Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/crypto/aes.c
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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 /* Some changes from the Gladman version: 51 s/RIJNDAEL(e_key)/E_KEY/g 52 s/RIJNDAEL(d_key)/D_KEY/g 53 */ 54 55 #include <linux/module.h> 56 #include <linux/init.h> 57 #include <linux/types.h> 58 #include <linux/errno.h> 59 #include <linux/crypto.h> 60 #include <asm/byteorder.h> 61 62 #define AES_MIN_KEY_SIZE 16 63 #define AES_MAX_KEY_SIZE 32 64 65 #define AES_BLOCK_SIZE 16 66 67 static inline 68 u32 generic_rotr32 (const u32 x, const unsigned bits) 69 { 70 const unsigned n = bits % 32; 71 return (x >> n) | (x << (32 - n)); 72 } 73 74 static inline 75 u32 generic_rotl32 (const u32 x, const unsigned bits) 76 { 77 const unsigned n = bits % 32; 78 return (x << n) | (x >> (32 - n)); 79 } 80 81 #define rotl generic_rotl32 82 #define rotr generic_rotr32 83 84 /* 85 * #define byte(x, nr) ((unsigned char)((x) >> (nr*8))) 86 */ 87 inline static u8 88 byte(const u32 x, const unsigned n) 89 { 90 return x >> (n << 3); 91 } 92 93 #define u32_in(x) le32_to_cpu(*(const u32 *)(x)) 94 #define u32_out(to, from) (*(u32 *)(to) = cpu_to_le32(from)) 95 96 struct aes_ctx { 97 int key_length; 98 u32 E[60]; 99 u32 D[60]; 100 }; 101 102 #define E_KEY ctx->E 103 #define D_KEY ctx->D 104 105 static u8 pow_tab[256]; 106 static u8 log_tab[256]; 107 static u8 sbx_tab[256]; 108 static u8 isb_tab[256]; 109 static u32 rco_tab[10]; 110 static u32 ft_tab[4][256]; 111 static u32 it_tab[4][256]; 112 113 static u32 fl_tab[4][256]; 114 static u32 il_tab[4][256]; 115 116 static inline u8 117 f_mult (u8 a, u8 b) 118 { 119 u8 aa = log_tab[a], cc = aa + log_tab[b]; 120 121 return pow_tab[cc + (cc < aa ? 1 : 0)]; 122 } 123 124 #define ff_mult(a,b) (a && b ? f_mult(a, b) : 0) 125 126 #define f_rn(bo, bi, n, k) \ 127 bo[n] = ft_tab[0][byte(bi[n],0)] ^ \ 128 ft_tab[1][byte(bi[(n + 1) & 3],1)] ^ \ 129 ft_tab[2][byte(bi[(n + 2) & 3],2)] ^ \ 130 ft_tab[3][byte(bi[(n + 3) & 3],3)] ^ *(k + n) 131 132 #define i_rn(bo, bi, n, k) \ 133 bo[n] = it_tab[0][byte(bi[n],0)] ^ \ 134 it_tab[1][byte(bi[(n + 3) & 3],1)] ^ \ 135 it_tab[2][byte(bi[(n + 2) & 3],2)] ^ \ 136 it_tab[3][byte(bi[(n + 1) & 3],3)] ^ *(k + n) 137 138 #define ls_box(x) \ 139 ( fl_tab[0][byte(x, 0)] ^ \ 140 fl_tab[1][byte(x, 1)] ^ \ 141 fl_tab[2][byte(x, 2)] ^ \ 142 fl_tab[3][byte(x, 3)] ) 143 144 #define f_rl(bo, bi, n, k) \ 145 bo[n] = fl_tab[0][byte(bi[n],0)] ^ \ 146 fl_tab[1][byte(bi[(n + 1) & 3],1)] ^ \ 147 fl_tab[2][byte(bi[(n + 2) & 3],2)] ^ \ 148 