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 /* 68 * #define byte(x, nr) ((unsigned char)((x) >> (nr*8))) 69 */ 70 static inline u8 71 byte(const u32 x, const unsigned n) 72 { 73 return x >> (n << 3); 74 } 75 76 struct aes_ctx { 77 int key_length; 78 u32 buf[120]; 79 }; 80 81 #define E_KEY (&ctx->buf[0]) 82 #define D_KEY (&ctx->buf[60]) 83 84 static u8 pow_tab[256] __initdata; 85 static u8 log_tab[256] __initdata; 86 static u8 sbx_tab[256] __initdata; 87 static u8 isb_tab[256] __initdata; 88 static u32 rco_tab[10]; 89 static u32 ft_tab[4][256]; 90 static u32 it_tab[4][256]; 91 92 static u32 fl_tab[4][256]; 93 static u32 il_tab[4][256]; 94 95 static inline u8 __init 96 f_mult (u8 a, u8 b) 97 { 98 u8 aa = log_tab[a], cc = aa + log_tab[b]; 99 100 return pow_tab[cc + (cc < aa ? 1 : 0)]; 101 } 102 103 #define ff_mult(a,b) (a && b ? f_mult(a, b) : 0) 104 105 #define f_rn(bo, bi, n, k) \ 106 bo[n] = ft_tab[0][byte(bi[n],0)] ^ \ 107 ft_tab[1][byte(bi[(n + 1) & 3],1)] ^ \ 108 ft_tab[2][byte(bi[(n + 2) & 3],2)] ^ \ 109 ft_tab[3][byte(bi[(n + 3) & 3],3)] ^ *(k + n) 110 111 #define i_rn(bo, bi, n, k) \ 112 bo[n] = it_tab[0][byte(bi[n],0)] ^ \ 113 it_tab[1][byte(bi[(n + 3) & 3],1)] ^ \ 114 it_tab[2][byte(bi[(n + 2) & 3],2)] ^ \ 115 it_tab[3][byte(bi[(n + 1) & 3],3)] ^ *(k + n) 116 117 #define ls_box(x) \ 118 ( fl_tab[0][byte(x, 0)] ^ \ 119 fl_tab[1][byte(x, 1)] ^ \ 120 fl_tab[2][byte(x, 2)] ^ \ 121 fl_tab[3][byte(x, 3)] ) 122 123 #define f_rl(bo, bi, n, k) \ 124 bo[n] = fl_tab[0][byte(bi[n],0)] ^ \ 125 fl_tab[1][byte(bi[(n + 1) & 3],1)] ^ \ 126 fl_tab[2][byte(bi[(n + 2) & 3],2)] ^ \ 127 fl_tab[3][byte(bi[(n + 3) & 3],3)] ^ *(k + n) 128 129 #define i_rl(bo, bi, n, k) \ 130 bo[n] = il_tab[0][byte(bi[n],0)] ^ \ 131 il_tab[1][byte(bi[(n + 3) & 3],1)] ^ \ 132 il_tab[2][byte(bi[(n + 2) & 3],2)] ^ \ 133 il_tab[3][byte(bi[(n + 1) & 3],3)] ^ *(k + n) 134 135 static void __init 136 gen_tabs (void) 137 { 138 u32 i, t; 139 u8 p, q; 140 141 /* log and power tables for GF(2**8) finite field with 142 0x011b as modular polynomial - the simplest primitive 143 root is 0x03, used here to generate the tables */ 144 145 for (i = 0, p = 1; i < 256; ++i) { 146 pow_tab[i] = (u8) p; 147 log_tab[p] = (u8) i; 148 149 p ^= (p << 1) ^ (p & 0x80 ? 0x01b : 0); 150 } 151 152 log_tab[1] = 0; 153 154 for (i = 0, p = 1; i < 10; ++i) { 155 rco_tab[i] = p; 156 157 p = (p << 1) ^ (p & 0x80 ? 