[linux.git] / crypto / twofish_generic.c

/*
 * Twofish for CryptoAPI
 *
 * Originally Twofish for GPG
 * By Matthew Skala <[email protected]>, July 26, 1998
 * 256-bit key length added March 20, 1999
 * Some modifications to reduce the text size by Werner Koch, April, 1998
 * Ported to the kerneli patch by Marc Mutz <[email protected]>
 * Ported to CryptoAPI by Colin Slater <[email protected]>
 *
 * The original author has disclaimed all copyright interest in this
 * code and thus put it in the public domain. The subsequent authors 
 * have put this under the GNU General Public License.
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 *
 * This code is a "clean room" implementation, written from the paper
 * _Twofish: A 128-Bit Block Cipher_ by Bruce Schneier, John Kelsey,
 * Doug Whiting, David Wagner, Chris Hall, and Niels Ferguson, available
 * through http://www.counterpane.com/twofish.html
 *
 * For background information on multiplication in finite fields, used for
 * the matrix operations in the key schedule, see the book _Contemporary
 * Abstract Algebra_ by Joseph A. Gallian, especially chapter 22 in the
 * Third Edition.
 */

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

/* Macros to compute the g() function in the encryption and decryption
 * rounds.  G1 is the straight g() function; G2 includes the 8-bit
 * rotation for the high 32-bit word. */

#define G1(a) \
     (ctx->s[0][(a) & 0xFF]) ^ (ctx->s[1][((a) >> 8) & 0xFF]) \
   ^ (ctx->s[2][((a) >> 16) & 0xFF]) ^ (ctx->s[3][(a) >> 24])

#define G2(b) \
     (ctx->s[1][(b) & 0xFF]) ^ (ctx->s[2][((b) >> 8) & 0xFF]) \
   ^ (ctx->s[3][((b) >> 16) & 0xFF]) ^ (ctx->s[0][(b) >> 24])

/* Encryption and decryption Feistel rounds.  Each one calls the two g()
 * macros, does the PHT, and performs the XOR and the appropriate bit
 * rotations.  The parameters are the round number (used to select subkeys),
 * and the four 32-bit chunks of the text. */

#define ENCROUND(n, a, b, c, d) \
   x = G1 (a); y = G2 (b); \
   x += y; y += x + ctx->k[2 * (n) + 1]; \
   (c) ^= x + ctx->k[2 * (n)]; \
   (c) = ror32((c), 1); \
   (d) = rol32((d), 1) ^ y

#define DECROUND(n, a, b, c, d) \
   x = G1 (a); y = G2 (b); \
   x += y; y += x; \
   (d) ^= y + ctx->k[2 * (n) + 1]; \
   (d) = ror32((d), 1); \
   (c) = rol32((c), 1); \
   (c) ^= (x + ctx->k[2 * (n)])

/* Encryption and decryption cycles; each one is simply two Feistel rounds
 * with the 32-bit chunks re-ordered to simulate the "swap" */

#define ENCCYCLE(n) \
   ENCROUND (2 * (n), a, b, c, d); \
   ENCROUND (2 * (n) + 1, c, d, a, b)

#define DECCYCLE(n) \
   DECROUND (2 * (n) + 1, c, d, a, b); \
   DECROUND (2 * (n), a, b, c, d)

/* Macros to convert the input and output bytes into 32-bit words,
 * and simultaneously perform the whitening step.  INPACK packs word
 * number n into the variable named by x, using whitening subkey number m.
 * OUTUNPACK unpacks word number n from the variable named by x, using
 * whitening subkey number m. */

#define INPACK(n, x, m) \
   x = le32_to_cpu(src[n]) ^ ctx->w[m]

#define OUTUNPACK(n, x, m) \
   x ^= ctx->w[m]; \
   dst[n] = cpu_to_le32(x)


/* Encrypt one block.  in and out may be the same. */
static void twofish_encrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
{
	struct twofish_ctx *ctx = crypto_tfm_ctx(tfm);
	const __le32 *src = (const __le32 *)in;
	__le32 *dst = (__le32 *)out;

	/* The four 32-bit chunks of the text. */
	u32 a, b, c, d;
	
	/* Temporaries used by the round function. */
	u32 x, y;

	/* Input whitening and packing. */
	INPACK (0, a, 0);
	INPACK (1, b, 1);
	INPACK (2, c, 2);
	INPACK (3, d, 3);
	
