arch/x86_64/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  *  Andreas Steinmetz <ast@domdv.de> (adapted to x86_64 assembler)
  14  *
  15  * This program is free software; you can redistribute it and/or modify
  16  * it under the terms of the GNU General Public License as published by
  17  * the Free Software Foundation; either version 2 of the License, or
  18  * (at your option) any later version.
  19  *
  20  * ---------------------------------------------------------------------------
  21  * Copyright (c) 2002, Dr Brian Gladman <brg@gladman.me.uk>, Worcester, UK.
  22  * All rights reserved.
  23  *
  24  * LICENSE TERMS
  25  *
  26  * The free distribution and use of this software in both source and binary
  27  * form is allowed (with or without changes) provided that:
  28  *
  29  *   1. distributions of this source code include the above copyright
  30  *      notice, this list of conditions and the following disclaimer;
  31  *
  32  *   2. distributions in binary form include the above copyright
  33  *      notice, this list of conditions and the following disclaimer
  34  *      in the documentation and/or other associated materials;
  35  *
  36  *   3. the copyright holder's name is not used to endorse products
  37  *      built using this software without specific written permission.
  38  *
  39  * ALTERNATIVELY, provided that this notice is retained in full, this product
  40  * may be distributed under the terms of the GNU General Public License (GPL),
  41  * in which case the provisions of the GPL apply INSTEAD OF those given above.
  42  *
  43  * DISCLAIMER
  44  *
  45  * This software is provided 'as is' with no explicit or implied warranties
  46  * in respect of its properties, including, but not limited to, correctness
  47  * and/or fitness for purpose.
  48  * ---------------------------------------------------------------------------
  49  */
  50
  51 /* Some changes from the Gladman version:
  52     s/RIJNDAEL(e_key)/E_KEY/g
  53     s/RIJNDAEL(d_key)/D_KEY/g
  54 */
  55
  56 #include <asm/byteorder.h>
  57 #include <linux/bitops.h>
  58 #include <linux/crypto.h>
  59 #include <linux/errno.h>
  60 #include <linux/init.h>
  61 #include <linux/module.h>
  62 #include <linux/types.h>
  63
  64 #define AES_MIN_KEY_SIZE        16
  65 #define AES_MAX_KEY_SIZE        32
  66
  67 #define AES_BLOCK_SIZE          16
  68
  69 /*
  70  * #define byte(x, nr) ((unsigned char)((x) >> (nr*8)))
  71  */
  72 static inline u8 byte(const u32 x, const unsigned n)
  73 {
  74         return x >> (n << 3);
  75 }
  76
  77 #define u32_in(x) le32_to_cpu(*(const __le32 *)(x))
  78
  79 struct aes_ctx
  80 {
  81         u32 key_length;
  82         u32 E[60];
  83         u32 D[60];
  84 };
  85
  86 #define E_KEY ctx->E
  87 #define D_KEY ctx->D
  88
  89 static u8 pow_tab[256] __initdata;
  90 static u8 log_tab[256] __initdata;
  91 static u8 sbx_tab[256] __initdata;
  92 static u8 isb_tab[256] __initdata;
  93 static u32 rco_tab[10];
  94 u32 aes_ft_tab[4][256];
  95 u32 aes_it_tab[4][256];
  96
  97 u32 aes_fl_tab[4][256];
  98 u32 aes_il_tab[4][256];
  99
 100 static inline u8 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 ls_box(x)                               \
 110         (aes_fl_tab[0][byte(x, 0)] ^            \
 111          aes_fl_tab[1][byte(x, 1)] ^            \
 112          aes_fl_tab[2][byte(x, 2)] ^            \
 113          aes_fl_tab[3][byte(x, 3)])
 114
 115 static void __init gen_tabs(void)
 116 {
 117         u32 i, t;
 118         u8 p, q;
 119
 120         /* log and power tables for GF(2**8) finite field with
 121            0x011b as modular polynomial - the simplest primitive
 122            root is 0x03, used here to generate the tables */
 123
 124         for (i = 0, p = 1; i < 256; ++i) {
 125                 pow_tab[i] = (u8)p;
 126                 log_tab[p] = (u8)i;
 127
