1 /* 2 * Cryptographic API. 3 * 4 * AES Cipher Algorithm. 5 * 6 * Based on Brian Gladman's code. 7 * 8 * Linux developers: 9 * Alexander Kjeldaas <astor@fast.no> 10 * Herbert Valerio Riedel <hvr@hvrlab.org> 11 * Kyle McMartin <kyle@debian.org> 12 * Adam J. Richter <adam@yggdrasil.com> (conversion to 2.5 API). 13 * 14 * This program is free software; you can redistribute it and/or modify 15 * it under the terms of the GNU General Public License as published by 16 * the Free Software Foundation; either version 2 of the License, or 17 * (at your option) any later version. 18 * 19 * --------------------------------------------------------------------------- 20 * Copyright (c) 2002, Dr Brian Gladman <brg@gladman.me.uk>, Worcester, UK. 21 * All rights reserved. 22 * 23 * LICENSE TERMS 24 * 25 * The free distribution and use of this software in both source and binary 26 * form is allowed (with or without changes) provided that: 27 * 28 * 1. distributions of this source code include the above copyright 29 * notice, this list of conditions and the following disclaimer; 30 * 31 * 2. distributions in binary form include the above copyright 32 * notice, this list of conditions and the following disclaimer 33 * in the documentation and/or other associated materials; 34 * 35 * 3. the copyright holder's name is not used to endorse products 36 * built using this software without specific written permission. 37 * 38 * ALTERNATIVELY, provided that this notice is retained in full, this product 39 * may be distributed under the terms of the GNU General Public License (GPL), 40 * in which case the provisions of the GPL apply INSTEAD OF those given above. 41 * 42 * DISCLAIMER 43 * 44 * This software is provided 'as is' with no explicit or implied warranties 45 * in respect of its properties, including, but not limited to, correctness 46 * and/or fitness for purpose. 47 * --------------------------------------------------------------------------- 48 */ 49 50 #include <crypto/aes.h> 51 #include <linux/module.h> 52 #include <linux/init.h> 53 #include <linux/types.h> 54 #include <linux/errno.h> 55 #include <linux/crypto.h> 56 #include <asm/byteorder.h> 57 58 static inline u8 byte(const u32 x, const unsigned n) 59 { 60 return x >> (n << 3); 61 } 62 63 static u8 pow_tab[256] __initdata; 64 static u8 log_tab[256] __initdata; 65 static u8 sbx_tab[256] __initdata; 66 static u8 isb_tab[256] __initdata; 67 static u32 rco_tab[10]; 68 69 u32 crypto_ft_tab[4][256]; 70 u32 crypto_fl_tab[4][256]; 71 u32 crypto_it_tab[4][256]; 72 u32 crypto_il_tab[4][256]; 73 74 EXPORT_SYMBOL_GPL(crypto_ft_tab); 75 EXPORT_SYMBOL_GPL(crypto_fl_tab); 76 EXPORT_SYMBOL_GPL(crypto_it_tab); 77 EXPORT_SYMBOL_GPL(crypto_il_tab); 78 79 static inline u8 __init f_mult(u8 a, u8 b) 80 { 81 u8 aa = log_tab[a], cc = aa + log_tab[b]; 82 83 return pow_tab[cc + (cc < aa ? 