[mirror_ubuntu-focal-kernel.git] / crypto / chacha20_generic.c

/*
 * ChaCha20 256-bit cipher algorithm, RFC7539
 *
 * Copyright (C) 2015 Martin Willi
 *
 * 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 <crypto/algapi.h>
#include <crypto/chacha20.h>
#include <crypto/internal/skcipher.h>
#include <linux/module.h>

static inline u32 le32_to_cpuvp(const void *p)
{
	return le32_to_cpup(p);
}

static void chacha20_docrypt(u32 *state, u8 *dst, const u8 *src,
			     unsigned int bytes)
{
	u8 stream[CHACHA20_BLOCK_SIZE];

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

	while (bytes >= CHACHA20_BLOCK_SIZE) {
		chacha20_block(state, stream);
		crypto_xor(dst, stream, CHACHA20_BLOCK_SIZE);
		bytes -= CHACHA20_BLOCK_SIZE;
		dst += CHACHA20_BLOCK_SIZE;
	}
	if (bytes) {
		chacha20_block(state, stream);
		crypto_xor(dst, stream, bytes);
	}
}

void crypto_chacha20_init(u32 *state, struct chacha20_ctx *ctx, u8 *iv)
{
	state[0]  = 0x61707865; /* "expa" */
	state[1]  = 0x3320646e; /* "nd 3" */
	state[2]  = 0x79622d32; /* "2-by" */
	state[3]  = 0x6b206574; /* "te k" */
	state[4]  = ctx->key[0];
	state[5]  = ctx->key[1];
	state[6]  = ctx->key[2];
	state[7]  = ctx->key[3];
	state[8]  = ctx->key[4];
	state[9]  = ctx->key[5];
	state[10] = ctx->key[6];
	state[11] = ctx->key[7];
	state[12] = le32_to_cpuvp(iv +  0);
	state[13] = le32_to_cpuvp(iv +  4);
	state[14] = le32_to_cpuvp(iv +  8);
	state[15] = le32_to_cpuvp(iv + 12);
}
EXPORT_SYMBOL_GPL(crypto_chacha20_init);

int crypto_chacha20_setkey(struct crypto_skcipher *tfm, const u8 *key,
			   unsigned int keysize)
{
	struct chacha20_ctx *ctx = crypto_skcipher_ctx(tfm);
	int i;

	if (keysize != CHACHA20_KEY_SIZE)
		return -EINVAL;

	for (i = 0; i < ARRAY_SIZE(ctx->key); i++)
		ctx->key[i] = le32_to_cpuvp(key + i * sizeof(u32));

	return 0;
}
EXPORT_SYMBOL_GPL(crypto_chacha20_setkey);

int crypto_chacha20_crypt(struct skcipher_request *req)
{
	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
	struct chacha20_ctx *ctx = crypto_skcipher_ctx(tfm);
	struct skcipher_walk walk;
	u32 state[16];
	int err;

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

	crypto_chacha20_init(state, ctx, walk.iv);

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

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

		chacha20_docrypt(state, walk.dst.virt.addr, walk.src.virt.addr,
				 nbytes);
		err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
	}

	return err;
}
EXPORT_SYMBOL_GPL(crypto_chacha20_crypt);

static struct skcipher_alg alg = {
	.base.cra_name		= "chacha20",
	.base.cra_driver_name	= "chacha20-generic",
	.base.cra_priority	= 100,
	.base.cra_blocksize	= 1,
	.base.cra_ctxsize	= sizeof(struct chacha20_ctx),
	.base.cra_alignmask	= sizeof(u32) - 1,
	.base.cra_module	= THIS_MODULE,

	.min_keysize		= CHACHA20_KEY_SIZE,
	.max_keysize		= CHACHA20_KEY_SIZE,
	.ivsize			= CHACHA20_IV_SIZE,
	.chunksize		= CHACHA20_BLOCK_SIZE,
	.setkey			= crypto_chacha20_setkey,
	.encrypt		= crypto_chacha20_crypt,
	.decrypt		= crypto_chacha20_crypt,
};

static int __init chacha20_generic_mod_init(void)
{
	return crypto_register_skcipher(&alg);
}

static void __exit chacha20_generic_mod_fini(void)
{
	crypto_unregister_skcipher(&alg);
}

