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 */
72static inline u8 byte(const u32 x, const unsigned n)
73{
74	return x >> (n << 3);
75}
76
77struct aes_ctx
78{
79	u32 key_length;
80	u32 buf[120];
81};
82
83#define E_KEY (&ctx->buf[0])
84#define D_KEY (&ctx->buf[60])
85
86static u8 pow_tab[256] __initdata;
87static u8 log_tab[256] __initdata;
88static u8 sbx_tab[256] __initdata;
89static u8 isb_tab[256] __initdata;
90static u32 rco_tab[10];
91u32 aes_ft_tab[4][256];
92u32 aes_it_tab[4][256];
93
94u32 aes_fl_tab[4][256];
95u32 aes_il_tab[4][256];
96
97static inline u8 f_mult(u8 a, u8 b)
98{
99	u8 aa = log_tab[a], cc = aa + log_tab[b];
100
101	return pow_tab[cc + (cc < aa ? 1 : 0)];
102}
103
104#define ff_mult(a, b) (a && b ? f_mult(a, b) : 0)
105
106#define ls_box(x)				\
107	(aes_fl_tab[0][byte(x, 0)] ^		\
108	 aes_fl_tab[1][byte(x, 1)] ^		\
109	 aes_fl_tab[2][byte(x, 2)] ^		\
110	 aes_fl_tab[3][byte(x, 3)])
111
112static void __init gen_tabs(void)
113{
114	u32 i, t;
115	u8 p, q;
116
117	/* log and power tables for GF(2**8) finite field with
118	   0x011b as modular polynomial - the simplest primitive
119	   root is 0x03, used here to generate the tables */
120
121	for (i = 0, p = 1; i < 256; ++i) {
122		pow_tab[i] = (u8)p;
123		log_tab[p] = (u8)i;
124
125		p ^= (p << 1) ^ (p & 0x80 ? 0x01b : 0);
126	}
127
128	log_tab[1] = 0;
129
130	for (i = 0, p = 1; i < 10; ++i) {
131		rco_tab[i] = p;
132
133		p = (p << 1) ^ (p & 0x80 ? 0x01b : 0);
134	}
135
136	for (i = 0; i < 256; ++i) {
137		p = (i ? pow_tab[255 - log_tab[i]] : 0);
138		q = ((p >> 7) | (p << 1)) ^ ((p >> 6) | (p << 2));
139		p ^= 0x63 ^ q ^ ((q >> 6) | (q << 2));
140		sbx_tab[i] = p;
141		isb_tab[p] = (u8)i;
142	}
143
144	for (i = 0; i < 256; ++i) {
145		p = sbx_tab[i];
146
147		t = p;
148		aes_fl_tab[0][i] = t;
149		aes_fl_tab[1][i] = rol32(t, 8);
150		aes_fl_tab[2][i] = rol32(t, 16);
151		aes_fl_tab[3][i] = rol32(t, 24);
152
153		t = ((u32)ff_mult(2, p)) |
154		    ((u32)p << 8) |
155		    ((u32)p << 16) | ((u32)ff_mult(3, p) << 24);
156
157		aes_ft_tab[0][i] = t;
158		aes_ft_tab[1][i] = rol32(t, 8);
159		aes_ft_tab[2][i] = rol32(t, 16);
160		aes_ft_tab[3][i] = rol32(t, 24);
161
162		p = isb_tab[i];
163
164		t = p;
165		aes_il_tab[0][i] = t;
166		aes_il_tab[1][i] = rol32(t, 8);
167		aes_il_tab[2][i] = rol32(t, 16);
168		aes_il_tab[3][i] = rol32(t, 24);
169
170		t = ((u32)ff_mult(14, p)) |
171		    ((u32)ff_mult(9, p) << 8) |
172		    ((u32)ff_mult(13, p) << 16) |
173		    ((u32)ff_mult(11, p) << 24);
174
175		aes_it_tab[0][i] = t;
176		aes_it_tab[1][i] = rol32(t, 8);
177		aes_it_tab[2][i] = rol32(t, 16);
178		aes_it_tab[3][i] = rol32(t, 24);
179	}
180}
181
182#define star_x(x) (((x) & 0x7f7f7f7f) << 1) ^ ((((x) & 0x80808080) >> 7) * 0x1b)
183
184#define imix_col(y, x)			\
185	u    = star_x(x);		\
186	v    = star_x(u);		\
187	w    = star_x(v);		\
188	t    = w ^ (x);			\
189	(y)  = u ^ v ^ w;		\
190	(y) ^= ror32(u ^ t,  8) ^	\
191	       ror32(v ^ t, 16) ^	\
192	       ror32(t, 24)
193
194/* initialise the key schedule from the user supplied key */
195
196#define loop4(i)					\
197{							\
198	t = ror32(t,  8); t = ls_box(t) ^ rco_tab[i];	\
199	t ^= E_KEY[4 * i];     E_KEY[4 * i + 4] = t;	\
200	t ^= E_KEY[4 * i + 1]; E_KEY[4 * i + 5] = t;	\
201	t ^= E_KEY[4 * i + 2]; E_KEY[4 * i + 6] = t;	\
202	t ^= E_KEY[4 * i + 3]; E_KEY[4 * i + 7] = t;	\
203}
204
205#define loop6(i)					\
206{							\
207	t = ror32(t,  8); t = ls_box(t) ^ rco_tab[i];	\
208	t ^= E_KEY[6 * i];     E_KEY[6 * i + 6] = t;	\
209	t ^= E_KEY[6 * i + 1]; E_KEY[6 * i + 7] = t;	\