1 : 0)]; 84 } 85 86 #define ff_mult(a, b) (a && b ? f_mult(a, b) : 0) 87 88 static void __init gen_tabs(void) 89 { 90 u32 i, t; 91 u8 p, q; 92 93 /* 94 * log and power tables for GF(2**8) finite field with 95 * 0x011b as modular polynomial - the simplest primitive 96 * root is 0x03, used here to generate the tables 97 */ 98 99 for (i = 0, p = 1; i < 256; ++i) { 100 pow_tab[i] = (u8) p; 101 log_tab[p] = (u8) i; 102 103 p ^= (p << 1) ^ (p & 0x80 ? 0x01b : 0); 104 } 105 106 log_tab[1] = 0; 107 108 for (i = 0, p = 1; i < 10; ++i) { 109 rco_tab[i] = p; 110 111 p = (p << 1) ^ (p & 0x80 ? 0x01b : 0); 112 } 113 114 for (i = 0; i < 256; ++i) { 115 p = (i ? pow_tab[255 - log_tab[i]] : 0); 116 q = ((p >> 7) | (p << 1)) ^ ((p >> 6) | (p << 2)); 117 p ^= 0x63 ^ q ^ ((q >> 6) | (q << 2)); 118 sbx_tab[i] = p; 119 isb_tab[p] = (u8) i; 120 } 121 122 for (i = 0; i < 256; ++i) { 123 p = sbx_tab[i]; 124 125 t = p; 126 crypto_fl_tab[0][i] = t; 127 crypto_fl_tab[1][i] = rol32(t, 8); 128 crypto_fl_tab[2][i] = rol32(t, 16); 129 crypto_fl_tab[3][i] = rol32(t, 24); 130 131 t = ((u32) ff_mult(2, p)) | 132 ((u32) p << 8) | 133 ((u32) p << 16) | ((u32) ff_mult(3, p) << 24); 134 135 crypto_ft_tab[0][i] = t; 136 crypto_ft_tab[1][i] = rol32(t, 8); 137 crypto_ft_tab[2][i] = rol32(t, 16); 138 crypto_ft_tab[3][i] = rol32(t, 24); 139 140 p = isb_tab[i]; 141 142 t = p; 143 crypto_il_tab[0][i] = t; 144 crypto_il_tab[1][i] = rol32(t, 8); 145 crypto_il_tab[2][i] = rol32(t, 16); 146 crypto_il_tab[3][i] = rol32(t, 24); 147 148 t = ((u32) ff_mult(14, p)) | 149 ((u32) ff_mult(9, p) << 8) | 150 ((u32) ff_mult(13, p) << 16) | 151 ((u32) ff_mult(11, p) << 24); 152 153 crypto_it_tab[0][i] = t; 154 crypto_it_tab[1][i] = rol32(t, 8); 155 crypto_it_tab[2][i] = rol32(t, 16); 156 crypto_it_tab[3][i] = rol32(t, 24); 157 } 158 } 159 160 /* initialise the key schedule from the user supplied key */ 161 162 #define star_x(x) (((x) & 0x7f7f7f7f) << 1) ^ ((((x) & 0x80808080) >> 7) * 0x1b) 163 164 #define imix_col(y,x) do { \ 165 u = star_x(x); \ 166 v = star_x(u); \ 167 w = star_x(v); \ 168 t = w ^ (x); \ 169 (y) = u ^ v ^ w; \ 170 (y) ^= ror32(u ^ t, 8) ^ \ 171 ror32(v ^ t, 16) ^ \ 172 ror32(t, 24); \ 173 } while (0) 174 175 #define ls_box(x) \ 176 crypto_fl_tab[0][byte(x, 0)] ^ \ 177 crypto_fl_tab[1][byte(x, 1)] ^ \ 178 crypto_fl_tab[2][byte(x, 2)] ^ \ 179 crypto_fl_tab[3][byte(x, 3)] 180 181 #define loop4(i) do { \ 182 t = ror32(t, 8); \ 183 t = ls_box(t) ^ rco_tab[i]; \ 184 t ^= ctx->key_enc[4 * i]; \ 185 ctx->key_enc[4 * i + 4] = t; \ 186 t ^= ctx->key_enc[4 * i + 1]; \ 