounds > 12) { 65 F1(l, r, 12); 66 F2(r, l, 13); 67 F3(l, r, 14); 68 F1(r, l, 15); 69 } 70 /* Put l,r into outblock */ 71 outblock[0] = U_INT8_Ta(r); 72 outblock[1] = U_INT8_Tb(r); 73 outblock[2] = U_INT8_Tc(r); 74 outblock[3] = U_INT8_Td(r); 75 outblock[4] = U_INT8_Ta(l); 76 outblock[5] = U_INT8_Tb(l); 77 outblock[6] = U_INT8_Tc(l); 78 outblock[7] = U_INT8_Td(l); 79 /* Wipe clean */ 80 t = l = r = 0; 81 } 82 83 84 /***** Decryption Function *****/ 85 86 void 87 cast_decrypt(cast_key *key, u_int8_t *inblock, u_int8_t *outblock) 88 { 89 u_int32_t t, l, r; 90 91 /* Get inblock into l,r */ 92 r = ((u_int32_t)inblock[0] << 24) | ((u_int32_t)inblock[1] << 16) | 93 ((u_int32_t)inblock[2] << 8) | (u_int32_t)inblock[3]; 94 l = ((u_int32_t)inblock[4] << 24) | ((u_int32_t)inblock[5] << 16) | 95 ((u_int32_t)inblock[6] << 8) | (u_int32_t)inblock[7]; 96 /* Do the work */ 97 /* Only do full 16 rounds if key length > 80 bits */ 98 if (key->rounds > 12) { 99 F1(r, l, 15); 100 F3(l, r, 14); 101 F2(r, l, 13); 102 F1(l, r, 12); 103 } 104 F3(r, l, 11); 105 F2(l, r, 10); 106 F1(r, l, 9); 107 F3(l, r, 8); 108 F2(r, l, 7); 109 F1(l, r, 6); 110 F3(r, l, 5); 111 F2(l, r, 4); 112 F1(r, l, 3); 113 F3(l, r, 2); 114 F2(r, l, 1); 115 F1(l, r, 0); 116 /* Put l,r into outblock */ 117 outblock[0] = U_INT8_Ta(l); 118 outblock[1] = U_INT8_Tb(l); 119 outblock[2] = U_INT8_Tc(l); 120 outblock[3] = U_INT8_Td(l); 121 outblock[4] = U_INT8_Ta(r); 122 outblock[5] = U_INT8_Tb(r); 123 outblock[6] = U_INT8_Tc(r); 124 outblock[7] = U_INT8_Td(r); 125 /* Wipe clean */ 126 t = l = r = 0; 127 } 128 129 130 /***** Key Schedule *****/ 131 132 void 133 cast_setkey(cast_key *key, u_int8_t *rawkey, int keybytes) 134 { 135 u_int32_t t[4], z[4], x[4]; 136 int i; 137 138 /* Set number of rounds to 12 or 16, depending on key length */ 139 key->rounds = (keybytes <= 10 ? 