[linux-2.6-block.git] / crypto / arc4.c

/*
 * Cryptographic API
 *
 * ARC4 Cipher Algorithm
 *
 * Jon Oberheide <jon@oberheide.org>
 *
 * 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 <linux/module.h>
#include <linux/init.h>
#include <linux/crypto.h>
#include <crypto/algapi.h>

#define ARC4_MIN_KEY_SIZE	1
#define ARC4_MAX_KEY_SIZE	256
#define ARC4_BLOCK_SIZE		1

struct arc4_ctx {
	u32 S[256];
	u32 x, y;
};

static int arc4_set_key(struct crypto_tfm *tfm, const u8 *in_key,
			unsigned int key_len)
{
	struct arc4_ctx *ctx = crypto_tfm_ctx(tfm);
	int i, j = 0, k = 0;

	ctx->x = 1;
	ctx->y = 0;

	for (i = 0; i < 256; i++)
		ctx->S[i] = i;

	for (i = 0; i < 256; i++) {
		u32 a = ctx->S[i];
		j = (j + in_key[k] + a) & 0xff;
		ctx->S[i] = ctx->S[j];
		ctx->S[j] = a;
		if (++k >= key_len)
			k = 0;
	}

	return 0;
}

static void arc4_crypt(struct arc4_ctx *ctx, u8 *out, const u8 *in,
		       unsigned int len)
{
	u32 *const S = ctx->S;
	u32 x, y, a, b;
	u32 ty, ta, tb;

	if (len == 0)
		return;

	x = ctx->x;
	y = ctx->y;

	a = S[x];
	y = (y + a) & 0xff;
	b = S[y];

	do {
		S[y] = a;
		a = (a + b) & 0xff;
		S[x] = b;
		x = (x + 1) & 0xff;
		ta = S[x];
		ty = (y + ta) & 0xff;
		tb = S[ty];
		*out++ = *in++ ^ S[a];
		if (--len == 0)
			break;
		y = ty;
		a = ta;
		b = tb;
	} while (true);

	ctx->x = x;
	ctx->y = y;
}

static void arc4_crypt_one(struct crypto_tfm *tfm, u8 *out, const u8 *in)
{
	arc4_crypt(crypto_tfm_ctx(tfm), out, in, 1);
}

static int ecb_arc4_crypt(struct blkcipher_desc *desc, struct scatterlist *dst,
			  struct scatterlist *src, unsigned int nbytes)
{
	struct arc4_ctx *ctx = crypto_blkcipher_ctx(desc->tfm);
	struct blkcipher_walk walk;
	int err;

	blkcipher_walk_init(&walk, dst, src, nbytes);

	err = blkcipher_walk_virt(desc, &walk);

	while (walk.nbytes > 0) {
		u8 *wsrc = walk.src.virt.addr;
		u8 *wdst = walk.dst.virt.addr;

		arc4_crypt(ctx, wdst, wsrc, walk.nbytes);

		err = blkcipher_walk_done(desc, &walk, 0);
	}

	return err;
}

static struct crypto_alg arc4_algs[2] = { {
	.cra_name		=	"arc4",
	.cra_flags		=	CRYPTO_ALG_TYPE_CIPHER,
	.cra_blocksize		=	ARC4_BLOCK_SIZE,
	.cra_ctxsize		=	sizeof(struct arc4_ctx),
	.cra_module		=	THIS_MODULE,
	.cra_u			=	{
		.cipher = {
			.cia_min_keysize	=	ARC4_MIN_KEY_SIZE,
			.cia_max_keysize	=	ARC4_MAX_KEY_SIZE,
			.cia_setkey		=	arc4_set_key,
			.cia_encrypt		=	arc4_crypt_one,
			.cia_decrypt		=	arc4_crypt_one,
		},
	},
}, {
	.cra_name		=	"ecb(arc4)",
	.cra_priority		=	100,
	.cra_flags		=	CRYPTO_ALG_TYPE_BLKCIPHER,
	.cra_blocksize		=	ARC4_BLOCK_SIZE,
	.cra_ctxsize		=	sizeof(struct arc4_ctx),
	.cra_alignmask		=	0,
	.cra_type		=	&crypto_blkcipher_type,
	.cra_module		=	THIS_MODULE,
	.cra_u			=	{
		.blkcipher = {
			.min_keysize	=	ARC4_MIN_KEY_SIZE,
			.max_keysize	=	ARC4_MAX_KEY_SIZE,
			.setkey		=	arc4_set_key,
			.encrypt	=	ecb_arc4_crypt,
			.decrypt	=	ecb_arc4_crypt,
		},
	},
} };

