[linux-2.6-block.git] / crypto / salsa20_generic.c

/*
 * Salsa20: Salsa20 stream cipher algorithm
 *
 * Copyright (c) 2007 Tan Swee Heng <thesweeheng@gmail.com>
 *
 * Derived from:
 * - salsa20.c: Public domain C code by Daniel J. Bernstein <djb@cr.yp.to>
 *
 * Salsa20 is a stream cipher candidate in eSTREAM, the ECRYPT Stream
 * Cipher Project. It is designed by Daniel J. Bernstein <djb@cr.yp.to>.
 * More information about eSTREAM and Salsa20 can be found here:
 *   http://www.ecrypt.eu.org/stream/
 *   http://cr.yp.to/snuffle.html
 *
 * 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.
 *
 */

#include <asm/unaligned.h>
#include <crypto/internal/skcipher.h>
#include <crypto/salsa20.h>
#include <linux/module.h>

static void salsa20_block(u32 *state, __le32 *stream)
{
	u32 x[16];
	int i;

	memcpy(x, state, sizeof(x));

	for (i = 0; i < 20; i += 2) {
		x[ 4] ^= rol32((x[ 0] + x[12]),  7);
		x[ 8] ^= rol32((x[ 4] + x[ 0]),  9);
		x[12] ^= rol32((x[ 8] + x[ 4]), 13);
		x[ 0] ^= rol32((x[12] + x[ 8]), 18);
		x[ 9] ^= rol32((x[ 5] + x[ 1]),  7);
		x[13] ^= rol32((x[ 9] + x[ 5]),  9);
		x[ 1] ^= rol32((x[13] + x[ 9]), 13);
		x[ 5] ^= rol32((x[ 1] + x[13]), 18);
		x[14] ^= rol32((x[10] + x[ 6]),  7);
		x[ 2] ^= rol32((x[14] + x[10]),  9);
		x[ 6] ^= rol32((x[ 2] + x[14]), 13);
		x[10] ^= rol32((x[ 6] + x[ 2]), 18);
		x[ 3] ^= rol32((x[15] + x[11]),  7);
		x[ 7] ^= rol32((x[ 3] + x[15]),  9);
		x[11] ^= rol32((x[ 7] + x[ 3]), 13);
		x[15] ^= rol32((x[11] + x[ 7]), 18);
		x[ 1] ^= rol32((x[ 0] + x[ 3]),  7);
		x[ 2] ^= rol32((x[ 1] + x[ 0]),  9);
		x[ 3] ^= rol32((x[ 2] + x[ 1]), 13);
		x[ 0] ^= rol32((x[ 3] + x[ 2]), 18);
		x[ 6] ^= rol32((x[ 5] + x[ 4]),  7);
		x[ 7] ^= rol32((x[ 6] + x[ 5]),  9);
		x[ 4] ^= rol32((x[ 7] + x[ 6]), 13);
		x[ 5] ^= rol32((x[ 4] + x[ 7]), 18);
		x[11] ^= rol32((x[10] + x[ 9]),  7);
		x[ 8] ^= rol32((x[11] + x[10]),  9);
		x[ 9] ^= rol32((x[ 8] + x[11]), 13);
		x[10] ^= rol32((x[ 9] + x[ 8]), 18);
		x[12] ^= rol32((x[15] + x[14]),  7);
		x[13] ^= rol32((x[12] + x[15]),  9);
		x[14] ^= rol32((x[13] + x[12]), 13);
		x[15] ^= rol32((x[14] + x[13]), 18);
	}

	for (i = 0; i < 16; i++)
		stream[i] = cpu_to_le32(x[i] + state[i]);

	if (++state[8] == 0)
		state[9]++;
}

static void salsa20_docrypt(u32 *state, u8 *dst, const u8 *src,
			    unsigned int bytes)
{
	__le32 stream[SALSA20_BLOCK_SIZE / sizeof(__le32)];

	if (dst != src)
		memcpy(dst, src, bytes);

