[deliverable/linux.git] / crypto / crc32c.c

/* 
 * Cryptographic API.
 *
 * CRC32C chksum
 *
 * This module file is a wrapper to invoke the lib/crc32c routines.
 *
 * 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/init.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/crypto.h>
#include <linux/crc32c.h>
#include <linux/kernel.h>

#define CHKSUM_BLOCK_SIZE	32
#define CHKSUM_DIGEST_SIZE	4

struct chksum_ctx {
	u32 crc;
	u32 key;
};

/*
 * Steps through buffer one byte at at time, calculates reflected 
 * crc using table.
 */

static void chksum_init(struct crypto_tfm *tfm)
{
	struct chksum_ctx *mctx = crypto_tfm_ctx(tfm);

	mctx->crc = mctx->key;
}

/*
 * Setting the seed allows arbitrary accumulators and flexible XOR policy
 * If your algorithm starts with ~0, then XOR with ~0 before you set
 * the seed.
 */
static int chksum_setkey(struct crypto_tfm *tfm, const u8 *key,
			 unsigned int keylen)
{
	struct chksum_ctx *mctx = crypto_tfm_ctx(tfm);

	if (keylen != sizeof(mctx->crc)) {
		tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
		return -EINVAL;
	}
	mctx->key = le32_to_cpu(*(__le32 *)key);
	return 0;
}

static void chksum_update(struct crypto_tfm *tfm, const u8 *data,
			  unsigned int length)
{
	struct chksum_ctx *mctx = crypto_tfm_ctx(tfm);

	mctx->crc = crc32c(mctx->crc, data, length);
}

static void chksum_final(struct crypto_tfm *tfm, u8 *out)
{
	struct chksum_ctx *mctx = crypto_tfm_ctx(tfm);
	
	*(__le32 *)out = ~cpu_to_le32(mctx->crc);
}

static int crc32c_cra_init(struct crypto_tfm *tfm)
{
	struct chksum_ctx *mctx = crypto_tfm_ctx(tfm);

	mctx->key = ~0;
	return 0;
}

static struct crypto_alg alg = {
	.cra_name	=	"crc32c",
	.cra_flags	=	CRYPTO_ALG_TYPE_DIGEST,
	.cra_blocksize	=	CHKSUM_BLOCK_SIZE,
	.cra_ctxsize	=	sizeof(struct chksum_ctx),
	.cra_module	=	THIS_MODULE,
	.cra_list	=	LIST_HEAD_INIT(alg.cra_list),
	.cra_init	=	crc32c_cra_init,
	.cra_u		=	{
		.digest = {
			 .dia_digestsize=	CHKSUM_DIGEST_SIZE,
			 .dia_setkey	=	chksum_setkey,
			 .dia_init   	= 	chksum_init,
			 .dia_update 	=	chksum_update,
			 .dia_final  	=	chksum_final
		 }
	}
};

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

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

module_init(init);
module_exit(fini);

MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>");
MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations wrapper for lib/crc32c");
MODULE_LICENSE("GPL");
Commit	Line	Data
	1	/*
	2	* Cryptographic API.
	3	*
	4	* CRC32C chksum
	5	*
	6	* This module file is a wrapper to invoke the lib/crc32c routines.
	7	*
	8	* This program is free software; you can redistribute it and/or modify it
	9	* under the terms of the GNU General Public License as published by the Free
	10	* Software Foundation; either version 2 of the License, or (at your option)
	11	* any later version.
	12	*
	13	*/
	14	#include <linux/init.h>
	15	#include <linux/module.h>
	16	#include <linux/string.h>
	17	#include <linux/crypto.h>
	18	#include <linux/crc32c.h>
	19	#include <linux/kernel.h>
	20
	21	#define CHKSUM_BLOCK_SIZE 32
	22	#define CHKSUM_DIGEST_SIZE 4
	23
	24	struct chksum_ctx {
	25	u32 crc;
	26	u32 key;
	27	};
	28
	29	/*
	30	* Steps through buffer one byte at at time, calculates reflected
	31	* crc using table.
	32	*/
	33
	34	static void chksum_init(struct crypto_tfm *tfm)
	35	{
	36	struct chksum_ctx *mctx = crypto_tfm_ctx(tfm);
	37
	38	mctx->crc = mctx->key;
	39	}
	40
	41	/*
	42	* Setting the seed allows arbitrary accumulators and flexible XOR policy
	43	* If your algorithm starts with ~0, then XOR with ~0 before you set
	44	* the seed.
	45	*/
	46	static int chksum_setkey(struct crypto_tfm tfm, const u8 key,
	47	unsigned int keylen)
	48	{
	49	struct chksum_ctx *mctx = crypto_tfm_ctx(tfm);
	50
	51	if (keylen != sizeof(mctx->crc)) {
	52	tfm->crt_flags \|= CRYPTO_TFM_RES_BAD_KEY_LEN;
	53	return -EINVAL;
	54	}
	55	mctx->key = le32_to_cpu((__le32 )key);
	56	return 0;
	57	}
	58
	59	static void chksum_update(struct crypto_tfm tfm, const u8 data,
	60	unsigned int length)
	61	{
	62	struct chksum_ctx *mctx = crypto_tfm_ctx(tfm);
	63
	64	mctx->crc = crc32c(mctx->crc, data, length);
	65	}
	66
	67	static void chksum_final(struct crypto_tfm tfm, u8 out)
	68	{
	69	struct chksum_ctx *mctx = crypto_tfm_ctx(tfm);
	70
	71	(__le32 )out = ~cpu_to_le32(mctx->crc);
	72	}
	73
	74	static int crc32c_cra_init(struct crypto_tfm *tfm)
	75	{
	76	struct chksum_ctx *mctx = crypto_tfm_ctx(tfm);
	77
	78	mctx->key = ~0;
	79	return 0;
	80	}
	81
	82	static struct crypto_alg alg = {
	83	.cra_name = "crc32c",
	84	.cra_flags = CRYPTO_ALG_TYPE_DIGEST,
	85	.cra_blocksize = CHKSUM_BLOCK_SIZE,
	86	.cra_ctxsize = sizeof(struct chksum_ctx),
	87	.cra_module = THIS_MODULE,
	88	.cra_list = LIST_HEAD_INIT(alg.cra_list),
	89	.cra_init = crc32c_cra_init,
	90	.cra_u = {
	91	.digest = {
	92	.dia_digestsize= CHKSUM_DIGEST_SIZE,
	93	.dia_setkey = chksum_setkey,
	94	.dia_init = chksum_init,
	95	.dia_update = chksum_update,
	96	.dia_final = chksum_final
	97	}
	98	}
	99	};
	100
	101	static int __init init(void)
	102	{
	103	return crypto_register_alg(&alg);
	104	}
	105
	106	static void __exit fini(void)
	107	{
	108	crypto_unregister_alg(&alg);
	109	}
	110
	111	module_init(init);
	112	module_exit(fini);
	113
	114	MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>");
	115	MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations wrapper for lib/crc32c");
	116	MODULE_LICENSE("GPL");