12 : 16); 140 141 /* Copy key to workspace x */ 142 for (i = 0; i < 4; i++) { 143 x[i] = 0; 144 if ((i*4+0) < keybytes) x[i] = (u_int32_t)rawkey[i*4+0] << 24; 145 if ((i*4+1) < keybytes) x[i] |= (u_int32_t)rawkey[i*4+1] << 16; 146 if ((i*4+2) < keybytes) x[i] |= (u_int32_t)rawkey[i*4+2] << 8; 147 if ((i*4+3) < keybytes) x[i] |= (u_int32_t)rawkey[i*4+3]; 148 } 149 /* Generate 32 subkeys, four at a time */ 150 for (i = 0; i < 32; i+=4) { 151 switch (i & 4) { 152 case 0: 153 t[0] = z[0] = x[0] ^ cast_sbox5[U_INT8_Tb(x[3])] ^ 154 cast_sbox6[U_INT8_Td(x[3])] ^ 155 cast_sbox7[U_INT8_Ta(x[3])] ^ 156 cast_sbox8[U_INT8_Tc(x[3])] ^ 157 cast_sbox7[U_INT8_Ta(x[2])]; 158 t[1] = z[1] = x[2] ^ cast_sbox5[U_INT8_Ta(z[0])] ^ 159 cast_sbox6[U_INT8_Tc(z[0])] ^ 160 cast_sbox7[U_INT8_Tb(z[0])] ^ 161 cast_sbox8[U_INT8_Td(z[0])] ^ 162 cast_sbox8[U_INT8_Tc(x[2])]; 163 t[2] = z[2] = x[3] ^ cast_sbox5[U_INT8_Td(z[1])] ^ 164 cast_sbox6[U_INT8_Tc(z[1])] ^ 165 cast_sbox7[U_INT8_Tb(z[1])] ^ 166 cast_sbox8[U_INT8_Ta(z[1])] ^ 167 cast_sbox5[U_INT8_Tb(x[2])]; 168 t[3] = z[3] = x[1] ^ cast_sbox5[U_INT8_Tc(z[2])] ^ 169 cast_sbox6[U_INT8_Tb(z[2])] ^ 170 cast_sbox7[U_INT8_Td(z[2])] ^ 171 cast_sbox8[U_INT8_Ta(z[2])] ^ 172 cast_sbox6[U_INT8_Td(x[2])]; 173 break; 174 case 4: 175 t[0] = x[0] = z[2] ^ cast_sbox5[U_INT8_Tb(z[1])] ^ 176 cast_sbox6[U_INT8_Td(z[1])] ^ 177 cast_sbox7[U_INT8_Ta(z[1])] ^ 178 cast_sbox8[U_INT8_Tc(z[1])] ^ 179 cast_sbox7[U_INT8_Ta(z[0])]; 180 t[1] = x[1] = z[0] ^ cast_sbox5[U_INT8_Ta(x[0])] ^ 181 cast_sbox6[U_INT8_Tc(x[0])] ^ 182 cast_sbox7[U_INT8_Tb(x[0])] ^ 183 cast_sbox8[U_INT8_Td(x[0])] ^ 184 cast_sbox8[U_INT8_Tc(z[0])]; 185 t[2] = x[2] = z[1] ^ cast_sbox5[U_INT8_Td(x[1])] ^ 186 cast_sbox6[U_INT8_Tc(x[1])] ^ 187 cast_sbox7[U_INT8_Tb(x[1])] ^ 188 cast_sbox8[U_INT8_Ta(x[1])] ^ 189 cast_sbox5[U_INT8_Tb(z[0])]; 190 t[3] = x[3] = z[3] ^ cast_sbox5[U_INT8_Tc(x[2])] ^ 191 cast_sbox6[U_INT8_Tb(x[2])] ^ 192 cast_sbox7[U_INT8_Td(x[2])] ^ 193 cast_sbox8[U_INT8_Ta(x[2])] ^ 194 cast_sbox6[U_INT8_Td(z[0])]; 195 break; 196 } 197 switch (i & 12) { 198 case 0: 199 case 12: 200 key->xkey[i+0] = cast_sbox5[U_INT8_Ta(t[2])] ^ 201 cast_sbox6[U_INT8_Tb(t[2])] ^ 202 cast_sbox7[U_INT8_Td(t[1])] ^ 203 cast_sbox8[U_INT8_Tc(t[1])]; 204 key->xkey[i+1] = cast_sbox5[U_INT8_Tc(t[2])] ^ 205 cast_sbox6[U_INT8_Td(t[2])] ^ 206 cast_sbox7[U_INT8_Tb(t[1])] ^ 207 cast_sbox8[U_INT8_Ta(t[1])]; 208 key->xkey[i+2] = cast_sbox5[U_INT8_Ta(t[3])] ^ 