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 inline static u8
  71 byte(const u32 x, const unsigned n)
  72 {
  73         return x >> (n << 3);
  74 }
  75
  76 #define u32_in(x) le32_to_cpu(*(const u32 *)(x))
  77 #define u32_out(to, from) (*(u32 *)(to) = cpu_to_le32(from))
  78
  79 struct aes_ctx {
  80         int key_length;
  81         u32 E[60];
  82         u32 D[60];
  83 };
  84
  85 #define E_KEY ctx->E
  86 #define D_KEY ctx->D
  87
  88 static u8 pow_tab[256] __initdata;
  89 static u8 log_tab[256] __initdata;
  90 static u8 sbx_tab[256] __initdata;
  91 static u8 isb_tab[256] __initdata;
  92 static u32 rco_tab[10];
  93 static u32 ft_tab[4][256];
  94 static u32 it_tab[4][256];
  95
  96 static u32 fl_tab[4][256];
  97 static u32 il_tab[4][256];
  98
  99 static inline u8 __init
 100 f_mult (u8 a, u8 b)
 101 {
 102         u8 aa = log_tab[a], cc = aa + log_tab[b];
 103
 104         return pow_tab[cc + (cc < aa ? 1 : 0)];
 105 }
 106
 107 #define ff_mult(a,b)    (a && b ? f_mult(a, b) : 0)
 108
 109 #define f_rn(bo, bi, n, k)                                      \
 110     bo[n] =  ft_tab[0][byte(bi[n],0)] ^                         \
 111              ft_tab[1][byte(bi[(n + 1) & 3],1)] ^               \
 112              ft_tab[2][byte(bi[(n + 2) & 3],2)] ^               \
 113              ft_tab[3][byte(bi[(n + 3) & 3],3)] ^ *(k + n)
 114
 115 #define i_rn(bo, bi, n, k)                                      \
 116     bo[n] =  it_tab[0][byte(bi[n],0)] ^                         \
 117              it_tab[1][byte(bi[(n + 3) & 3],1)] ^               \
 118              it_tab[2][byte(bi[(n + 2) & 3],2)] ^               \
 119              it_tab[3][byte(bi[(n + 1) & 3],3)] ^ *(k + n)
 120
 121 #define ls_box(x)                               \
 122     ( fl_tab[0][byte(x, 0)] ^                   \
 123       fl_tab[1][byte(x, 1)] ^                   \
 124       fl_tab[2][byte(x, 2)] ^                   \
 125       fl_tab[3][byte(x, 3)] )
 126
 127 #define f_rl(bo, bi, n, k)                                      \
 128     bo[n] =  fl_tab[0][byte(bi[n],0)] ^                         \
 129              fl_tab[1][byte(bi[(n + 1) & 3],1)] ^               \
 130              fl_tab[2][byte(bi[(n + 2) & 3],2)] ^               \
 131              fl_tab[3][byte(bi[(n + 3) & 3],3)] ^ *(k + n)
 132
 133 #define i_rl(bo, bi, n, k)                                      \
 134     bo[n] =  il_tab[0][byte(bi[n],0)] ^                         \
 135              il_tab[1][byte(bi[(n + 3) & 3],1)] ^               \
 136              il_tab[2][byte(bi[(n + 2) & 3],2)] ^               \
 137              il_tab[3][byte(bi[(n + 1) & 3],3)] ^ *(k + n)
 138
 139 static void __init
 140 gen_tabs (void)
 141 {
 142         u32 i, t;
 143         u8 p, q;
 144
 145         /* log and power tables for GF(2**8) finite field with
 146            0x011b as modular polynomial - the simplest primitive
 147            root is 0x03, used here to generate the tables */
 148
 149         for (i = 0, p = 1; i < 256; ++i) {
 150                 pow_tab[i] = (u8) p;
 151                 log_tab[p] = (u8) i;
 152
 153                 p ^= (p << 1) ^ (p & 0x80 ? 0x01b : 0);
 154         }
 155
 156         log_tab[1] = 0;
 157
 158         for (i = 0, p = 1; i < 10; ++i) {
 159                 rco_tab[i] = p;
 160
 161                 p = (p << 1) ^ (p & 0x80 ? 0x01b : 0);
 162         }
 163
 164         for (i = 0; i < 256; ++i) {
 165                 p = (i ? pow_tab[255 - log_tab[i]] : 0);
 166                 q = ((p >> 7) | (p << 1)) ^ ((p >> 6) | (p << 2));
 167                 p ^= 0x63 ^ q ^ ((q >> 6) | (q << 2));
 168                 sbx_tab[i] = p;
 169                 isb_tab[p] = (u8) i;
 170         }
 171
 172         for (i = 0; i < 256; ++i) {
 173                 p = sbx_tab[i];
 174
 175                 t = p;
 176                 fl_tab[0][i] = t;
 177                 fl_tab[1][i] = rol32(t, 8);
 178                 fl_tab[2][i] = rol32(t, 16);
 179                 fl_tab[3][i] = rol32(t, 24);
 180
 181                 t = ((u32) ff_mult (2, p)) |
