aes_generic.c 13.5 KB
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508
/* 
 * Cryptographic API.
 *
 * AES Cipher Algorithm.
 *
 * Based on Brian Gladman's code.
 *
 * Linux developers:
 *  Alexander Kjeldaas <astor@fast.no>
 *  Herbert Valerio Riedel <hvr@hvrlab.org>
 *  Kyle McMartin <kyle@debian.org>
 *  Adam J. Richter <adam@yggdrasil.com> (conversion to 2.5 API).
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * ---------------------------------------------------------------------------
 * Copyright (c) 2002, Dr Brian Gladman <brg@gladman.me.uk>, Worcester, UK.
 * All rights reserved.
 *
 * LICENSE TERMS
 *
 * The free distribution and use of this software in both source and binary
 * form is allowed (with or without changes) provided that:
 *
 *   1. distributions of this source code include the above copyright
 *      notice, this list of conditions and the following disclaimer;
 *
 *   2. distributions in binary form include the above copyright
 *      notice, this list of conditions and the following disclaimer
 *      in the documentation and/or other associated materials;
 *
 *   3. the copyright holder's name is not used to endorse products
 *      built using this software without specific written permission.
 *
 * ALTERNATIVELY, provided that this notice is retained in full, this product
 * may be distributed under the terms of the GNU General Public License (GPL),
 * in which case the provisions of the GPL apply INSTEAD OF those given above.
 *
 * DISCLAIMER
 *
 * This software is provided 'as is' with no explicit or implied warranties
 * in respect of its properties, including, but not limited to, correctness
 * and/or fitness for purpose.
 * ---------------------------------------------------------------------------
 */

#include <crypto/aes.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/crypto.h>
#include <asm/byteorder.h>

static inline u8 byte(const u32 x, const unsigned n)
{
	return x >> (n << 3);
}

static u8 pow_tab[256] __initdata;
static u8 log_tab[256] __initdata;
static u8 sbx_tab[256] __initdata;
static u8 isb_tab[256] __initdata;
static u32 rco_tab[10];

u32 crypto_ft_tab[4][256];
u32 crypto_fl_tab[4][256];
u32 crypto_it_tab[4][256];
u32 crypto_il_tab[4][256];

EXPORT_SYMBOL_GPL(crypto_ft_tab);
EXPORT_SYMBOL_GPL(crypto_fl_tab);
EXPORT_SYMBOL_GPL(crypto_it_tab);
EXPORT_SYMBOL_GPL(crypto_il_tab);

static inline u8 __init f_mult(u8 a, u8 b)
{
	u8 aa = log_tab[a], cc = aa + log_tab[b];

	return pow_tab[cc + (cc < aa ? 1 : 0)];
}

#define ff_mult(a, b)	(a && b ? f_mult(a, b) : 0)

static void __init gen_tabs(void)
{
	u32 i, t;
	u8 p, q;

	/*
	 * log and power tables for GF(2**8) finite field with
	 * 0x011b as modular polynomial - the simplest primitive
	 * root is 0x03, used here to generate the tables
	 */

	for (i = 0, p = 1; i < 256; ++i) {
		pow_tab[i] = (u8) p;
		log_tab[p] = (u8) i;

		p ^= (p << 1) ^ (p & 0x80 ? 0x01b : 0);
	}

	log_tab[1] = 0;

	for (i = 0, p = 1; i < 10; ++i) {
		rco_tab[i] = p;

		p = (p << 1) ^ (p & 0x80 ? 0x01b : 0);
	}

	for (i = 0; i < 256; ++i) {
		p = (i ? pow_tab[255 - log_tab[i]] : 0);
		q = ((p >> 7) | (p << 1)) ^ ((p >> 6) | (p << 2));
		p ^= 0x63 ^ q ^ ((q >> 6) | (q << 2));
		sbx_tab[i] = p;
		isb_tab[p] = (u8) i;
	}

	for (i = 0; i < 256; ++i) {
		p = sbx_tab[i];

