crypto/aes_generic.c

   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");