	while (bytes >= SALSA20_BLOCK_SIZE) {
		salsa20_block(state, stream);
		crypto_xor(dst, (const u8 *)stream, SALSA20_BLOCK_SIZE);
		bytes -= SALSA20_BLOCK_SIZE;
		dst += SALSA20_BLOCK_SIZE;
	}
	if (bytes) {
		salsa20_block(state, stream);
		crypto_xor(dst, (const u8 *)stream, bytes);
	}
}

void crypto_salsa20_init(u32 *state, const struct salsa20_ctx *ctx,
			 const u8 *iv)
{
	memcpy(state, ctx->initial_state, sizeof(ctx->initial_state));
	state[6] = get_unaligned_le32(iv + 0);
	state[7] = get_unaligned_le32(iv + 4);
}
EXPORT_SYMBOL_GPL(crypto_salsa20_init);

int crypto_salsa20_setkey(struct crypto_skcipher *tfm, const u8 *key,
			  unsigned int keysize)
{
	static const char sigma[16] = "expand 32-byte k";
	static const char tau[16] = "expand 16-byte k";
	struct salsa20_ctx *ctx = crypto_skcipher_ctx(tfm);
	const char *constants;

	if (keysize != SALSA20_MIN_KEY_SIZE &&
	    keysize != SALSA20_MAX_KEY_SIZE)
		return -EINVAL;

	ctx->initial_state[1] = get_unaligned_le32(key + 0);
	ctx->initial_state[2] = get_unaligned_le32(key + 4);
	ctx->initial_state[3] = get_unaligned_le32(key + 8);
	ctx->initial_state[4] = get_unaligned_le32(key + 12);
	if (keysize == 32) { /* recommended */
		key += 16;
		constants = sigma;
	} else { /* keysize == 16 */
		constants = tau;
	}
	ctx->initial_state[11] = get_unaligned_le32(key + 0);
	ctx->initial_state[12] = get_unaligned_le32(key + 4);
	ctx->initial_state[13] = get_unaligned_le32(key + 8);
	ctx->initial_state[14] = get_unaligned_le32(key + 12);
	ctx->initial_state[0]  = get_unaligned_le32(constants + 0);
	ctx->initial_state[5]  = get_unaligned_le32(constants + 4);
	ctx->initial_state[10] = get_unaligned_le32(constants + 8);
	ctx->initial_state[15] = get_unaligned_le32(constants + 12);

	/* space for the nonce; it will be overridden for each request */
	ctx->initial_state[6] = 0;
	ctx->initial_state[7] = 0;

	/* initial block number */
	ctx->initial_state[8] = 0;
	ctx->initial_state[9] = 0;

	return 0;
}
EXPORT_SYMBOL_GPL(crypto_salsa20_setkey);

static int salsa20_crypt(struct skcipher_request *req)
{
	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
	const struct salsa20_ctx *ctx = crypto_skcipher_ctx(tfm);
	struct skcipher_walk walk;
	u32 state[16];
	int err;

	err = skcipher_walk_virt(&walk, req, true);

	crypto_salsa20_init(state, ctx, walk.iv);

	while (walk.nbytes > 0) {
		unsigned int nbytes = walk.nbytes;

		if (nbytes < walk.total)
			nbytes = round_down(nbytes, walk.stride);

		salsa20_docrypt(state, walk.dst.virt.addr, walk.src.virt.addr,
				nbytes);
		err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
	}

	return err;
}

static struct skcipher_alg alg = {
	.base.cra_name		= "salsa20",
	.base.cra_driver_name	= "salsa20-generic",
	.base.cra_priority	= 100,
	.base.cra_blocksize	= 1,
	.base.cra_ctxsize	= sizeof(struct salsa20_ctx),
	.base.cra_module	= THIS_MODULE,