209 cast_sbox6[U_INT8_Tb(t[3])] ^ 210 cast_sbox7[U_INT8_Td(t[0])] ^ 211 cast_sbox8[U_INT8_Tc(t[0])]; 212 key->xkey[i+3] = cast_sbox5[U_INT8_Tc(t[3])] ^ 213 cast_sbox6[U_INT8_Td(t[3])] ^ 214 cast_sbox7[U_INT8_Tb(t[0])] ^ 215 cast_sbox8[U_INT8_Ta(t[0])]; 216 break; 217 case 4: 218 case 8: 219 key->xkey[i+0] = cast_sbox5[U_INT8_Td(t[0])] ^ 220 cast_sbox6[U_INT8_Tc(t[0])] ^ 221 cast_sbox7[U_INT8_Ta(t[3])] ^ 222 cast_sbox8[U_INT8_Tb(t[3])]; 223 key->xkey[i+1] = cast_sbox5[U_INT8_Tb(t[0])] ^ 224 cast_sbox6[U_INT8_Ta(t[0])] ^ 225 cast_sbox7[U_INT8_Tc(t[3])] ^ 226 cast_sbox8[U_INT8_Td(t[3])]; 227 key->xkey[i+2] = cast_sbox5[U_INT8_Td(t[1])] ^ 228 cast_sbox6[U_INT8_Tc(t[1])] ^ 229 cast_sbox7[U_INT8_Ta(t[2])] ^ 230 cast_sbox8[U_INT8_Tb(t[2])]; 231 key->xkey[i+3] = cast_sbox5[U_INT8_Tb(t[1])] ^ 232 cast_sbox6[U_INT8_Ta(t[1])] ^ 233 cast_sbox7[U_INT8_Tc(t[2])] ^ 234 cast_sbox8[U_INT8_Td(t[2])]; 235 break; 236 } 237 switch (i & 12) { 238 case 0: 239 key->xkey[i+0] ^= cast_sbox5[U_INT8_Tc(z[0])]; 240 key->xkey[i+1] ^= cast_sbox6[U_INT8_Tc(z[1])]; 241 key->xkey[i+2] ^= cast_sbox7[U_INT8_Tb(z[2])]; 242 key->xkey[i+3] ^= cast_sbox8[U_INT8_Ta(z[3])]; 243 break; 244 case 4: 245 key->xkey[i+0] ^= cast_sbox5[U_INT8_Ta(x[2])]; 246 key->xkey[i+1] ^= cast_sbox6[U_INT8_Tb(x[3])]; 247 key->xkey[i+2] ^= cast_sbox7[U_INT8_Td(x[0])]; 248 key->xkey[i+3] ^= cast_sbox8[U_INT8_Td(x[1])]; 249 break; 250 case 8: 251 key->xkey[i+0] ^= cast_sbox5[U_INT8_Tb(z[2])]; 252 key->xkey[i+1] ^= cast_sbox6[U_INT8_Ta(z[3])]; 253 key->xkey[i+2] ^= cast_sbox7[U_INT8_Tc(z[0])]; 254 key->xkey[i+3] ^= cast_sbox8[U_INT8_Tc(z[1])]; 255 break; 256 case 12: 257 key->xkey[i+0] ^= cast_sbox5[U_INT8_Td(x[0])]; 258 key->xkey[i+1] ^= cast_sbox6[U_INT8_Td(x[1])]; 259 key->xkey[i+2] ^= cast_sbox7[U_INT8_Ta(x[2])]; 260 key->xkey[i+3] ^= cast_sbox8[U_INT8_Tb(x[3])]; 261 break; 262 } 263 if (i >= 16) { 264 key->xkey[i+0] &= 31; 265 key->xkey[i+1] &= 31; 266 key->xkey[i+2] &= 31; 267 key->xkey[i+3] &= 31; 268 } 269 } 270 /* Wipe clean */ 271 for (i = 0; i < 4; i++) { 272 t[i] = x[i] = z[i] = 0; 273 } 274 } 275 276 /* Made in Canada */ 277