187 ctx->key_enc[4 * i + 5] = t; \ 188 t ^= ctx->key_enc[4 * i + 2]; \ 189 ctx->key_enc[4 * i + 6] = t; \ 190 t ^= ctx->key_enc[4 * i + 3]; \ 191 ctx->key_enc[4 * i + 7] = t; \ 192 } while (0) 193 194 #define loop6(i) do { \ 195 t = ror32(t, 8); \ 196 t = ls_box(t) ^ rco_tab[i]; \ 197 t ^= ctx->key_enc[6 * i]; \ 198 ctx->key_enc[6 * i + 6] = t; \ 199 t ^= ctx->key_enc[6 * i + 1]; \ 200 ctx->key_enc[6 * i + 7] = t; \ 201 t ^= ctx->key_enc[6 * i + 2]; \ 202 ctx->key_enc[6 * i + 8] = t; \ 203 t ^= ctx->key_enc[6 * i + 3]; \ 204 ctx->key_enc[6 * i + 9] = t; \ 205 t ^= ctx->key_enc[6 * i + 4]; \ 206 ctx->key_enc[6 * i + 10] = t; \ 207 t ^= ctx->key_enc[6 * i + 5]; \ 208 ctx->key_enc[6 * i + 11] = t; \ 209 } while (0) 210 211 #define loop8(i) do { \ 212 t = ror32(t, 8); \ 213 t = ls_box(t) ^ rco_tab[i]; \ 214 t ^= ctx->key_enc[8 * i]; \ 215 ctx->key_enc[8 * i + 8] = t; \ 216 t ^= ctx->key_enc[8 * i + 1]; \ 217 ctx->key_enc[8 * i + 9] = t; \ 218 t ^= ctx->key_enc[8 * i + 2]; \ 219 ctx->key_enc[8 * i + 10] = t; \ 220 t ^= ctx->key_enc[8 * i + 3]; \ 221 ctx->key_enc[8 * i + 11] = t; \ 222 t = ctx->key_enc[8 * i + 4] ^ ls_box(t); \ 223 ctx->key_enc[8 * i + 12] = t; \ 224 t ^= ctx->key_enc[8 * i + 5]; \ 225 ctx->key_enc[8 * i + 13] = t; \ 226 t ^= ctx->key_enc[8 * i + 6]; \ 227 ctx->key_enc[8 * i + 14] = t; \ 228 t ^= ctx->key_enc[8 * i + 7]; \ 229 ctx->key_enc[8 * i + 15] = t; \ 230 } while (0) 231 232 int crypto_aes_set_key(struct crypto_tfm *tfm, const u8 *in_key, 233 unsigned int key_len) 234 { 235 struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm); 236 const __le32 *key = (const __le32 *)in_key; 237 u32 *flags = &tfm->crt_flags; 238 u32 i, t, u, v, w, j; 239 240 if (key_len % 8) { 241 *flags |= CRYPTO_TFM_RES_BAD_KEY_LEN; 242 return -EINVAL; 243 } 244 245 ctx->key_length = key_len; 246 247 ctx->key_dec[key_len + 24] = ctx->key_enc[0] = le32_to_cpu(key[0]); 248 ctx->key_dec[key_len + 25] = ctx->key_enc[1] = le32_to_cpu(key[1]); 249 ctx->key_dec[key_len + 26] = ctx->key_enc[2] = le32_to_cpu(key[2]); 250 ctx->key_dec[key_len + 27] = ctx->key_enc[3] = le32_to_cpu(key[3]); 251 252 switch (key_len) { 253 case 16: 254 t = ctx->key_enc[3]; 255 for (i = 0; i < 10; ++i) 256 loop4(i); 257 break; 258 259 case 24: 260 ctx->key_enc[4] = le32_to_cpu(key[4]); 261 t = ctx->key_enc[5] = le32_to_cpu(key[5]); 262 for (i = 0; i < 8; ++i) 263 loop6(i); 264 break; 265 266 case 32: 267 ctx->key_enc[4] = le32_to_cpu(key[4]); 268 ctx->key_enc[5] = le32_to_cpu(key[5]); 269 ctx->key_enc[6] = le32_to_cpu(key[6]); 270 t = ctx->key_enc[7] = le32_to_cpu(key[7]); 271 for (i = 0; i < 7; ++i) 272 loop8(i); 273 break; 274 } 275 276 ctx->key_dec[0] = ctx->key_enc[key_len + 24]; 277 