fl_tab[3][byte(bi[(n + 3) & 3],3)] ^ *(k + n) 149 150 #define i_rl(bo, bi, n, k) \ 151 bo[n] = il_tab[0][byte(bi[n],0)] ^ \ 152 il_tab[1][byte(bi[(n + 3) & 3],1)] ^ \ 153 il_tab[2][byte(bi[(n + 2) & 3],2)] ^ \ 154 il_tab[3][byte(bi[(n + 1) & 3],3)] ^ *(k + n) 155 156 static void 157 gen_tabs (void) 158 { 159 u32 i, t; 160 u8 p, q; 161 162 /* log and power tables for GF(2**8) finite field with 163 0x011b as modular polynomial - the simplest prmitive 164 root is 0x03, used here to generate the tables */ 165 166 for (i = 0, p = 1; i < 256; ++i) { 167 pow_tab[i] = (u8) p; 168 log_tab[p] = (u8) i; 169 170 p ^= (p << 1) ^ (p & 0x80 ? 0x01b : 0); 171 } 172 173 log_tab[1] = 0; 174 175 for (i = 0, p = 1; i < 10; ++i) { 176 rco_tab[i] = p; 177 178 p = (p << 1) ^ (p & 0x80 ? 0x01b : 0); 179 } 180 181 for (i = 0; i < 256; ++i) { 182 p = (i ? pow_tab[255 - log_tab[i]] : 0); 183 q = ((p >> 7) | (p << 1)) ^ ((p >> 6) | (p << 2)); 184 p ^= 0x63 ^ q ^ ((q >> 6) | (q << 2)); 185 sbx_tab[i] = p; 186 isb_tab[p] = (u8) i; 187 } 188 189 for (i = 0; i < 256; ++i) { 190 p = sbx_tab[i]; 191 192 t = p; 193 fl_tab[0][i] = t; 194 fl_tab[1][i] = rotl (t, 8); 195 fl_tab[2][i] = rotl (t, 16); 196 fl_tab[3][i] = rotl (t, 24); 197 198 t = ((u32) ff_mult (2, p)) | 199 ((u32) p << 8) | 200 ((u32) p << 16) | ((u32) ff_mult (3, p) << 24); 201 202 ft_tab[0][i] = t; 203 ft_tab[1][i] = rotl (t, 8); 204 ft_tab[2][i] = rotl (t, 16); 205 ft_tab[3][i] = rotl (t, 24); 206 207 p = isb_tab[i]; 208 209 t = p; 210 il_tab[0][i] = t; 211 il_tab[1][i] = rotl (t, 8); 212 il_tab[2][i] = rotl (t, 16); 213 il_tab[3][i] = rotl (t, 24); 214 215 t = ((u32) ff_mult (14, p)) | 216 ((u32) ff_mult (9, p) << 8) | 217 ((u32) ff_mult (13, p) << 16) | 218 ((u32) ff_mult (11, p) << 24); 219 220 it_tab[0][i] = t; 221 it_tab[1][i] = rotl (t, 8); 222 it_tab[2][i] = rotl (t, 16); 223 it_tab[3][i] = rotl (t, 24); 224 } 225 } 226 227 #define star_x(x) (((x) & 0x7f7f7f7f) << 1) ^ ((((x) & 0x80808080) >> 7) * 0x1b) 228 229 #define imix_col(y,x) \ 230 u = star_x(x); \ 231 v = star_x(u); \ 232 w = star_x(v); \ 233 t = w ^ (x); \ 234 (y) = u ^ v ^ w; \ 235 (y) ^= rotr(u ^ t, 8) ^ \ 236 rotr(v ^ t, 16) ^ \ 237 rotr(t,24) 238 239 /* initialise the key schedule from the user supplied key */ 240 241 #define loop4(i) \ 242 { t = rotr(t, 8); t = ls_box(t) ^ rco_tab[i]; \ 243 t ^= E_KEY[4 * i]; E_KEY[4 * i + 4] = t; \ 244 t ^= E_KEY[4 * i + 1]; E_KEY[4 * i + 5] = t; \ 245 t ^= E_KEY[4 * i + 2]; E_KEY[4 * i + 6] = t; \ 246 t ^= E_KEY[4 * i + 3]; E_KEY[4 * i + 7] = t; \ 247 } 248 249 #define loop6(i) \ 250 { t = rotr(t, 8); t = ls_box(t) ^ rco_tab[i]; \ 251 t ^= E_KEY[6 * i]; E_KEY[6 * i + 6] = t; \ 252 t ^= E_KEY[6 * i + 1]; E_KEY[6 * i + 7] = t; \ 253 t ^= E_KEY[6 * i + 2]; E_KEY[6 * i + 8] = t; \ 254 t ^= E_KEY[6 * i + 3]; E_KEY[6 * i + 9] = t; \ 255 t ^= E_KEY[6 * i + 4]; E_KEY[6 * i + 10] = t; \ 256 t ^= E_KEY[6 * i + 5]; E_KEY[6 * i + 11] = t; \ 257 } 258 259 #define loop8(i) \ 260 { t = rotr(t, 8); ; t = ls_box(t) ^ rco_tab[i]; \ 261 t ^= E_KEY[8 * i]; E_KEY[8 * i + 8] = t; \ 262 t ^= E_KEY[8 * i + 1]; E_KEY[8 * i + 9] = t; \ 263 t ^= E_KEY[8 * i + 2]; E_KEY[8 * i + 10] = t; \ 264 t ^= E_KEY[8 * i + 3]; E_KEY[8 * i + 11] = t; \ 265 t = E_KEY[8 * i + 4] ^ ls_box(t); \ 266 E_KEY[8 * i + 12] = t; \ 267 t ^= E_KEY[8 * i + 5]; E_KEY[8 * i + 13] = t; \ 268 t ^= E_KEY[8 * i + 6]; E_KEY[8 * i + 14] = t; \ 269 t ^= E_KEY[8 * i + 7]; E_KEY[8 * i + 15] = t; \ 270 } 271 272 static int 273 aes_set_key(void *ctx_arg, const u8 *in_key, unsigned int key_len, u32 *flags) 274 { 275 struct aes_ctx *ctx = ctx_arg; 276 u32 i, t, u, v, w; 277 278 if (key_len != 16 && key_len != 24 && key_len != 32) { 279 *flags |= CRYPTO_TFM_RES_BAD_KEY_LEN; 280 return -EINVAL; 281 } 282 283 ctx->key_length = key_len; 284 285 E_KEY[0] = u32_in (in_key); 286 E_KEY[1] = u32_in (in_key + 4); 287 E_KEY[2] = u32_in (in_key + 8); 288 E_KEY[3] = u32_in (in_key + 12); 289 290 switch (key_len) { 291 case 16: 292 t = E_KEY[3]; 293 for (i = 0; i < 10; ++i) 294 loop4 (i); 295 break; 296 297 case 24: 298 E_KEY[4] = u32_in (in_key + 16); 299 t = E_KEY[5] = u32_in (in_key + 20); 300 for (i = 0; i < 8; ++i) 301 loop6 (i); 302 break; 303 304 case 32: 305 E_KEY[4] = u32_in (in_key + 16); 306 E_KEY[5] = u32_in (in_key + 20); 307 E_KEY[6] = u32_in (in_key + 24); 308 t = E_KEY[7] = u32_in (in_key + 28); 309 for (i = 0; i < 7; ++i) 310 loop8 (i); 311 break; 312 } 313 314 D_KEY[0] = E_KEY[0]; 315 D_KEY[1] = E_KEY[1]; 316 D_KEY[2] = E_KEY[2]; 317 D_KEY[3] = E_KEY[3]; 318 319 for (i = 4; i < key_len + 24; ++i) { 320 imix_col (D_KEY[i], E_KEY[i]); 321 } 322 323 return 0; 324 } 325 326 /* encrypt a block of text */ 327 328 #define f_nround(bo, bi, k) \ 329 f_rn(bo, bi, 0, k); \ 330 f_rn(bo, bi, 1, k); \ 331 f_rn(bo, bi, 2, k); \ 332 f_rn(bo, bi, 3, k); \ 333 k += 4 334 335 #define f_lround(bo, bi, k) \ 336 f_rl(bo, bi, 0, k); \ 337 f_rl(bo, bi, 1, k); \ 338 f_rl(bo, bi, 2, k); \ 339 f_rl(bo, bi, 3, k) 340 341 static void aes_encrypt(void *ctx_arg, u8 *out, const u8 *in) 342 { 343 const struct aes_ctx *ctx = ctx_arg; 344 u32 b0[4], b1[4]; 345 const u32 *kp = E_KEY + 4; 346 347 b0[0] = u32_in (in) ^ E_KEY[0]; 348 