	/* Encryption Feistel cycles. */
	ENCCYCLE (0);
	ENCCYCLE (1);
	ENCCYCLE (2);
	ENCCYCLE (3);
	ENCCYCLE (4);
	ENCCYCLE (5);
	ENCCYCLE (6);
	ENCCYCLE (7);
	
	/* Output whitening and unpacking. */
	OUTUNPACK (0, c, 4);
	OUTUNPACK (1, d, 5);
	OUTUNPACK (2, a, 6);
	OUTUNPACK (3, b, 7);
	
}

/* Decrypt one block.  in and out may be the same. */
static void twofish_decrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
{
	struct twofish_ctx *ctx = crypto_tfm_ctx(tfm);
	const __le32 *src = (const __le32 *)in;
	__le32 *dst = (__le32 *)out;
  
	/* The four 32-bit chunks of the text. */
	u32 a, b, c, d;
	
	/* Temporaries used by the round function. */
	u32 x, y;
	
	/* Input whitening and packing. */
	INPACK (0, c, 4);
	INPACK (1, d, 5);
	INPACK (2, a, 6);
	INPACK (3, b, 7);
	
	/* Encryption Feistel cycles. */
	DECCYCLE (7);
	DECCYCLE (6);
	DECCYCLE (5);
	DECCYCLE (4);
	DECCYCLE (3);
	DECCYCLE (2);
	DECCYCLE (1);
	DECCYCLE (0);

	/* Output whitening and unpacking. */
	OUTUNPACK (0, a, 0);
	OUTUNPACK (1, b, 1);
	OUTUNPACK (2, c, 2);
	OUTUNPACK (3, d, 3);

}

static struct crypto_alg alg = {
	.cra_name           =   "twofish",
	.cra_driver_name    =   "twofish-generic",
	.cra_priority       =   100,
	.cra_flags          =   CRYPTO_ALG_TYPE_CIPHER,
	.cra_blocksize      =   TF_BLOCK_SIZE,
	.cra_ctxsize        =   sizeof(struct twofish_ctx),
	.cra_alignmask      =	3,
	.cra_module         =   THIS_MODULE,
	.cra_u              =   { .cipher = {
	.cia_min_keysize    =   TF_MIN_KEY_SIZE,
	.cia_max_keysize    =   TF_MAX_KEY_SIZE,
	.cia_setkey         =   twofish_setkey,
	.cia_encrypt        =   twofish_encrypt,
	.cia_decrypt        =   twofish_decrypt } }
};