0x01b : 0); 158 } 159 160 for (i = 0; i < 256; ++i) { 161 p = (i ? pow_tab[255 - log_tab[i]] : 0); 162 q = ((p >> 7) | (p << 1)) ^ ((p >> 6) | (p << 2)); 163 p ^= 0x63 ^ q ^ ((q >> 6) | (q << 2)); 164 sbx_tab[i] = p; 165 isb_tab[p] = (u8) i; 166 } 167 168 for (i = 0; i < 256; ++i) { 169 p = sbx_tab[i]; 170 171 t = p; 172 fl_tab[0][i] = t; 173 fl_tab[1][i] = rol32(t, 8); 174 fl_tab[2][i] = rol32(t, 16); 175 fl_tab[3][i] = rol32(t, 24); 176 177 t = ((u32) ff_mult (2, p)) | 178 ((u32) p << 8) | 179 ((u32) p << 16) | ((u32) ff_mult (3, p) << 24); 180 181 ft_tab[0][i] = t; 182 ft_tab[1][i] = rol32(t, 8); 183 ft_tab[2][i] = rol32(t, 16); 184 ft_tab[3][i] = rol32(t, 24); 185 186 p = isb_tab[i]; 187 188 t = p; 189 il_tab[0][i] = t; 190 il_tab[1][i] = rol32(t, 8); 191 il_tab[2][i] = rol32(t, 16); 192 il_tab[3][i] = rol32(t, 24); 193 194 t = ((u32) ff_mult (14, p)) | 195 ((u32) ff_mult (9, p) << 8) | 196 ((u32) ff_mult (13, p) << 16) | 197 ((u32) ff_mult (11, p) << 24); 198 199 it_tab[0][i] = t; 200 it_tab[1][i] = rol32(t, 8); 201 it_tab[2][i] = rol32(t, 16); 202 it_tab[3][i] = rol32(t, 24); 203 } 204 } 205 206 #define star_x(x) (((x) & 0x7f7f7f7f) << 1) ^ ((((x) & 0x80808080) >> 7) * 0x1b) 207 208 #define imix_col(y,x) \ 209 u = star_x(x); \ 210 v = star_x(u); \ 211 w = star_x(v); \ 212 t = w ^ (x); \ 213 (y) = u ^ v ^ w; \ 214 (y) ^= ror32(u ^ t, 8) ^ \ 215 ror32(v ^ t, 16) ^ \ 216 ror32(t,24) 217 218 /* initialise the key schedule from the user supplied key */ 219 220 #define loop4(i) \ 221 { t = ror32(t, 8); t = ls_box(t) ^ rco_tab[i]; \ 222 t ^= E_KEY[4 * i]; E_KEY[4 * i + 4] = t; \ 223 t ^= E_KEY[4 * i + 1]; E_KEY[4 * i + 5] = t; \ 224 t ^= E_KEY[4 * i + 2]; E_KEY[4 * i + 6] = t; \ 225 t ^= E_KEY[4 * i + 3]; E_KEY[4 * i + 7] = t; \ 226 } 227 228 #define loop6(i) \ 229 { t = ror32(t, 8); t = ls_box(t) ^ rco_tab[i]; \ 230 t ^= E_KEY[6 * i]; E_KEY[6 * i + 6] = t; \ 231 t ^= E_KEY[6 * i + 1]; E_KEY[6 * i + 7] = t; \ 232 t ^= E_KEY[6 * i + 2]; E_KEY[6 * i + 8] = t; \ 233 t ^= E_KEY[6 * i + 3]; E_KEY[6 * i + 9] = t; \ 234 t ^= E_KEY[6 * i + 4]; E_KEY[6 * i + 10] = t; \ 235 t ^= E_KEY[6 * i + 5]; E_KEY[6 * i + 11] = t; \ 236 } 237 238 #define loop8(i) \ 239 { t = ror32(t, 8); ; t = ls_box(t) ^ rco_tab[i]; \ 240 t ^= E_KEY[8 * i]; E_KEY[8 * i + 8] = t; \ 241 t ^= E_KEY[8 * i + 1]; E_KEY[8 * i + 9] = t; \ 242 t ^= E_KEY[8 * i + 2]; E_KEY[8 * i + 10] = t; \ 243 t ^= E_KEY[8 * i + 3]; E_KEY[8 * i + 11] = t; \ 244 t = E_KEY[8 * i + 4] ^ ls_box(t); \ 245 E_KEY[8 * i + 12] = t; \ 246 t ^= E_KEY[8 * i + 5]; E_KEY[8 * i + 13] = t; \ 247 t ^= E_KEY[8 * i + 6]; E_KEY[8 * i + 14] = t; \ 248 t ^= E_KEY[8 * i + 7]; E_KEY[8 * i + 15] = t; \ 249 } 250 251 static int