210	t ^= E_KEY[6 * i + 2]; E_KEY[6 * i + 8] = t;	\
211	t ^= E_KEY[6 * i + 3]; E_KEY[6 * i + 9] = t;	\
212	t ^= E_KEY[6 * i + 4]; E_KEY[6 * i + 10] = t;	\
213	t ^= E_KEY[6 * i + 5]; E_KEY[6 * i + 11] = t;	\
214}
215
216#define loop8(i)					\
217{							\
218	t = ror32(t,  8); ; t = ls_box(t) ^ rco_tab[i];	\
219	t ^= E_KEY[8 * i];     E_KEY[8 * i + 8] = t;	\
220	t ^= E_KEY[8 * i + 1]; E_KEY[8 * i + 9] = t;	\
221	t ^= E_KEY[8 * i + 2]; E_KEY[8 * i + 10] = t;	\
222	t ^= E_KEY[8 * i + 3]; E_KEY[8 * i + 11] = t;	\
223	t  = E_KEY[8 * i + 4] ^ ls_box(t);		\
224	E_KEY[8 * i + 12] = t;				\
225	t ^= E_KEY[8 * i + 5]; E_KEY[8 * i + 13] = t;	\
226	t ^= E_KEY[8 * i + 6]; E_KEY[8 * i + 14] = t;	\
227	t ^= E_KEY[8 * i + 7]; E_KEY[8 * i + 15] = t;	\
228}
229
230static int aes_set_key(struct crypto_tfm *tfm, const u8 *in_key,
231		       unsigned int key_len)
232{
233	struct aes_ctx *ctx = crypto_tfm_ctx(tfm);
234	const __le32 *key = (const __le32 *)in_key;
235	u32 *flags = &tfm->crt_flags;
236	u32 i, j, t, u, v, w;
237
238	if (key_len % 8) {
239		*flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
240		return -EINVAL;
241	}
242
243	ctx->key_length = key_len;
244
245	D_KEY[key_len + 24] = E_KEY[0] = le32_to_cpu(key[0]);
246	D_KEY[key_len + 25] = E_KEY[1] = le32_to_cpu(key[1]);
247	D_KEY[key_len + 26] = E_KEY[2] = le32_to_cpu(key[2]);
248	D_KEY[key_len + 27] = E_KEY[3] = le32_to_cpu(key[3]);
249
250	switch (key_len) {
251	case 16:
252		t = E_KEY[3];
253		for (i = 0; i < 10; ++i)
254			loop4(i);
255		break;
256
257	case 24:
258		E_KEY[4] = le32_to_cpu(key[4]);
259		t = E_KEY[5] = le32_to_cpu(key[5]);
260		for (i = 0; i < 8; ++i)
261			loop6 (i);
262		break;
263
264	case 32:
265		E_KEY[4] = le32_to_cpu(key[4]);
266		E_KEY[5] = le32_to_cpu(key[5]);
267		E_KEY[6] = le32_to_cpu(key[6]);
268		t = E_KEY[7] = le32_to_cpu(key[7]);
269		for (i = 0; i < 7; ++i)
270			loop8(i);
271		break;
272	}
273
274	D_KEY[0] = E_KEY[key_len + 24];
275	D_KEY[1] = E_KEY[key_len + 25];
276	D_KEY[2] = E_KEY[key_len + 26];
277	D_KEY[3] = E_KEY[key_len + 27];
278
279	for (i = 4; i < key_len + 24; ++i) {
280		j = key_len + 24 - (i & ~3) + (i & 3);
281		imix_col(D_KEY[j], E_KEY[i]);
282	}
283
284	return 0;
285}
286
287asmlinkage void aes_enc_blk(struct crypto_tfm *tfm, u8 *out, const u8 *in);
288asmlinkage void aes_dec_blk(struct crypto_tfm *tfm, u8 *out, const u8 *in);
289
290static void aes_encrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
291{
292	aes_enc_blk(tfm, dst, src);
293}
294
295static void aes_decrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
296{
297	aes_dec_blk(tfm, dst, src);
298}
299
300static struct crypto_alg aes_alg = {
301	.cra_name		=	"aes",
302	.cra_driver_name	=	"aes-x86_64",
303	.cra_priority		=	200,
304	.cra_flags		=	CRYPTO_ALG_TYPE_CIPHER,
305	.cra_blocksize		=	AES_BLOCK_SIZE,
306	.cra_ctxsize		=	sizeof(struct aes_ctx),
307	.cra_module		=	THIS_MODULE,
308	.cra_list		=	LIST_HEAD_INIT(aes_alg.cra_list),
309	.cra_u			=	{
310		.cipher = {
311			.cia_min_keysize	=	AES_MIN_KEY_SIZE,
312			.cia_max_keysize	=	AES_MAX_KEY_SIZE,
313			.cia_setkey	   	= 	aes_set_key,
314			.cia_encrypt	 	=	aes_encrypt,
315			.cia_decrypt	  	=	aes_decrypt
316		}
317	}
318};
319
320static int __init aes_init(void)
321{
322	gen_tabs();
323	return crypto_register_alg(&aes_alg);
324}
325
326static void __exit aes_fini(void)
327{
328	crypto_unregister_alg(&aes_alg);
329}
330
331module_init(aes_init);
332module_exit(aes_fini);
333
334MODULE_DESCRIPTION("Rijndael (AES) Cipher Algorithm");
335MODULE_LICENSE("GPL");
336MODULE_ALIAS("aes");
337