 128                 p ^= (p << 1) ^ (p & 0x80 ? 0x01b : 0);
 129         }
 130
 131         log_tab[1] = 0;
 132
 133         for (i = 0, p = 1; i < 10; ++i) {
 134                 rco_tab[i] = p;
 135
 136                 p = (p << 1) ^ (p & 0x80 ? 0x01b : 0);
 137         }
 138
 139         for (i = 0; i < 256; ++i) {
 140                 p = (i ? pow_tab[255 - log_tab[i]] : 0);
 141                 q = ((p >> 7) | (p << 1)) ^ ((p >> 6) | (p << 2));
 142                 p ^= 0x63 ^ q ^ ((q >> 6) | (q << 2));
 143                 sbx_tab[i] = p;
 144                 isb_tab[p] = (u8)i;
 145         }
 146
 147         for (i = 0; i < 256; ++i) {
 148                 p = sbx_tab[i];
 149
 150                 t = p;
 151                 aes_fl_tab[0][i] = t;
 152                 aes_fl_tab[1][i] = rol32(t, 8);
 153                 aes_fl_tab[2][i] = rol32(t, 16);
 154                 aes_fl_tab[3][i] = rol32(t, 24);
 155
 156                 t = ((u32)ff_mult(2, p)) |
 157                     ((u32)p << 8) |
 158                     ((u32)p << 16) | ((u32)ff_mult(3, p) << 24);
 159
 160                 aes_ft_tab[0][i] = t;
 161                 aes_ft_tab[1][i] = rol32(t, 8);
 162                 aes_ft_tab[2][i] = rol32(t, 16);
 163                 aes_ft_tab[3][i] = rol32(t, 24);
 164
 165                 p = isb_tab[i];
 166
 167                 t = p;
 168                 aes_il_tab[0][i] = t;
 169                 aes_il_tab[1][i] = rol32(t, 8);
 170                 aes_il_tab[2][i] = rol32(t, 16);
 171                 aes_il_tab[3][i] = rol32(t, 24);
 172
 173                 t = ((u32)ff_mult(14, p)) |
 174                     ((u32)ff_mult(9, p) << 8) |
 175                     ((u32)ff_mult(13, p) << 16) |
 176                     ((u32)ff_mult(11, p) << 24);
 177
 178                 aes_it_tab[0][i] = t;
 179                 aes_it_tab[1][i] = rol32(t, 8);
 180                 aes_it_tab[2][i] = rol32(t, 16);
 181                 aes_it_tab[3][i] = rol32(t, 24);
 182         }
 183 }
 184
 185 #define star_x(x) (((x) & 0x7f7f7f7f) << 1) ^ ((((x) & 0x80808080) >> 7) * 0x1b)
 186
 187 #define imix_col(y, x)                  \
 188         u    = star_x(x);               \
 189         v    = star_x(u);               \
 190         w    = star_x(v);               \
 191         t    = w ^ (x);                 \
 192         (y)  = u ^ v ^ w;               \
 193         (y) ^= ror32(u ^ t,  8) ^       \
 194                ror32(v ^ t, 16) ^       \
 195                ror32(t, 24)
 196
 197 /* initialise the key schedule from the user supplied key */
 198
 199 #define loop4(i)                                        \
 200 {                                                       \
 201         t = ror32(t,  8); t = ls_box(t) ^ rco_tab[i];   \
 202         t ^= E_KEY[4 * i];     E_KEY[4 * i + 4] = t;    \
 203         t ^= E_KEY[4 * i + 1]; E_KEY[4 * i + 5] = t;    \
 204         t ^= E_KEY[4 * i + 2]; E_KEY[4 * i + 6] = t;    \
 205         t ^= E_KEY[4 * i + 3]; E_KEY[4 * i + 7] = t;    \
 206 }
 207
 208 #define loop6(i)                                        \
 209 {                                                       \
 210         t = ror32(t,  8); t = ls_box(t) ^ rco_tab[i];   \
 211         t ^= E_KEY[6 * i];     E_KEY[6 * i + 6] = t;    \
 212         t ^= E_KEY[6 * i + 1]; E_KEY[6 * i + 7] = t;    \
 213         t ^= E_KEY[6 * i + 2]; E_KEY[6 * i + 8] = t;    \
 214         t ^= E_KEY[6 * i + 3]; E_KEY[6 * i + 9] = t;    \
 215         t ^= E_KEY[6 * i + 4]; E_KEY[6 * i + 10] = t;   \
 216         t ^= E_KEY[6 * i + 5]; E_KEY[6 * i + 11] = t;   \
 217 }
 218
 219 #define loop8(i)                                        \
 220 {                                                       \
 221         t = ror32(t,  8); ; t = ls_box(t) ^ rco_tab[i]; \
 222         t ^= E_KEY[8 * i];     E_KEY[8 * i + 8] = t;    \
 223         t ^= E_KEY[8 * i + 1]; E_KEY[8 * i + 9] = t;    \