	.min_keysize		= SALSA20_MIN_KEY_SIZE,
	.max_keysize		= SALSA20_MAX_KEY_SIZE,
	.ivsize			= SALSA20_IV_SIZE,
	.chunksize		= SALSA20_BLOCK_SIZE,
	.setkey			= crypto_salsa20_setkey,
	.encrypt		= salsa20_crypt,
	.decrypt		= salsa20_crypt,
};

static int __init salsa20_generic_mod_init(void)
{
	return crypto_register_skcipher(&alg);
}

static void __exit salsa20_generic_mod_fini(void)
{
	crypto_unregister_skcipher(&alg);
}

module_init(salsa20_generic_mod_init);
module_exit(salsa20_generic_mod_fini);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION ("Salsa20 stream cipher algorithm");
MODULE_ALIAS_CRYPTO("salsa20");
MODULE_ALIAS_CRYPTO("salsa20-generic");
Commit	Line	Data
2407d608 TSH	1	/*
	2	* Salsa20: Salsa20 stream cipher algorithm
	3	*
	4	* Copyright (c) 2007 Tan Swee Heng <thesweeheng@gmail.com>
	5	*
	6	* Derived from:
	7	* - salsa20.c: Public domain C code by Daniel J. Bernstein <djb@cr.yp.to>
	8	*
	9	* Salsa20 is a stream cipher candidate in eSTREAM, the ECRYPT Stream
	10	* Cipher Project. It is designed by Daniel J. Bernstein <djb@cr.yp.to>.
	11	* More information about eSTREAM and Salsa20 can be found here:
	12	* http://www.ecrypt.eu.org/stream/
	13	* http://cr.yp.to/snuffle.html
	14	*
	15	* This program is free software; you can redistribute it and/or modify it
	16	* under the terms of the GNU General Public License as published by the Free
	17	* Software Foundation; either version 2 of the License, or (at your option)
	18	* any later version.
	19	*
	20	*/
	21
b62b3db7 EB	22	#include <asm/unaligned.h>
b62b3db7 EB	23	#include <crypto/internal/skcipher.h>
eb772f37	24	#include <crypto/salsa20.h>
2407d608	25	#include <linux/module.h>
2407d608	26
b62b3db7	27	static void salsa20_block(u32 state, __le32 stream)
2407d608 TSH	28	{
	29	u32 x[16];
	30	int i;
	31
b62b3db7 EB	32	memcpy(x, state, sizeof(x));
	33
	34	for (i = 0; i < 20; i += 2) {
f0d1ec3a HH	35	x[ 4] ^= rol32((x[ 0] + x[12]), 7);
	36	x[ 8] ^= rol32((x[ 4] + x[ 0]), 9);
	37	x[12] ^= rol32((x[ 8] + x[ 4]), 13);
	38	x[ 0] ^= rol32((x[12] + x[ 8]), 18);
	39	x[ 9] ^= rol32((x[ 5] + x[ 1]), 7);
	40	x[13] ^= rol32((x[ 9] + x[ 5]), 9);
	41	x[ 1] ^= rol32((x[13] + x[ 9]), 13);
	42	x[ 5] ^= rol32((x[ 1] + x[13]), 18);
	43	x[14] ^= rol32((x[10] + x[ 6]), 7);
	44	x[ 2] ^= rol32((x[14] + x[10]), 9);
	45	x[ 6] ^= rol32((x[ 2] + x[14]), 13);
	46	x[10] ^= rol32((x[ 6] + x[ 2]), 18);
	47	x[ 3] ^= rol32((x[15] + x[11]), 7);
	48	x[ 7] ^= rol32((x[ 3] + x[15]), 9);
	49	x[11] ^= rol32((x[ 7] + x[ 3]), 13);
	50	x[15] ^= rol32((x[11] + x[ 7]), 18);
	51	x[ 1] ^= rol32((x[ 0] + x[ 3]), 7);
	52	x[ 2] ^= rol32((x[ 1] + x[ 0]), 9);
	53	x[ 3] ^= rol32((x[ 2] + x[ 1]), 13);
	54	x[ 0] ^= rol32((x[ 3] + x[ 2]), 18);
	55	x[ 6] ^= rol32((x[ 5] + x[ 4]), 7);