aes_set_key(struct crypto_tfm *tfm, const u8 *in_key, 252 unsigned int key_len) 253 { 254 struct aes_ctx *ctx = crypto_tfm_ctx(tfm); 255 const __le32 *key = (const __le32 *)in_key; 256 u32 *flags = &tfm->crt_flags; 257 u32 i, t, u, v, w; 258 259 if (key_len % 8) { 260 *flags |= CRYPTO_TFM_RES_BAD_KEY_LEN; 261 return -EINVAL; 262 } 263 264 ctx->key_length = key_len; 265 266 E_KEY[0] = le32_to_cpu(key[0]); 267 E_KEY[1] = le32_to_cpu(key[1]); 268 E_KEY[2] = le32_to_cpu(key[2]); 269 E_KEY[3] = le32_to_cpu(key[3]); 270 271 switch (key_len) { 272 case 16: 273 t = E_KEY[3]; 274 for (i = 0; i < 10; ++i) 275 loop4 (i); 276 break; 277 278 case 24: 279 E_KEY[4] = le32_to_cpu(key[4]); 280 t = E_KEY[5] = le32_to_cpu(key[5]); 281 for (i = 0; i < 8; ++i) 282 loop6 (i); 283 break; 284 285 case 32: 286 E_KEY[4] = le32_to_cpu(key[4]); 287 E_KEY[5] = le32_to_cpu(key[5]); 288 E_KEY[6] = le32_to_cpu(key[6]); 289 t = E_KEY[7] = le32_to_cpu(key[7]); 290 for (i = 0; i < 7; ++i) 291 loop8 (i); 292 break; 293 } 294 295 D_KEY[0] = E_KEY[0]; 296 D_KEY[1] = E_KEY[1]; 297 D_KEY[2] = E_KEY[2]; 298 D_KEY[3] = E_KEY[3]; 299 300 for (i = 4; i < key_len + 24; ++i) { 301 imix_col (D_KEY[i], E_KEY[i]); 302 } 303 304 return 0; 305 } 306 307 /* encrypt a block of text */ 308 309 #define f_nround(bo, bi, k) \ 310 f_rn(bo, bi, 0, k); \ 311 f_rn(bo, bi, 1, k); \ 312 f_rn(bo, bi, 2, k); \ 313 f_rn(bo, bi, 3, k); \ 314 k += 4 315 316 #define f_lround(bo, bi, k) \ 317 f_rl(bo, bi, 0, k); \ 318 f_rl(bo, bi, 1, k); \ 319 f_rl(bo, bi, 2, k); \ 320 f_rl(bo, bi, 3, k) 321 322 static void aes_encrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in) 323 { 324 const struct aes_ctx *ctx = crypto_tfm_ctx(tfm); 325 const __le32 *src = (const __le32 *)in; 326 __le32 *dst = (__le32 *)out; 327 u32 b0[4], b1[4]; 328 const u32 *kp = E_KEY + 4; 329 330 b0[0] = le32_to_cpu(src[0]) ^ E_KEY[0]; 331 b0[1] = le32_to_cpu(src[1]) ^ E_KEY[1]; 332 b0[2] = le32_to_cpu(src[2]) ^ E_KEY[2]; 333 b0[3] = le32_to_cpu(src[3]) ^ E_KEY[3]; 334 335 if (ctx->key_length > 24) { 336 f_nround (b1, b0, kp); 337 f_nround (b0, b1, kp); 338 } 339 340 if (ctx->key_length > 16) { 341 f_nround (b1, b0, kp); 342 f_nround (b0, b1, kp); 343 } 344 345 f_nround (b1, b0, kp); 346 f_nround (b0, b1, kp); 347 f_nround (b1, b0, kp); 348 f_nround (b0, b1, kp); 349 f_nround (b1, b0, kp); 350 f_nround (b0, b1, kp); 351 f_nround (b1, b0, kp); 352 f_nround (b0, b1, kp); 353 f_nround (b1, b0, kp); 354 f_lround (b0, b1, kp); 355 356 dst[0] = cpu_to_le32(b0[0]); 357 dst[1] = cpu_to_le32(b0[1]); 358 