ctx->key_dec[1] = ctx->key_enc[key_len + 25]; 278 ctx->key_dec[2] = ctx->key_enc[key_len + 26]; 279 ctx->key_dec[3] = ctx->key_enc[key_len + 27]; 280 281 for (i = 4; i < key_len + 24; ++i) { 282 j = key_len + 24 - (i & ~3) + (i & 3); 283 imix_col(ctx->key_dec[j], ctx->key_enc[i]); 284 } 285 return 0; 286 } 287 EXPORT_SYMBOL_GPL(crypto_aes_set_key); 288 289 /* encrypt a block of text */ 290 291 #define f_rn(bo, bi, n, k) do { \ 292 bo[n] = crypto_ft_tab[0][byte(bi[n], 0)] ^ \ 293 crypto_ft_tab[1][byte(bi[(n + 1) & 3], 1)] ^ \ 294 crypto_ft_tab[2][byte(bi[(n + 2) & 3], 2)] ^ \ 295 crypto_ft_tab[3][byte(bi[(n + 3) & 3], 3)] ^ *(k + n); \ 296 } while (0) 297 298 #define f_nround(bo, bi, k) do {\ 299 f_rn(bo, bi, 0, k); \ 300 f_rn(bo, bi, 1, k); \ 301 f_rn(bo, bi, 2, k); \ 302 f_rn(bo, bi, 3, k); \ 303 k += 4; \ 304 } while (0) 305 306 #define f_rl(bo, bi, n, k) do { \ 307 bo[n] = crypto_fl_tab[0][byte(bi[n], 0)] ^ \ 308 crypto_fl_tab[1][byte(bi[(n + 1) & 3], 1)] ^ \ 309 crypto_fl_tab[2][byte(bi[(n + 2) & 3], 2)] ^ \ 310 crypto_fl_tab[3][byte(bi[(n + 3) & 3], 3)] ^ *(k + n); \ 311 } while (0) 312 313 #define f_lround(bo, bi, k) do {\ 314 f_rl(bo, bi, 0, k); \ 315 f_rl(bo, bi, 1, k); \ 316 f_rl(bo, bi, 2, k); \ 317 f_rl(bo, bi, 3, k); \ 318 } while (0) 319 320 static void aes_encrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in) 321 { 322 const struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm); 323 const __le32 *src = (const __le32 *)in; 324 __le32 *dst = (__le32 *)out; 325 u32 b0[4], b1[4]; 326 const u32 *kp = ctx->key_enc + 4; 327 const int key_len = ctx->key_length; 328 329 b0[0] = le32_to_cpu(src[0]) ^ ctx->key_enc[0]; 330 b0[1] = le32_to_cpu(src[1]) ^ ctx->key_enc[1]; 331 b0[2] = le32_to_cpu(src[2]) ^ ctx->key_enc[2]; 332 b0[3] = le32_to_cpu(src[3]) ^ ctx->key_enc[3]; 333 334 if (key_len > 24) { 335 f_nround(b1, b0, kp); 336 f_nround(b0, b1, kp); 337 } 338 339 if (key_len > 16) { 340 f_nround(b1, b0, kp); 341 f_nround(b0, b1, kp); 342 } 343 344 f_nround(b1, b0, kp); 345 f_nround(b0, b1, kp); 346 f_nround(b1, b0, kp); 347 f_nround(b0, b1, kp); 348 f_nround(b1, b0, kp); 349 f_nround(b0, b1, kp); 350 f_nround(b1, b0, kp); 351 f_nround(b0, b1, kp); 352 f_nround(b1, b0, kp); 353 f_lround(b0, b1, kp); 354 355 dst[0] = cpu_to_le32(b0[0]); 356 dst[1] = cpu_to_le32(b0[1]); 357 dst[2] = cpu_to_le32(b0[2]); 358 dst[3] = cpu_to_le32(b0[3]); 359 } 360 361 /* decrypt a block of text */ 362 363 #define i_rn(bo, bi, n, k) do { \ 364 bo[n] = crypto_it_tab[0][byte(bi[n], 0)] ^ \ 365 crypto_it_tab[1][byte(bi[(n + 3) & 3], 1)] ^ \ 366 crypto_it_tab[2][byte(bi[(n + 2) & 3], 2)] ^ \ 367 crypto_it_tab[3][byte(bi[(n + 1) & 3], 3)] ^ *(k + n); \ 368 } while (0) 369 370 #define