 182                     ((u32) p << 8) |
 183                     ((u32) p << 16) | ((u32) ff_mult (3, p) << 24);
 184
 185                 ft_tab[0][i] = t;
 186                 ft_tab[1][i] = rol32(t, 8);
 187                 ft_tab[2][i] = rol32(t, 16);
 188                 ft_tab[3][i] = rol32(t, 24);
 189
 190                 p = isb_tab[i];
 191
 192                 t = p;
 193                 il_tab[0][i] = t;
 194                 il_tab[1][i] = rol32(t, 8);
 195                 il_tab[2][i] = rol32(t, 16);
 196                 il_tab[3][i] = rol32(t, 24);
 197
 198                 t = ((u32) ff_mult (14, p)) |
 199                     ((u32) ff_mult (9, p) << 8) |
 200                     ((u32) ff_mult (13, p) << 16) |
 201                     ((u32) ff_mult (11, p) << 24);
 202
 203                 it_tab[0][i] = t;
 204                 it_tab[1][i] = rol32(t, 8);
 205                 it_tab[2][i] = rol32(t, 16);
 206                 it_tab[3][i] = rol32(t, 24);
 207         }
 208 }
 209
 210 #define star_x(x) (((x) & 0x7f7f7f7f) << 1) ^ ((((x) & 0x80808080) >> 7) * 0x1b)
 211
 212 #define imix_col(y,x)       \
 213     u   = star_x(x);        \
 214     v   = star_x(u);        \
 215     w   = star_x(v);        \
 216     t   = w ^ (x);          \
 217    (y)  = u ^ v ^ w;        \
 218    (y) ^= ror32(u ^ t,  8) ^ \
 219           ror32(v ^ t, 16) ^ \
 220           ror32(t,24)
 221
 222 /* initialise the key schedule from the user supplied key */
 223
 224 #define loop4(i)                                    \
 225 {   t = ror32(t,  8); t = ls_box(t) ^ rco_tab[i];    \
 226     t ^= E_KEY[4 * i];     E_KEY[4 * i + 4] = t;    \
 227     t ^= E_KEY[4 * i + 1]; E_KEY[4 * i + 5] = t;    \
 228     t ^= E_KEY[4 * i + 2]; E_KEY[4 * i + 6] = t;    \
 229     t ^= E_KEY[4 * i + 3]; E_KEY[4 * i + 7] = t;    \
 230 }
 231
 232 #define loop6(i)                                    \
 233 {   t = ror32(t,  8); t = ls_box(t) ^ rco_tab[i];    \
 234     t ^= E_KEY[6 * i];     E_KEY[6 * i + 6] = t;    \
 235     t ^= E_KEY[6 * i + 1]; E_KEY[6 * i + 7] = t;    \
 236     t ^= E_KEY[6 * i + 2]; E_KEY[6 * i + 8] = t;    \
 237     t ^= E_KEY[6 * i + 3]; E_KEY[6 * i + 9] = t;    \
 238     t ^= E_KEY[6 * i + 4]; E_KEY[6 * i + 10] = t;   \
 239     t ^= E_KEY[6 * i + 5]; E_KEY[6 * i + 11] = t;   \
 240 }
 241
 242 #define loop8(i)                                    \
 243 {   t = ror32(t,  8); ; t = ls_box(t) ^ rco_tab[i];  \
 244     t ^= E_KEY[8 * i];     E_KEY[8 * i + 8] = t;    \
 245     t ^= E_KEY[8 * i + 1]; E_KEY[8 * i + 9] = t;    \
 246     t ^= E_KEY[8 * i + 2]; E_KEY[8 * i + 10] = t;   \
 247     t ^= E_KEY[8 * i + 3]; E_KEY[8 * i + 11] = t;   \
 248     t  = E_KEY[8 * i + 4] ^ ls_box(t);    \
 249     E_KEY[8 * i + 12] = t;                \
 250     t ^= E_KEY[8 * i + 5]; E_KEY[8 * i + 13] = t;   \
 251     t ^= E_KEY[8 * i + 6]; E_KEY[8 * i + 14] = t;   \
 252     t ^= E_KEY[8 * i + 7]; E_KEY[8 * i + 15] = t;   \
 253 }
 254
 255 static int
 256 aes_set_key(void *ctx_arg, const u8 *in_key, unsigned int key_len, u32 *flags)
 257 {
 258         struct aes_ctx *ctx = ctx_arg;
 259         u32 i, t, u, v, w;
 260
 261         if (key_len != 16 && key_len != 24 && key_len != 32) {
 262                 *flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
 263                 return -EINVAL;
 264         }
 265
 266         ctx->key_length = key_len;
 267
 268         E_KEY[0] = u32_in (in_key);
 269         E_KEY[1] = u32_in (in_key + 4);
 270         E_KEY[2] = u32_in (in_key + 8);
 271         E_KEY[3] = u32_in (in_key + 12);
 272
 273         switch (key_len) {
 274         case 16:
 275                 t = E_KEY[3];
 276                 for (i = 0; i < 10; ++i)
 277                         loop4 (i);
 278                 break;
 279
 280         case 24:
 281                 E_KEY[4] = u32_in (in_key + 16);
 282                 t = E_KEY[5] = u32_in (in_key + 20);
 283                 for (i = 0; i < 8; ++i)
 284                         loop6 (i);
 285                 break;
 286
 287         case 32:
 288                 E_KEY[4] = u32_in (in_key + 16);
 289                 E_KEY[5] = u32_in (in_key + 20);
 290                 E_KEY[6] = u32_in (in_key + 24);
 291                 t = E_KEY[7] = u32_in (in_key + 28);
 292                 for (i = 0; i < 7; ++i)
 293                         loop8 (i);
 294                 break;
 295         }
 296
 297         D_KEY[0] = E_KEY[0];
 298         D_KEY[1] = E_KEY[1];
 299         D_KEY[2] = E_KEY[2];
 300         D_KEY[3] = E_KEY[3];
 301
 302         for (i = 4; i < key_len + 24; ++i) {
 303                 imix_col (D_KEY[i], E_KEY[i]);
 304         }
 305
 306         return 0;
 307 }
 308
 309 /* encrypt a block of text */
 310
 311 #define f_nround(bo, bi, k) \
 312     f_rn(bo, bi, 0, k);     \
 313     f_rn(bo, bi, 1, k);     \
 314     f_rn(bo, bi, 2, k);     \
 315     f_rn(bo, bi, 3, k);     \
 316     k += 4
 317
 318 #define f_lround(bo, bi, k) \
 319     f_rl(bo, bi, 0, k);     \
 320     f_rl(bo, bi, 1, k);     \
 321     f_rl(bo, bi, 2, k);     \
 322     f_rl(bo, bi, 3, k)
 323
 324 static void aes_encrypt(void *ctx_arg, u8 *out, const u8 *in)
 325 {
 326         const struct aes_ctx *ctx = ctx_arg;
 327         u32 b0[4], b1[4];
 328         const u32 *kp = E_KEY + 4;
 329
 330         b0[0] = u32_in (in) ^ E_KEY[0];
 331         b0[1] = u32_in (in + 4) ^ E_KEY[1];
 332         b0[2] = u32_in (in + 8) ^ E_KEY[2];
 333         b0[3] = u32_in (in + 12) ^ 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         u32_out (out, b0[0]);
 357         u32_out (out + 4, b0[1]);
 358         u32_out (out + 8, b0[2]);
 359         u32_out (out + 12, 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(void *ctx_arg, u8 *out, const u8 *in)
 378 {
 379         const struct aes_ctx *ctx = ctx_arg;
 380         u32 b0[4], b1[4];
 381         const int key_len = ctx->key_length;
 382         const u32 *kp = D_KEY + key_len + 20;
 383
 384         b0[0] = u32_in (in) ^ E_KEY[key_len + 24];
 385         b0[1] = u32_in (in + 4) ^ E_KEY[key_len + 25];
 386         b0[2] = u32_in (in + 8) ^ E_KEY[key_len + 26];
 387         b0[3] = u32_in (in + 12) ^ E_KEY[key_len + 27];
 388
 389         if (key_len > 24) {
 390                 i_nround (b1, b0, kp);
 391                 i_nround (b0, b1, kp);
 392         }
 393
 394         if (key_len > 16) {
 395                 i_nround (b1, b0, kp);
 396                 i_nround (b0, b1, kp);
 397         }
 398
 399         i_nround (b1, b0, kp);
 400         i_nround (b0, b1, kp);
 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_lround (b0, b1, kp);
 409
 410         u32_out (out, b0[0]);
 411         u32_out (out + 4, b0[1]);
 412         u32_out (out + 8, b0[2]);
 413         u32_out (out + 12, b0[3]);
 414 }
 415
 416
 417 static struct crypto_alg aes_alg = {
 418         .cra_name               =       "aes",
 419         .cra_flags              =       CRYPTO_ALG_TYPE_CIPHER,
 420         .cra_blocksize          =       AES_BLOCK_SIZE,
 421         .cra_ctxsize            =       sizeof(struct aes_ctx),
 422         .cra_module             =       THIS_MODULE,
 423         .cra_list               =       LIST_HEAD_INIT(aes_alg.cra_list),
 424         .cra_u                  =       {
 425                 .cipher = {
 426                         .cia_min_keysize        =       AES_MIN_KEY_SIZE,
 427                         .cia_max_keysize        =       AES_MAX_KEY_SIZE,
 428                         .cia_setkey             =       aes_set_key,
 429                         .cia_encrypt            =       aes_encrypt,
 430                         .cia_decrypt            =       aes_decrypt
 431                 }
 432         }
 433 };
 434
 435 static int __init aes_init(void)
 436 {
 437         gen_tabs();
 438         return crypto_register_alg(&aes_alg);
 439 }
 440
 441 static void __exit aes_fini(void)
 442 {
 443         crypto_unregister_alg(&aes_alg);
 444 }
 445
 446 module_init(aes_init);
 447 module_exit(aes_fini);
 448
 449 MODULE_DESCRIPTION("Rijndael (AES) Cipher Algorithm");
 450 MODULE_LICENSE("Dual BSD/GPL");
 451