static int __init arc4_init(void)
{
	return crypto_register_algs(arc4_algs, ARRAY_SIZE(arc4_algs));
}

static void __exit arc4_exit(void)
{
	crypto_unregister_algs(arc4_algs, ARRAY_SIZE(arc4_algs));
}

module_init(arc4_init);
module_exit(arc4_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("ARC4 Cipher Algorithm");
MODULE_AUTHOR("Jon Oberheide <jon@oberheide.org>");
MODULE_ALIAS_CRYPTO("arc4");
Commit	Line	Data
cfa2b54e	1	/*
1da177e4 LT	2	* Cryptographic API
	3	*
	4	* ARC4 Cipher Algorithm
	5	*
	6	* Jon Oberheide <jon@oberheide.org>
	7	*
	8	* This program is free software; you can redistribute it and/or modify
	9	* it under the terms of the GNU General Public License as published by
	10	* the Free Software Foundation; either version 2 of the License, or
	11	* (at your option) any later version.
	12	*
	13	*/
ce6dd368	14
1da177e4 LT	15	#include <linux/module.h>
	16	#include <linux/init.h>
	17	#include <linux/crypto.h>
ce6dd368	18	#include <crypto/algapi.h>
1da177e4 LT	19
	20	#define ARC4_MIN_KEY_SIZE 1
	21	#define ARC4_MAX_KEY_SIZE 256
	22	#define ARC4_BLOCK_SIZE 1
	23
	24	struct arc4_ctx {
d366db60 JK	25	u32 S[256];
d366db60 JK	26	u32 x, y;
1da177e4 LT	27	};
1da177e4 LT	28
6c2bb98b	29	static int arc4_set_key(struct crypto_tfm tfm, const u8 in_key,
560c06ae	30	unsigned int key_len)
1da177e4	31	{
6c2bb98b	32	struct arc4_ctx *ctx = crypto_tfm_ctx(tfm);
1da177e4 LT	33	int i, j = 0, k = 0;
	34
	35	ctx->x = 1;
	36	ctx->y = 0;
	37
cfa2b54e	38	for (i = 0; i < 256; i++)
1da177e4 LT	39	ctx->S[i] = i;
1da177e4 LT	40
cfa2b54e	41	for (i = 0; i < 256; i++) {
d366db60	42	u32 a = ctx->S[i];
1da177e4 LT	43	j = (j + in_key[k] + a) & 0xff;
	44	ctx->S[i] = ctx->S[j];
	45	ctx->S[j] = a;
cfa2b54e	46	if (++k >= key_len)
1da177e4 LT	47	k = 0;
	48	}
	49
	50	return 0;
	51	}
	52
ce6dd368 JK	53	static void arc4_crypt(struct arc4_ctx ctx, u8 out, const u8 *in,
ce6dd368 JK	54	unsigned int len)
1da177e4	55	{
d366db60 JK	56	u32 *const S = ctx->S;
	57	u32 x, y, a, b;
	58	u32 ty, ta, tb;
ce6dd368 JK	59
	60	if (len == 0)
	61	return;
	62
	63	x = ctx->x;
	64	y = ctx->y;
1da177e4 LT	65
	66	a = S[x];
	67	y = (y + a) & 0xff;
	68	b = S[y];
ce6dd368 JK	69
	70	do {
	71	S[y] = a;
	72	a = (a + b) & 0xff;
	73	S[x] = b;
	74	x = (x + 1) & 0xff;
	75	ta = S[x];
	76	ty = (y + ta) & 0xff;
	77	tb = S[ty];
	78	out++ = in++ ^ S[a];
	79	if (--len == 0)
	80	break;
	81	y = ty;
	82	a = ta;
	83	b = tb;
	84	} while (true);