 224         t ^= E_KEY[8 * i + 2]; E_KEY[8 * i + 10] = t;   \
 225         t ^= E_KEY[8 * i + 3]; E_KEY[8 * i + 11] = t;   \
 226         t  = E_KEY[8 * i + 4] ^ ls_box(t);              \
 227         E_KEY[8 * i + 12] = t;                          \
 228         t ^= E_KEY[8 * i + 5]; E_KEY[8 * i + 13] = t;   \
 229         t ^= E_KEY[8 * i + 6]; E_KEY[8 * i + 14] = t;   \
 230         t ^= E_KEY[8 * i + 7]; E_KEY[8 * i + 15] = t;   \
 231 }
 232
 233 static int aes_set_key(void *ctx_arg, const u8 *in_key, unsigned int key_len,
 234                        u32 *flags)
 235 {
 236         struct aes_ctx *ctx = ctx_arg;
 237         u32 i, j, t, u, v, w;
 238
 239         if (key_len != 16 && key_len != 24 && key_len != 32) {
 240                 *flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
 241                 return -EINVAL;
 242         }
 243
 244         ctx->key_length = key_len;
 245
 246         D_KEY[key_len + 24] = E_KEY[0] = u32_in(in_key);
 247         D_KEY[key_len + 25] = E_KEY[1] = u32_in(in_key + 4);
 248         D_KEY[key_len + 26] = E_KEY[2] = u32_in(in_key + 8);
 249         D_KEY[key_len + 27] = E_KEY[3] = u32_in(in_key + 12);
 250
 251         switch (key_len) {
 252         case 16:
 253                 t = E_KEY[3];
 254                 for (i = 0; i < 10; ++i)
 255                         loop4(i);
 256                 break;
 257
 258         case 24:
 259                 E_KEY[4] = u32_in(in_key + 16);
 260                 t = E_KEY[5] = u32_in(in_key + 20);
 261                 for (i = 0; i < 8; ++i)
 262                         loop6 (i);
 263                 break;
 264
 265         case 32:
 266                 E_KEY[4] = u32_in(in_key + 16);
 267                 E_KEY[5] = u32_in(in_key + 20);
 268                 E_KEY[6] = u32_in(in_key + 24);
 269                 t = E_KEY[7] = u32_in(in_key + 28);
 270                 for (i = 0; i < 7; ++i)
 271                         loop8(i);
 272                 break;
 273         }
 274
 275         D_KEY[0] = E_KEY[key_len + 24];
 276         D_KEY[1] = E_KEY[key_len + 25];
 277         D_KEY[2] = E_KEY[key_len + 26];
 278         D_KEY[3] = E_KEY[key_len + 27];
 279
 280         for (i = 4; i < key_len + 24; ++i) {
 281                 j = key_len + 24 - (i & ~3) + (i & 3);
 282                 imix_col(D_KEY[j], E_KEY[i]);
 283         }
 284
 285         return 0;
 286 }
 287
 288 extern void aes_encrypt(void *ctx_arg, u8 *out, const u8 *in);
 289 extern void aes_decrypt(void *ctx_arg, u8 *out, const u8 *in);
 290
 291 static struct crypto_alg aes_alg = {
 292         .cra_name               =       "aes",
 293         .cra_flags              =       CRYPTO_ALG_TYPE_CIPHER,
 294         .cra_blocksize          =       AES_BLOCK_SIZE,
 295         .cra_ctxsize            =       sizeof(struct aes_ctx),
 296         .cra_module             =       THIS_MODULE,
 297         .cra_list               =       LIST_HEAD_INIT(aes_alg.cra_list),
 298         .cra_u                  =       {
 299                 .cipher = {
 300                         .cia_min_keysize        =       AES_MIN_KEY_SIZE,
 301                         .cia_max_keysize        =       AES_MAX_KEY_SIZE,
 302                         .cia_setkey             =       aes_set_key,
 303                         .cia_encrypt            =       aes_encrypt,
 304                         .cia_decrypt            =       aes_decrypt
 305                 }
 306         }
 307 };
 308
 309 static int __init aes_init(void)
 310 {
 311         gen_tabs();
 312         return crypto_register_alg(&aes_alg);
 313 }
 314
 315 static void __exit aes_fini(void)
 316 {
 317         crypto_unregister_alg(&aes_alg);
 318 }
 319
 320 module_init(aes_init);
 321 module_exit(aes_fini);
 322
 323 MODULE_DESCRIPTION("Rijndael (AES) Cipher Algorithm");
 324 MODULE_LICENSE("GPL");
 325 MODULE_ALIAS("aes");