	56	x[ 7] ^= rol32((x[ 6] + x[ 5]), 9);
	57	x[ 4] ^= rol32((x[ 7] + x[ 6]), 13);
	58	x[ 5] ^= rol32((x[ 4] + x[ 7]), 18);
	59	x[11] ^= rol32((x[10] + x[ 9]), 7);
	60	x[ 8] ^= rol32((x[11] + x[10]), 9);
	61	x[ 9] ^= rol32((x[ 8] + x[11]), 13);
	62	x[10] ^= rol32((x[ 9] + x[ 8]), 18);
	63	x[12] ^= rol32((x[15] + x[14]), 7);
	64	x[13] ^= rol32((x[12] + x[15]), 9);
	65	x[14] ^= rol32((x[13] + x[12]), 13);
	66	x[15] ^= rol32((x[14] + x[13]), 18);
2407d608	67	}
2407d608	68
b62b3db7 EB	69	for (i = 0; i < 16; i++)
	70	stream[i] = cpu_to_le32(x[i] + state[i]);
	71
	72	if (++state[8] == 0)
	73	state[9]++;
	74	}
2407d608	75
b62b3db7 EB	76	static void salsa20_docrypt(u32 state, u8 dst, const u8 *src,
b62b3db7 EB	77	unsigned int bytes)
2407d608	78	{
b62b3db7	79	__le32 stream[SALSA20_BLOCK_SIZE / sizeof(__le32)];
2407d608	80
b62b3db7 EB	81	if (dst != src)
	82	memcpy(dst, src, bytes);
	83
	84	while (bytes >= SALSA20_BLOCK_SIZE) {
	85	salsa20_block(state, stream);
	86	crypto_xor(dst, (const u8 *)stream, SALSA20_BLOCK_SIZE);
	87	bytes -= SALSA20_BLOCK_SIZE;
	88	dst += SALSA20_BLOCK_SIZE;
	89	}
	90	if (bytes) {
	91	salsa20_block(state, stream);
	92	crypto_xor(dst, (const u8 *)stream, bytes);
2407d608	93	}
2407d608 TSH	94	}
2407d608 TSH	95
eb772f37	96	void crypto_salsa20_init(u32 state, const struct salsa20_ctx ctx,
b62b3db7	97	const u8 *iv)
2407d608	98	{
b62b3db7 EB	99	memcpy(state, ctx->initial_state, sizeof(ctx->initial_state));
	100	state[6] = get_unaligned_le32(iv + 0);
	101	state[7] = get_unaligned_le32(iv + 4);
2407d608	102	}
eb772f37	103	EXPORT_SYMBOL_GPL(crypto_salsa20_init);
2407d608	104
eb772f37	105	int crypto_salsa20_setkey(struct crypto_skcipher tfm, const u8 key,
b62b3db7	106	unsigned int keysize)
2407d608	107	{
b62b3db7 EB	108	static const char sigma[16] = "expand 32-byte k";
	109	static const char tau[16] = "expand 16-byte k";
	110	struct salsa20_ctx *ctx = crypto_skcipher_ctx(tfm);
	111	const char *constants;
2407d608	112
b62b3db7 EB	113	if (keysize != SALSA20_MIN_KEY_SIZE &&
	114	keysize != SALSA20_MAX_KEY_SIZE)
	115	return -EINVAL;
2407d608	116
b62b3db7 EB	117	ctx->initial_state[1] = get_unaligned_le32(key + 0);
	118	ctx->initial_state[2] = get_unaligned_le32(key + 4);
	119	ctx->initial_state[3] = get_unaligned_le32(key + 8);
	120	ctx->initial_state[4] = get_unaligned_le32(key + 12);
	121	if (keysize == 32) { /* recommended */
	122	key += 16;
	123	constants = sigma;
	124	} else { /* keysize == 16 */
	125	constants = tau;
2407d608	126	}
b62b3db7 EB	127	ctx->initial_state[11] = get_unaligned_le32(key + 0);
	128	ctx->initial_state[12] = get_unaligned_le32(key + 4);
	129	ctx->initial_state[13] = get_unaligned_le32(key + 8);
	130	ctx->initial_state[14] = get_unaligned_le32(key + 12);