		t = p;
		crypto_fl_tab[0][i] = t;
		crypto_fl_tab[1][i] = rol32(t, 8);
		crypto_fl_tab[2][i] = rol32(t, 16);
		crypto_fl_tab[3][i] = rol32(t, 24);

		t = ((u32) ff_mult(2, p)) |
		    ((u32) p << 8) |
		    ((u32) p << 16) | ((u32) ff_mult(3, p) << 24);

		crypto_ft_tab[0][i] = t;
		crypto_ft_tab[1][i] = rol32(t, 8);
		crypto_ft_tab[2][i] = rol32(t, 16);
		crypto_ft_tab[3][i] = rol32(t, 24);

		p = isb_tab[i];

		t = p;
		crypto_il_tab[0][i] = t;
		crypto_il_tab[1][i] = rol32(t, 8);
		crypto_il_tab[2][i] = rol32(t, 16);
		crypto_il_tab[3][i] = rol32(t, 24);

		t = ((u32) ff_mult(14, p)) |
		    ((u32) ff_mult(9, p) << 8) |
		    ((u32) ff_mult(13, p) << 16) |
		    ((u32) ff_mult(11, p) << 24);

		crypto_it_tab[0][i] = t;
		crypto_it_tab[1][i] = rol32(t, 8);
		crypto_it_tab[2][i] = rol32(t, 16);
		crypto_it_tab[3][i] = rol32(t, 24);
	}
}

/* initialise the key schedule from the user supplied key */

#define star_x(x) (((x) & 0x7f7f7f7f) << 1) ^ ((((x) & 0x80808080) >> 7) * 0x1b)

#define imix_col(y,x)	do {		\
	u	= star_x(x);		\
	v	= star_x(u);		\
	w	= star_x(v);		\
	t	= w ^ (x);		\
	(y)	= u ^ v ^ w;		\
	(y)	^= ror32(u ^ t, 8) ^	\
		ror32(v ^ t, 16) ^	\
		ror32(t, 24);		\
} while (0)

#define ls_box(x)		\
	crypto_fl_tab[0][byte(x, 0)] ^	\
	crypto_fl_tab[1][byte(x, 1)] ^	\
	crypto_fl_tab[2][byte(x, 2)] ^	\
	crypto_fl_tab[3][byte(x, 3)]

#define loop4(i)	do {		\
	t = ror32(t, 8);		\
	t = ls_box(t) ^ rco_tab[i];	\
	t ^= ctx->key_enc[4 * i];		\
	ctx->key_enc[4 * i + 4] = t;		\
	t ^= ctx->key_enc[4 * i + 1];		\
	ctx->key_enc[4 * i + 5] = t;		\
	t ^= ctx->key_enc[4 * i + 2];		\
	ctx->key_enc[4 * i + 6] = t;		\
	t ^= ctx->key_enc[4 * i + 3];		\
	ctx->key_enc[4 * i + 7] = t;		\
} while (0)

#define loop6(i)	do {		\
	t = ror32(t, 8);		\
	t = ls_box(t) ^ rco_tab[i];	\
	t ^= ctx->key_enc[6 * i];		\
	ctx->key_enc[6 * i + 6] = t;		\
	t ^= ctx->key_enc[6 * i + 1];		\
	ctx->key_enc[6 * i + 7] = t;		\
	t ^= ctx->key_enc[6 * i + 2];		\
	ctx->key_enc[6 * i + 8] = t;		\
	t ^= ctx->key_enc[6 * i + 3];		\
	ctx->key_enc[6 * i + 9] = t;		\
	t ^= ctx->key_enc[6 * i + 4];		\
	ctx->key_enc[6 * i + 10] = t;		\
	t ^= ctx->key_enc[6 * i + 5];		\
	ctx->key_enc[6 * i + 11] = t;		\
} while (0)