b0[1] = u32_in (in + 4) ^ E_KEY[1]; 349 b0[2] = u32_in (in + 8) ^ E_KEY[2]; 350 b0[3] = u32_in (in + 12) ^ E_KEY[3]; 351 352 if (ctx->key_length > 24) { 353 f_nround (b1, b0, kp); 354 f_nround (b0, b1, kp); 355 } 356 357 if (ctx->key_length > 16) { 358 f_nround (b1, b0, kp); 359 f_nround (b0, b1, kp); 360 } 361 362 f_nround (b1, b0, kp); 363 f_nround (b0, b1, kp); 364 f_nround (b1, b0, kp); 365 f_nround (b0, b1, kp); 366 f_nround (b1, b0, kp); 367 f_nround (b0, b1, kp); 368 f_nround (b1, b0, kp); 369 f_nround (b0, b1, kp); 370 f_nround (b1, b0, kp); 371 f_lround (b0, b1, kp); 372 373 u32_out (out, b0[0]); 374 u32_out (out + 4, b0[1]); 375 u32_out (out + 8, b0[2]); 376 u32_out (out + 12, b0[3]); 377 } 378 379 /* decrypt a block of text */ 380 381 #define i_nround(bo, bi, k) \ 382 i_rn(bo, bi, 0, k); \ 383 i_rn(bo, bi, 1, k); \ 384 i_rn(bo, bi, 2, k); \ 385 i_rn(bo, bi, 3, k); \ 386 k -= 4 387 388 #define i_lround(bo, bi, k) \ 389 i_rl(bo, bi, 0, k); \ 390 i_rl(bo, bi, 1, k); \ 391 i_rl(bo, bi, 2, k); \ 392 i_rl(bo, bi, 3, k) 393 394 static void aes_decrypt(void *ctx_arg, u8 *out, const u8 *in) 395 { 396 const struct aes_ctx *ctx = ctx_arg; 397 u32 b0[4], b1[4]; 398 const int key_len = ctx->key_length; 399 const u32 *kp = D_KEY + key_len + 20; 400 401 b0[0] = u32_in (in) ^ E_KEY[key_len + 24]; 402 b0[1] = u32_in (in + 4) ^ E_KEY[key_len + 25]; 403 b0[2] = u32_in (in + 8) ^ E_KEY[key_len + 26]; 404 b0[3] = u32_in (in + 12) ^ E_KEY[key_len + 27]; 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 u32_out (out, b0[0]); 428 u32_out (out + 4, b0[1]); 429 u32_out (out + 8, b0[2]); 430 u32_out (out + 12, b0[3]); 431 } 432 433 434 static struct crypto_alg aes_alg = { 435 .cra_name = "aes", 436 .cra_flags = CRYPTO_ALG_TYPE_CIPHER, 437 .cra_blocksize = AES_BLOCK_SIZE, 438 .cra_ctxsize = sizeof(struct aes_ctx), 439 .cra_module = THIS_MODULE, 440 .cra_list = LIST_HEAD_INIT(aes_alg.cra_list), 441 .cra_u = { 442 .cipher = { 443 .cia_min_keysize = AES_MIN_KEY_SIZE, 444 .cia_max_keysize = AES_MAX_KEY_SIZE, 445 .cia_ivsize = AES_BLOCK_SIZE, 446 .cia_setkey = aes_set_key, 447 .cia_encrypt = aes_encrypt, 448 .cia_decrypt = aes_decrypt 449 } 450 } 451 }; 452 453 static int __init aes_init(void) 454 { 455 gen_tabs(); 456 return crypto_register_alg(&aes_alg); 457 } 458 459 static void __exit aes_fini(void) 460 { 461 crypto_unregister_alg(&aes_alg); 462 } 463 464 module_init(aes_init); 465 module_exit(aes_fini); 466 467 MODULE_DESCRIPTION("Rijndael (AES) Cipher Algorithm"); 468 MODULE_LICENSE("Dual BSD/GPL"); 469
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