	131	ctx->initial_state[0] = get_unaligned_le32(constants + 0);
	132	ctx->initial_state[5] = get_unaligned_le32(constants + 4);
	133	ctx->initial_state[10] = get_unaligned_le32(constants + 8);
	134	ctx->initial_state[15] = get_unaligned_le32(constants + 12);
	135
	136	/* space for the nonce; it will be overridden for each request */
	137	ctx->initial_state[6] = 0;
	138	ctx->initial_state[7] = 0;
	139
	140	/* initial block number */
	141	ctx->initial_state[8] = 0;
	142	ctx->initial_state[9] = 0;
2407d608	143
2407d608 TSH	144	return 0;
2407d608 TSH	145	}
eb772f37	146	EXPORT_SYMBOL_GPL(crypto_salsa20_setkey);
2407d608	147
b62b3db7	148	static int salsa20_crypt(struct skcipher_request *req)
2407d608	149	{
b62b3db7 EB	150	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
	151	const struct salsa20_ctx *ctx = crypto_skcipher_ctx(tfm);
	152	struct skcipher_walk walk;
	153	u32 state[16];
2407d608 TSH	154	int err;
2407d608 TSH	155
b62b3db7	156	err = skcipher_walk_virt(&walk, req, true);
2407d608	157
eb772f37	158	crypto_salsa20_init(state, ctx, walk.iv);
2407d608	159
b62b3db7 EB	160	while (walk.nbytes > 0) {
b62b3db7 EB	161	unsigned int nbytes = walk.nbytes;
eb6f13eb	162
b62b3db7 EB	163	if (nbytes < walk.total)
	164	nbytes = round_down(nbytes, walk.stride);
	165
	166	salsa20_docrypt(state, walk.dst.virt.addr, walk.src.virt.addr,
	167	nbytes);
	168	err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
eb6f13eb TSH	169	}
eb6f13eb TSH	170
2407d608 TSH	171	return err;
	172	}
	173
b62b3db7 EB	174	static struct skcipher_alg alg = {
	175	.base.cra_name = "salsa20",
	176	.base.cra_driver_name = "salsa20-generic",
	177	.base.cra_priority = 100,
	178	.base.cra_blocksize = 1,
	179	.base.cra_ctxsize = sizeof(struct salsa20_ctx),
	180	.base.cra_module = THIS_MODULE,
	181
	182	.min_keysize = SALSA20_MIN_KEY_SIZE,
	183	.max_keysize = SALSA20_MAX_KEY_SIZE,
	184	.ivsize = SALSA20_IV_SIZE,
	185	.chunksize = SALSA20_BLOCK_SIZE,
eb772f37	186	.setkey = crypto_salsa20_setkey,
b62b3db7 EB	187	.encrypt = salsa20_crypt,
b62b3db7 EB	188	.decrypt = salsa20_crypt,
2407d608 TSH	189	};
2407d608 TSH	190
3af5b90b	191	static int __init salsa20_generic_mod_init(void)
2407d608	192	{
b62b3db7	193	return crypto_register_skcipher(&alg);
2407d608 TSH	194	}
2407d608 TSH	195
3af5b90b	196	static void __exit salsa20_generic_mod_fini(void)
2407d608	197	{
b62b3db7	198	crypto_unregister_skcipher(&alg);
2407d608 TSH	199	}
2407d608 TSH	200
3af5b90b KB	201	module_init(salsa20_generic_mod_init);
3af5b90b KB	202	module_exit(salsa20_generic_mod_fini);
2407d608 TSH	203
	204	MODULE_LICENSE("GPL");
	205	MODULE_DESCRIPTION ("Salsa20 stream cipher algorithm");
5d26a105	206	MODULE_ALIAS_CRYPTO("salsa20");
3e14dcf7	207	MODULE_ALIAS_CRYPTO("salsa20-generic");