#define loop8(i)	do {			\
	t = ror32(t, 8);			\
	t = ls_box(t) ^ rco_tab[i];		\
	t ^= ctx->key_enc[8 * i];			\
	ctx->key_enc[8 * i + 8] = t;			\
	t ^= ctx->key_enc[8 * i + 1];			\
	ctx->key_enc[8 * i + 9] = t;			\
	t ^= ctx->key_enc[8 * i + 2];			\
	ctx->key_enc[8 * i + 10] = t;			\
	t ^= ctx->key_enc[8 * i + 3];			\
	ctx->key_enc[8 * i + 11] = t;			\
	t  = ctx->key_enc[8 * i + 4] ^ ls_box(t);	\
	ctx->key_enc[8 * i + 12] = t;			\
	t ^= ctx->key_enc[8 * i + 5];			\
	ctx->key_enc[8 * i + 13] = t;			\
	t ^= ctx->key_enc[8 * i + 6];			\
	ctx->key_enc[8 * i + 14] = t;			\
	t ^= ctx->key_enc[8 * i + 7];			\
	ctx->key_enc[8 * i + 15] = t;			\
} while (0)

/**
 * crypto_aes_expand_key - Expands the AES key as described in FIPS-197
 * @ctx:	The location where the computed key will be stored.
 * @in_key:	The supplied key.
 * @key_len:	The length of the supplied key.
 *
 * Returns 0 on success. The function fails only if an invalid key size (or
 * pointer) is supplied.
 * The expanded key size is 240 bytes (max of 14 rounds with a unique 16 bytes
 * key schedule plus a 16 bytes key which is used before the first round).
 * The decryption key is prepared for the "Equivalent Inverse Cipher" as
 * described in FIPS-197. The first slot (16 bytes) of each key (enc or dec) is
 * for the initial combination, the second slot for the first round and so on.
 */
int crypto_aes_expand_key(struct crypto_aes_ctx *ctx, const u8 *in_key,
		unsigned int key_len)
{
	const __le32 *key = (const __le32 *)in_key;
	u32 i, t, u, v, w, j;

	if (key_len != AES_KEYSIZE_128 && key_len != AES_KEYSIZE_192 &&
			key_len != AES_KEYSIZE_256)
		return -EINVAL;

	ctx->key_length = key_len;

	ctx->key_dec[key_len + 24] = ctx->key_enc[0] = le32_to_cpu(key[0]);
	ctx->key_dec[key_len + 25] = ctx->key_enc[1] = le32_to_cpu(key[1]);
	ctx->key_dec[key_len + 26] = ctx->key_enc[2] = le32_to_cpu(key[2]);
	ctx->key_dec[key_len + 27] = ctx->key_enc[3] = le32_to_cpu(key[3]);

	switch (key_len) {
	case AES_KEYSIZE_128:
		t = ctx->key_enc[3];
		for (i = 0; i < 10; ++i)
			loop4(i);
		break;

	case AES_KEYSIZE_192:
		ctx->key_enc[4] = le32_to_cpu(key[4]);
		t = ctx->key_enc[5] = le32_to_cpu(key[5]);
		for (i = 0; i < 8; ++i)
			loop6(i);
		break;

	case AES_KEYSIZE_256:
		ctx->key_enc[4] = le32_to_cpu(key[4]);
		ctx->key_enc[5] = le32_to_cpu(key[5]);
		ctx->key_enc[6] = le32_to_cpu(key[6]);
		t = ctx->key_enc[7] = le32_to_cpu(key[7]);
		for (i = 0; i < 7; ++i)
			loop8(i);
		break;
	}

	ctx->key_dec[0] = ctx->key_enc[key_len + 24];
	ctx->key_dec[1] = ctx->key_enc[key_len + 25];
	ctx->key_dec[2] = ctx->key_enc[key_len + 26];
	ctx->key_dec[3] = ctx->key_enc[key_len + 27];

	for (i = 4; i < key_len + 24; ++i) {
		j = key_len + 24 - (i & ~3) + (i & 3);
		imix_col(ctx->key_dec[j], ctx->key_enc[i]);
	}
	return 0;
}
EXPORT_SYMBOL_GPL(crypto_aes_expand_key);

