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aes_generic.c
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aes_generic.c
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/*
* Cryptographic API.
*
* AES Cipher Algorithm.
*
* Based on Brian Gladman's code.
*
* Linux developers:
* Alexander Kjeldaas <[email protected]>
* Herbert Valerio Riedel <[email protected]>
* Kyle McMartin <[email protected]>
* Adam J. Richter <[email protected]> (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 <[email protected]>, 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");