linux/crypto/aes.c
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   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 */
  70static inline u8
  71byte(const u32 x, const unsigned n)
  72{
  73        return x >> (n << 3);
  74}
  75
  76struct 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
  84static u8 pow_tab[256] __initdata;
  85static u8 log_tab[256] __initdata;
  86static u8 sbx_tab[256] __initdata;
  87static u8 isb_tab[256] __initdata;
  88static u32 rco_tab[10];
  89static u32 ft_tab[4][256];
  90static u32 it_tab[4][256];
  91
  92static u32 fl_tab[4][256];
  93static u32 il_tab[4][256];
  94
  95static inline u8 __init
  96f_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
 135static void __init
 136gen_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
 251static 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
 322static 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
 377static 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
 419static 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
 440static int __init aes_init(void)
 441{
 442        gen_tabs();
 443        return crypto_register_alg(&aes_alg);
 444}
 445
 446static void __exit aes_fini(void)
 447{
 448        crypto_unregister_alg(&aes_alg);
 449}
 450
 451module_init(aes_init);
 452module_exit(aes_fini);
 453
 454MODULE_DESCRIPTION("Rijndael (AES) Cipher Algorithm");
 455MODULE_LICENSE("Dual BSD/GPL");
 456
 457