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 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] __initdata;
 106 static u8 log_tab[256] __initdata;
 107 static u8 sbx_tab[256] __initdata;
 108 static u8 isb_tab[256] __initdata;
 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 __init
 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 __init
 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 primitive
 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_setkey             =       aes_set_key,
 446                         .cia_encrypt            =       aes_encrypt,
 447                         .cia_decrypt            =       aes_decrypt
 448                 }
 449         }
 450 };
 451
 452 static int __init aes_init(void)
 453 {
 454         gen_tabs();
 455         return crypto_register_alg(&aes_alg);
 456 }
 457
 458 static void __exit aes_fini(void)
 459 {
 460         crypto_unregister_alg(&aes_alg);
 461 }
 462
 463 module_init(aes_init);
 464 module_exit(aes_fini);
 465
 466 MODULE_DESCRIPTION("Rijndael (AES) Cipher Algorithm");
 467 MODULE_LICENSE("Dual BSD/GPL");
 468