crypto/aes.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 /* 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