dst[2] = cpu_to_le32(b0[2]); 359 dst[3] = cpu_to_le32(b0[3]); 360 } 361 362 /* decrypt a block of text */ 363 364 #define i_nround(bo, bi, k) \ 365 i_rn(bo, bi, 0, k); \ 366 i_rn(bo, bi, 1, k); \ 367 i_rn(bo, bi, 2, k); \ 368 i_rn(bo, bi, 3, k); \ 369 k -= 4 370 371 #define i_lround(bo, bi, k) \ 372 i_rl(bo, bi, 0, k); \ 373 i_rl(bo, bi, 1, k); \ 374 i_rl(bo, bi, 2, k); \ 375 i_rl(bo, bi, 3, k) 376 377 static void aes_decrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in) 378 { 379 const struct aes_ctx *ctx = crypto_tfm_ctx(tfm); 380 const __le32 *src = (const __le32 *)in; 381 __le32 *dst = (__le32 *)out; 382 u32 b0[4], b1[4]; 383 const int key_len = ctx->key_length; 384 const u32 *kp = D_KEY + key_len + 20; 385 386 b0[0] = le32_to_cpu(src[0]) ^ E_KEY[key_len + 24]; 387 b0[1] = le32_to_cpu(src[1]) ^ E_KEY[key_len + 25]; 388 b0[2] = le32_to_cpu(src[2]) ^ E_KEY[key_len + 26]; 389 b0[3] = le32_to_cpu(src[3]) ^ E_KEY[key_len + 27]; 390 391 if (key_len > 24) { 392 i_nround (b1, b0, kp); 393 i_nround (b0, b1, kp); 394 } 395 396 if (key_len > 16) { 397 i_nround (b1, b0, kp); 398 i_nround (b0, b1, kp); 399 } 400 401 i_nround (b1, b0, kp); 402 i_nround (b0, b1, kp); 403 i_nround (b1, b0, kp); 404 i_nround (b0, b1, kp); 405 i_nround (b1, b0, kp); 406 i_nround (b0, b1, kp); 407 i_nround (b1, b0, kp); 408 i_nround (b0, b1, kp); 409 i_nround (b1, b0, kp); 410 i_lround (b0, b1, kp); 411 412 dst[0] = cpu_to_le32(b0[0]); 413 dst[1] = cpu_to_le32(b0[1]); 414 dst[2] = cpu_to_le32(b0[2]); 415 dst[3] = cpu_to_le32(b0[3]); 416 } 417 418 419 static struct crypto_alg aes_alg = { 420 .cra_name = "aes", 421 .cra_driver_name = "aes-generic", 422 .cra_priority = 100, 423 .cra_flags = CRYPTO_ALG_TYPE_CIPHER, 424 .cra_blocksize = AES_BLOCK_SIZE, 425 .cra_ctxsize = sizeof(struct aes_ctx), 426 .cra_alignmask = 3, 427 .cra_module = THIS_MODULE, 428 .cra_list = LIST_HEAD_INIT(aes_alg.cra_list), 429 .cra_u = { 430 .cipher = { 431 .cia_min_keysize = AES_MIN_KEY_SIZE, 432 .cia_max_keysize = AES_MAX_KEY_SIZE, 433 .cia_setkey = aes_set_key, 434 .cia_encrypt = aes_encrypt, 435 .cia_decrypt = aes_decrypt 436 } 437 } 438 }; 439 440 static int __init aes_init(void) 441 { 442 gen_tabs(); 443 return crypto_register_alg(&aes_alg); 444 } 445 446 static void __exit aes_fini(void) 447 { 448 crypto_unregister_alg(&aes_alg); 449 } 450 451 module_init(aes_init); 452 module_exit(aes_fini); 453 454 MODULE_DESCRIPTION("Rijndael (AES) Cipher Algorithm"); 455 MODULE_LICENSE("Dual BSD/GPL"); 456
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