i_nround(bo, bi, k) do {\ 371 i_rn(bo, bi, 0, k); \ 372 i_rn(bo, bi, 1, k); \ 373 i_rn(bo, bi, 2, k); \ 374 i_rn(bo, bi, 3, k); \ 375 k += 4; \ 376 } while (0) 377 378 #define i_rl(bo, bi, n, k) do { \ 379 bo[n] = crypto_il_tab[0][byte(bi[n], 0)] ^ \ 380 crypto_il_tab[1][byte(bi[(n + 3) & 3], 1)] ^ \ 381 crypto_il_tab[2][byte(bi[(n + 2) & 3], 2)] ^ \ 382 crypto_il_tab[3][byte(bi[(n + 1) & 3], 3)] ^ *(k + n); \ 383 } while (0) 384 385 #define i_lround(bo, bi, k) do {\ 386 i_rl(bo, bi, 0, k); \ 387 i_rl(bo, bi, 1, k); \ 388 i_rl(bo, bi, 2, k); \ 389 i_rl(bo, bi, 3, k); \ 390 } while (0) 391 392 static void aes_decrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in) 393 { 394 const struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm); 395 const __le32 *src = (const __le32 *)in; 396 __le32 *dst = (__le32 *)out; 397 u32 b0[4], b1[4]; 398 const int key_len = ctx->key_length; 399 const u32 *kp = ctx->key_dec + 4; 400 401 b0[0] = le32_to_cpu(src[0]) ^ ctx->key_dec[0]; 402 b0[1] = le32_to_cpu(src[1]) ^ ctx->key_dec[1]; 403 b0[2] = le32_to_cpu(src[2]) ^ ctx->key_dec[2]; 404 b0[3] = le32_to_cpu(src[3]) ^ ctx->key_dec[3]; 405 406 if (key_len > 24) { 407 i_nround(b1, b0, kp); 408 i_nround(b0, b1, kp); 409 } 410 411 if (key_len > 16) { 412 i_nround(b1, b0, kp); 413 i_nround(b0, b1, kp); 414 } 415 416 i_nround(b1, b0, kp); 417 i_nround(b0, b1, kp); 418 i_nround(b1, b0, kp); 419 i_nround(b0, b1, kp); 420 i_nround(b1, b0, kp); 421 i_nround(b0, b1, kp); 422 i_nround(b1, b0, kp); 423 i_nround(b0, b1, kp); 424 i_nround(b1, b0, kp); 425 i_lround(b0, b1, kp); 426 427 dst[0] = cpu_to_le32(b0[0]); 428 dst[1] = cpu_to_le32(b0[1]); 429 dst[2] = cpu_to_le32(b0[2]); 430 dst[3] = cpu_to_le32(b0[3]); 431 } 432 433 static struct crypto_alg aes_alg = { 434 .cra_name = "aes", 435 .cra_driver_name = "aes-generic", 436 .cra_priority = 100, 437 .cra_flags = CRYPTO_ALG_TYPE_CIPHER, 438 .cra_blocksize = AES_BLOCK_SIZE, 439 .cra_ctxsize = sizeof(struct crypto_aes_ctx), 440 .cra_alignmask = 3, 441 .cra_module = THIS_MODULE, 442 .cra_list = LIST_HEAD_INIT(aes_alg.cra_list), 443 .cra_u = { 444 .cipher = { 445 .cia_min_keysize = AES_MIN_KEY_SIZE, 446 .cia_max_keysize = AES_MAX_KEY_SIZE, 447 .cia_setkey = crypto_aes_set_key, 448 .cia_encrypt = aes_encrypt, 449 .cia_decrypt = aes_decrypt 450 } 451 } 452 }; 453 454 static int __init aes_init(void) 455 { 456 gen_tabs(); 457 return crypto_register_alg(&aes_alg); 458 } 459 460 static void __exit aes_fini(void) 461 { 462 crypto_unregister_alg(&aes_alg); 463 } 464 465 module_init(aes_init); 466 module_exit(aes_fini); 467 468 MODULE_DESCRIPTION("Rijndael (AES) Cipher Algorithm"); 469 MODULE_LICENSE("Dual BSD/GPL"); 470 MODULE_ALIAS("aes"); 471