/**
 * crypto_aes_set_key - Set the AES key.
 * @tfm:	The %crypto_tfm that is used in the context.
 * @in_key:	The input key.
 * @key_len:	The size of the key.
 *
 * Returns 0 on success, on failure the %CRYPTO_TFM_RES_BAD_KEY_LEN flag in tfm
 * is set. The function uses crypto_aes_expand_key() to expand the key.
 * &crypto_aes_ctx _must_ be the private data embedded in @tfm which is
 * retrieved with crypto_tfm_ctx().
 */
int crypto_aes_set_key(struct crypto_tfm *tfm, const u8 *in_key,
		unsigned int key_len)
{
	struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
	u32 *flags = &tfm->crt_flags;
	int ret;

	ret = crypto_aes_expand_key(ctx, in_key, key_len);
	if (!ret)
		return 0;

	*flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
	return -EINVAL;
}
EXPORT_SYMBOL_GPL(crypto_aes_set_key);

/* encrypt a block of text */

#define f_rn(bo, bi, n, k)	do {				\
	bo[n] = crypto_ft_tab[0][byte(bi[n], 0)] ^			\
		crypto_ft_tab[1][byte(bi[(n + 1) & 3], 1)] ^		\
		crypto_ft_tab[2][byte(bi[(n + 2) & 3], 2)] ^		\
		crypto_ft_tab[3][byte(bi[(n + 3) & 3], 3)] ^ *(k + n);	\
} while (0)

#define f_nround(bo, bi, k)	do {\
	f_rn(bo, bi, 0, k);	\
	f_rn(bo, bi, 1, k);	\
	f_rn(bo, bi, 2, k);	\
	f_rn(bo, bi, 3, k);	\
	k += 4;			\
} while (0)

#define f_rl(bo, bi, n, k)	do {				\
	bo[n] = crypto_fl_tab[0][byte(bi[n], 0)] ^			\
		crypto_fl_tab[1][byte(bi[(n + 1) & 3], 1)] ^		\
		crypto_fl_tab[2][byte(bi[(n + 2) & 3], 2)] ^		\
		crypto_fl_tab[3][byte(bi[(n + 3) & 3], 3)] ^ *(k + n);	\
} while (0)

#define f_lround(bo, bi, k)	do {\
	f_rl(bo, bi, 0, k);	\
	f_rl(bo, bi, 1, k);	\
	f_rl(bo, bi, 2, k);	\
	f_rl(bo, bi, 3, k);	\
} while (0)

static void aes_encrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
{
	const struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
	const __le32 *src = (const __le32 *)in;
	__le32 *dst = (__le32 *)out;
	u32 b0[4], b1[4];
	const u32 *kp = ctx->key_enc + 4;
	const int key_len = ctx->key_length;

	b0[0] = le32_to_cpu(src[0]) ^ ctx->key_enc[0];
	b0[1] = le32_to_cpu(src[1]) ^ ctx->key_enc[1];
	b0[2] = le32_to_cpu(src[2]) ^ ctx->key_enc[2];
	b0[3] = le32_to_cpu(src[3]) ^ ctx->key_enc[3];

	if (key_len > 24) {
		f_nround(b1, b0, kp);
		f_nround(b0, b1, kp);
	}

	if (key_len > 16) {
		f_nround(b1, b0, kp);
		f_nround(b0, b1, kp);
	}

	f_nround(b1, b0, kp);
	f_nround(b0, b1, kp);
	f_nround(b1, b0, kp);
	f_nround(b0, b1, kp);
	f_nround(b1, b0, kp);
	f_nround(b0, b1, kp);
	f_nround(b1, b0, kp);
	f_nround(b0, b1, kp);
	f_nround(b1, b0, kp);
	f_lround(b0, b1, kp);

	dst[0] = cpu_to_le32(b0[0]);
	dst[1] = cpu_to_le32(b0[1]);
	dst[2] = cpu_to_le32(b0[2]);
	dst[3] = cpu_to_le32(b0[3]);
}

/* decrypt a block of text */

#define i_rn(bo, bi, n, k)	do {				\
	bo[n] = crypto_it_tab[0][byte(bi[n], 0)] ^			\
		crypto_it_tab[1][byte(bi[(n + 3) & 3], 1)] ^		\
		crypto_it_tab[2][byte(bi[(n + 2) & 3], 2)] ^		\
		crypto_it_tab[3][byte(bi[(n + 1) & 3], 3)] ^ *(k + n);	\
} while (0)