static int __init twofish_mod_init(void)
{
	return crypto_register_alg(&alg);
}

static void __exit twofish_mod_fini(void)
{
	crypto_unregister_alg(&alg);
}

module_init(twofish_mod_init);
module_exit(twofish_mod_fini);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION ("Twofish Cipher Algorithm");
MODULE_ALIAS_CRYPTO("twofish");
MODULE_ALIAS_CRYPTO("twofish-generic");
Commit	Line	Data
1da177e4 LT	1	/*
	2	* Twofish for CryptoAPI
	3	*
	4	* Originally Twofish for GPG
	5	* By Matthew Skala <[email protected]>, July 26, 1998
	6	* 256-bit key length added March 20, 1999
	7	* Some modifications to reduce the text size by Werner Koch, April, 1998
	8	* Ported to the kerneli patch by Marc Mutz <[email protected]>
	9	* Ported to CryptoAPI by Colin Slater <[email protected]>
	10	*
	11	* The original author has disclaimed all copyright interest in this
	12	* code and thus put it in the public domain. The subsequent authors
	13	* have put this under the GNU General Public License.
	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	* This program is distributed in the hope that it will be useful,
	21	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	22	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	23	* GNU General Public License for more details.
	24	*
	25	* You should have received a copy of the GNU General Public License
1af39daa MK	26	* along with this program. If not, see <http://www.gnu.org/licenses/>.
1af39daa MK	27	*
1da177e4 LT	28	*
	29	* This code is a "clean room" implementation, written from the paper
	30	* _Twofish: A 128-Bit Block Cipher_ by Bruce Schneier, John Kelsey,
	31	* Doug Whiting, David Wagner, Chris Hall, and Niels Ferguson, available
	32	* through http://www.counterpane.com/twofish.html
	33	*
	34	* For background information on multiplication in finite fields, used for
	35	* the matrix operations in the key schedule, see the book _Contemporary
	36	* Abstract Algebra_ by Joseph A. Gallian, especially chapter 22 in the
	37	* Third Edition.
	38	*/
06ace7a9 HX	39
06ace7a9 HX	40	#include <asm/byteorder.h>
2729bb42	41	#include <crypto/twofish.h>
1da177e4 LT	42	#include <linux/module.h>
	43	#include <linux/init.h>
	44	#include <linux/types.h>
	45	#include <linux/errno.h>
	46	#include <linux/crypto.h>
a5f8c473	47	#include <linux/bitops.h>
1da177e4	48
1da177e4 LT	49	/* Macros to compute the g() function in the encryption and decryption
	50	* rounds. G1 is the straight g() function; G2 includes the 8-bit
	51	* rotation for the high 32-bit word. */
	52
	53	#define G1(a) \
	54	(ctx->s[0][(a) & 0xFF]) ^ (ctx->s[1][((a) >> 8) & 0xFF]) \
	55	^ (ctx->s[2][((a) >> 16) & 0xFF]) ^ (ctx->s[3][(a) >> 24])
	56
	57	#define G2(b) \
	58	(ctx->s[1][(b) & 0xFF]) ^ (ctx->s[2][((b) >> 8) & 0xFF]) \
	59	^ (ctx->s[3][((b) >> 16) & 0xFF]) ^ (ctx->s[0][(b) >> 24])
	60
	61	/* Encryption and decryption Feistel rounds. Each one calls the two g()
	62	* macros, does the PHT, and performs the XOR and the appropriate bit
	63	* rotations. The parameters are the round number (used to select subkeys),
	64	* and the four 32-bit chunks of the text. */
	65
	66	#define ENCROUND(n, a, b, c, d) \
	67	x = G1 (a); y = G2 (b); \
	68	x += y; y += x + ctx->k[2 * (n) + 1]; \
	69	(c) ^= x + ctx->k[2 * (n)]; \
a5f8c473 DV	70	(c) = ror32((c), 1); \
a5f8c473 DV	71	(d) = rol32((d), 1) ^ y
1da177e4 LT	72
	73	#define DECROUND(n, a, b, c, d) \
	74	x = G1 (a); y = G2 (b); \
	75	x += y; y += x; \
	76	(d) ^= y + ctx->k[2 * (n) + 1]; \
a5f8c473 DV	77	(d) = ror32((d), 1); \
a5f8c473 DV	78	(c) = rol32((c), 1); \
1da177e4 LT	79	(c) ^= (x + ctx->k[2 * (n)])
	80
	81	/* Encryption and decryption cycles; each one is simply two Feistel rounds
	82	* with the 32-bit chunks re-ordered to simulate the "swap" */
	83
	84	#define ENCCYCLE(n) \
	85	ENCROUND (2 * (n), a, b, c, d); \
