/* * 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>");