1da177e4 LT	85
	86	ctx->x = x;
	87	ctx->y = y;
	88	}
	89
ce6dd368 JK	90	static void arc4_crypt_one(struct crypto_tfm tfm, u8 out, const u8 *in)
	91	{
	92	arc4_crypt(crypto_tfm_ctx(tfm), out, in, 1);
	93	}
	94
	95	static int ecb_arc4_crypt(struct blkcipher_desc desc, struct scatterlist dst,
	96	struct scatterlist *src, unsigned int nbytes)
	97	{
	98	struct arc4_ctx *ctx = crypto_blkcipher_ctx(desc->tfm);
	99	struct blkcipher_walk walk;
	100	int err;
	101
	102	blkcipher_walk_init(&walk, dst, src, nbytes);
	103
	104	err = blkcipher_walk_virt(desc, &walk);
	105
	106	while (walk.nbytes > 0) {
	107	u8 *wsrc = walk.src.virt.addr;
	108	u8 *wdst = walk.dst.virt.addr;
	109
	110	arc4_crypt(ctx, wdst, wsrc, walk.nbytes);
	111
	112	err = blkcipher_walk_done(desc, &walk, 0);
	113	}
	114
	115	return err;
	116	}
	117
	118	static struct crypto_alg arc4_algs[2] = { {
1da177e4 LT	119	.cra_name = "arc4",
	120	.cra_flags = CRYPTO_ALG_TYPE_CIPHER,
	121	.cra_blocksize = ARC4_BLOCK_SIZE,
	122	.cra_ctxsize = sizeof(struct arc4_ctx),
	123	.cra_module = THIS_MODULE,
ce6dd368 JK	124	.cra_u = {
	125	.cipher = {
	126	.cia_min_keysize = ARC4_MIN_KEY_SIZE,
	127	.cia_max_keysize = ARC4_MAX_KEY_SIZE,
	128	.cia_setkey = arc4_set_key,
	129	.cia_encrypt = arc4_crypt_one,
	130	.cia_decrypt = arc4_crypt_one,
	131	},
	132	},
	133	}, {
	134	.cra_name = "ecb(arc4)",
	135	.cra_priority = 100,
	136	.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER,
	137	.cra_blocksize = ARC4_BLOCK_SIZE,
	138	.cra_ctxsize = sizeof(struct arc4_ctx),
	139	.cra_alignmask = 0,
	140	.cra_type = &crypto_blkcipher_type,
	141	.cra_module = THIS_MODULE,
	142	.cra_u = {
	143	.blkcipher = {
	144	.min_keysize = ARC4_MIN_KEY_SIZE,
	145	.max_keysize = ARC4_MAX_KEY_SIZE,
	146	.setkey = arc4_set_key,
	147	.encrypt = ecb_arc4_crypt,
	148	.decrypt = ecb_arc4_crypt,
	149	},
	150	},
	151	} };
1da177e4 LT	152
	153	static int __init arc4_init(void)
	154	{
ce6dd368	155	return crypto_register_algs(arc4_algs, ARRAY_SIZE(arc4_algs));
1da177e4 LT	156	}
1da177e4 LT	157
1da177e4 LT	158	static void __exit arc4_exit(void)
1da177e4 LT	159	{
ce6dd368	160	crypto_unregister_algs(arc4_algs, ARRAY_SIZE(arc4_algs));
1da177e4 LT	161	}
	162
	163	module_init(arc4_init);
	164	module_exit(arc4_exit);
	165
	166	MODULE_LICENSE("GPL");
	167	MODULE_DESCRIPTION("ARC4 Cipher Algorithm");
	168	MODULE_AUTHOR("Jon Oberheide <jon@oberheide.org>");
5d26a105	169	MODULE_ALIAS_CRYPTO("arc4");