	86	ENCROUND (2 * (n) + 1, c, d, a, b)
	87
	88	#define DECCYCLE(n) \
	89	DECROUND (2 * (n) + 1, c, d, a, b); \
	90	DECROUND (2 * (n), a, b, c, d)
	91
	92	/* Macros to convert the input and output bytes into 32-bit words,
	93	* and simultaneously perform the whitening step. INPACK packs word
	94	* number n into the variable named by x, using whitening subkey number m.
	95	* OUTUNPACK unpacks word number n from the variable named by x, using
	96	* whitening subkey number m. */
	97
	98	#define INPACK(n, x, m) \
06ace7a9	99	x = le32_to_cpu(src[n]) ^ ctx->w[m]
1da177e4 LT	100
	101	#define OUTUNPACK(n, x, m) \
	102	x ^= ctx->w[m]; \
06ace7a9	103	dst[n] = cpu_to_le32(x)
1da177e4	104
1da177e4	105
1da177e4 LT	106
1da177e4 LT	107	/* Encrypt one block. in and out may be the same. */
6c2bb98b	108	static void twofish_encrypt(struct crypto_tfm tfm, u8 out, const u8 *in)
1da177e4	109	{
6c2bb98b	110	struct twofish_ctx *ctx = crypto_tfm_ctx(tfm);
06ace7a9 HX	111	const __le32 src = (const __le32 )in;
06ace7a9 HX	112	__le32 dst = (__le32 )out;
1da177e4 LT	113
	114	/* The four 32-bit chunks of the text. */
	115	u32 a, b, c, d;
	116
	117	/* Temporaries used by the round function. */
	118	u32 x, y;
	119
	120	/* Input whitening and packing. */
	121	INPACK (0, a, 0);
	122	INPACK (1, b, 1);
	123	INPACK (2, c, 2);
	124	INPACK (3, d, 3);
	125
	126	/* Encryption Feistel cycles. */
	127	ENCCYCLE (0);
	128	ENCCYCLE (1);
	129	ENCCYCLE (2);
	130	ENCCYCLE (3);
	131	ENCCYCLE (4);
	132	ENCCYCLE (5);
	133	ENCCYCLE (6);
	134	ENCCYCLE (7);
	135
	136	/* Output whitening and unpacking. */
	137	OUTUNPACK (0, c, 4);
	138	OUTUNPACK (1, d, 5);
	139	OUTUNPACK (2, a, 6);
	140	OUTUNPACK (3, b, 7);
	141
	142	}
	143
	144	/* Decrypt one block. in and out may be the same. */
6c2bb98b	145	static void twofish_decrypt(struct crypto_tfm tfm, u8 out, const u8 *in)
1da177e4	146	{
6c2bb98b	147	struct twofish_ctx *ctx = crypto_tfm_ctx(tfm);
06ace7a9 HX	148	const __le32 src = (const __le32 )in;
06ace7a9 HX	149	__le32 dst = (__le32 )out;
1da177e4 LT	150
	151	/* The four 32-bit chunks of the text. */
	152	u32 a, b, c, d;
	153
	154	/* Temporaries used by the round function. */
	155	u32 x, y;
	156
	157	/* Input whitening and packing. */
	158	INPACK (0, c, 4);
	159	INPACK (1, d, 5);
	160	INPACK (2, a, 6);
	161	INPACK (3, b, 7);
	162
	163	/* Encryption Feistel cycles. */
	164	DECCYCLE (7);
	165	DECCYCLE (6);
	166	DECCYCLE (5);
	167	DECCYCLE (4);
	168	DECCYCLE (3);
	169	DECCYCLE (2);
	170	DECCYCLE (1);
	171	DECCYCLE (0);
	172
	173	/* Output whitening and unpacking. */
	174	OUTUNPACK (0, a, 0);
	175	OUTUNPACK (1, b, 1);
	176	OUTUNPACK (2, c, 2);
	177	OUTUNPACK (3, d, 3);
	178
	179	}
	180
	181	static struct crypto_alg alg = {
	182	.cra_name = "twofish",
758f570e JF	183	.cra_driver_name = "twofish-generic",
758f570e JF	184	.cra_priority = 100,
1da177e4 LT	185	.cra_flags = CRYPTO_ALG_TYPE_CIPHER,
	186	.cra_blocksize = TF_BLOCK_SIZE,
	187	.cra_ctxsize = sizeof(struct twofish_ctx),
a429d260	188	.cra_alignmask = 3,
1da177e4	189	.cra_module = THIS_MODULE,
1da177e4 LT	190	.cra_u = { .cipher = {
	191	.cia_min_keysize = TF_MIN_KEY_SIZE,
	192	.cia_max_keysize = TF_MAX_KEY_SIZE,
	193	.cia_setkey = twofish_setkey,
	194	.cia_encrypt = twofish_encrypt,
	195	.cia_decrypt = twofish_decrypt } }
	196	};
	197
3af5b90b	198	static int __init twofish_mod_init(void)
1da177e4 LT	199	{
	200	return crypto_register_alg(&alg);
	201	}
	202
3af5b90b	203	static void __exit twofish_mod_fini(void)
1da177e4 LT	204	{
	205	crypto_unregister_alg(&alg);
	206	}
	207
3af5b90b KB	208	module_init(twofish_mod_init);
3af5b90b KB	209	module_exit(twofish_mod_fini);
1da177e4 LT	210
	211	MODULE_LICENSE("GPL");
	212	MODULE_DESCRIPTION ("Twofish Cipher Algorithm");
5d26a105	213	MODULE_ALIAS_CRYPTO("twofish");
3e14dcf7	214	MODULE_ALIAS_CRYPTO("twofish-generic");