#define i_nround(bo, bi, k)	do {\
	i_rn(bo, bi, 0, k);	\
	i_rn(bo, bi, 1, k);	\
	i_rn(bo, bi, 2, k);	\
	i_rn(bo, bi, 3, k);	\
	k += 4;			\
} while (0)

#define i_rl(bo, bi, n, k)	do {			\
	bo[n] = crypto_il_tab[0][byte(bi[n], 0)] ^		\
	crypto_il_tab[1][byte(bi[(n + 3) & 3], 1)] ^		\
	crypto_il_tab[2][byte(bi[(n + 2) & 3], 2)] ^		\
	crypto_il_tab[3][byte(bi[(n + 1) & 3], 3)] ^ *(k + n);	\
} while (0)

#define i_lround(bo, bi, k)	do {\
	i_rl(bo, bi, 0, k);	\
	i_rl(bo, bi, 1, k);	\
	i_rl(bo, bi, 2, k);	\
	i_rl(bo, bi, 3, k);	\
} while (0)

static void aes_decrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
{
	const struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
	const __le32 *src = (const __le32 *)in;
	__le32 *dst = (__le32 *)out;
	u32 b0[4], b1[4];
	const int key_len = ctx->key_length;
	const u32 *kp = ctx->key_dec + 4;

	b0[0] = le32_to_cpu(src[0]) ^  ctx->key_dec[0];
	b0[1] = le32_to_cpu(src[1]) ^  ctx->key_dec[1];
	b0[2] = le32_to_cpu(src[2]) ^  ctx->key_dec[2];
	b0[3] = le32_to_cpu(src[3]) ^  ctx->key_dec[3];

	if (key_len > 24) {
		i_nround(b1, b0, kp);
		i_nround(b0, b1, kp);
	}

	if (key_len > 16) {
		i_nround(b1, b0, kp);
		i_nround(b0, b1, kp);
	}

	i_nround(b1, b0, kp);
	i_nround(b0, b1, kp);
	i_nround(b1, b0, kp);
	i_nround(b0, b1, kp);
	i_nround(b1, b0, kp);
	i_nround(b0, b1, kp);
	i_nround(b1, b0, kp);
	i_nround(b0, b1, kp);
	i_nround(b1, b0, kp);
	i_lround(b0, b1, kp);

	dst[0] = cpu_to_le32(b0[0]);
	dst[1] = cpu_to_le32(b0[1]);
	dst[2] = cpu_to_le32(b0[2]);
	dst[3] = cpu_to_le32(b0[3]);
}

static struct crypto_alg aes_alg = {
	.cra_name		=	"aes",
	.cra_driver_name	=	"aes-generic",
	.cra_priority		=	100,
	.cra_flags		=	CRYPTO_ALG_TYPE_CIPHER,
	.cra_blocksize		=	AES_BLOCK_SIZE,
	.cra_ctxsize		=	sizeof(struct crypto_aes_ctx),
	.cra_alignmask		=	3,
	.cra_module		=	THIS_MODULE,
	.cra_list		=	LIST_HEAD_INIT(aes_alg.cra_list),
	.cra_u			=	{
		.cipher = {
			.cia_min_keysize	=	AES_MIN_KEY_SIZE,
			.cia_max_keysize	=	AES_MAX_KEY_SIZE,
			.cia_setkey		=	crypto_aes_set_key,
			.cia_encrypt		=	aes_encrypt,
			.cia_decrypt		=	aes_decrypt
		}
	}
};

static int __init aes_init(void)
{
	gen_tabs();
	return crypto_register_alg(&aes_alg);
}

static void __exit aes_fini(void)
{
	crypto_unregister_alg(&aes_alg);
}

module_init(aes_init);
module_exit(aes_fini);

MODULE_DESCRIPTION("Rijndael (AES) Cipher Algorithm");
MODULE_LICENSE("Dual BSD/GPL");
MODULE_ALIAS("aes");