module_init(chacha20_generic_mod_init);
module_exit(chacha20_generic_mod_fini);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Martin Willi <martin@strongswan.org>");
MODULE_DESCRIPTION("chacha20 cipher algorithm");
MODULE_ALIAS_CRYPTO("chacha20");
MODULE_ALIAS_CRYPTO("chacha20-generic");
Commit	Line	Data
c08d0e64 MW	1	/*
	2	* ChaCha20 256-bit cipher algorithm, RFC7539
	3	*
	4	* Copyright (C) 2015 Martin Willi
	5	*
	6	* This program is free software; you can redistribute it and/or modify
	7	* it under the terms of the GNU General Public License as published by
	8	* the Free Software Foundation; either version 2 of the License, or
	9	* (at your option) any later version.
	10	*/
	11
	12	#include <crypto/algapi.h>
31d7247d	13	#include <crypto/chacha20.h>
9ae433bc AB	14	#include <crypto/internal/skcipher.h>
9ae433bc AB	15	#include <linux/module.h>
c08d0e64	16
c08d0e64 MW	17	static inline u32 le32_to_cpuvp(const void *p)
	18	{
	19	return le32_to_cpup(p);
	20	}
	21
c08d0e64 MW	22	static void chacha20_docrypt(u32 state, u8 dst, const u8 *src,
	23	unsigned int bytes)
	24	{
	25	u8 stream[CHACHA20_BLOCK_SIZE];
	26
	27	if (dst != src)
	28	memcpy(dst, src, bytes);
	29
	30	while (bytes >= CHACHA20_BLOCK_SIZE) {
	31	chacha20_block(state, stream);
	32	crypto_xor(dst, stream, CHACHA20_BLOCK_SIZE);
	33	bytes -= CHACHA20_BLOCK_SIZE;
	34	dst += CHACHA20_BLOCK_SIZE;
	35	}
	36	if (bytes) {
	37	chacha20_block(state, stream);
	38	crypto_xor(dst, stream, bytes);
	39	}
	40	}
	41
31d7247d	42	void crypto_chacha20_init(u32 state, struct chacha20_ctx ctx, u8 *iv)
c08d0e64	43	{
ecf3220d EB	44	state[0] = 0x61707865; /* "expa" */
	45	state[1] = 0x3320646e; /* "nd 3" */
	46	state[2] = 0x79622d32; /* "2-by" */
	47	state[3] = 0x6b206574; /* "te k" */
c08d0e64 MW	48	state[4] = ctx->key[0];
	49	state[5] = ctx->key[1];
	50	state[6] = ctx->key[2];
	51	state[7] = ctx->key[3];
	52	state[8] = ctx->key[4];
	53	state[9] = ctx->key[5];
	54	state[10] = ctx->key[6];
	55	state[11] = ctx->key[7];
	56	state[12] = le32_to_cpuvp(iv + 0);
	57	state[13] = le32_to_cpuvp(iv + 4);
	58	state[14] = le32_to_cpuvp(iv + 8);
	59	state[15] = le32_to_cpuvp(iv + 12);
	60	}
31d7247d	61	EXPORT_SYMBOL_GPL(crypto_chacha20_init);
c08d0e64	62
9ae433bc	63	int crypto_chacha20_setkey(struct crypto_skcipher tfm, const u8 key,
c08d0e64 MW	64	unsigned int keysize)
c08d0e64 MW	65	{
9ae433bc	66	struct chacha20_ctx *ctx = crypto_skcipher_ctx(tfm);
c08d0e64 MW	67	int i;
	68
	69	if (keysize != CHACHA20_KEY_SIZE)
	70	return -EINVAL;
	71
	72	for (i = 0; i < ARRAY_SIZE(ctx->key); i++)
	73	ctx->key[i] = le32_to_cpuvp(key + i * sizeof(u32));
	74
	75	return 0;
	76	}
31d7247d	77	EXPORT_SYMBOL_GPL(crypto_chacha20_setkey);
c08d0e64	78
9ae433bc	79	int crypto_chacha20_crypt(struct skcipher_request *req)
c08d0e64	80	{
9ae433bc AB	81	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
	82	struct chacha20_ctx *ctx = crypto_skcipher_ctx(tfm);
	83	struct skcipher_walk walk;
c08d0e64 MW	84	u32 state[16];
	85	int err;
	86
9ae433bc	87	err = skcipher_walk_virt(&walk, req, true);
c08d0e64	88
9ae433bc	89	crypto_chacha20_init(state, ctx, walk.iv);
c08d0e64	90
9ae433bc	91	while (walk.nbytes > 0) {
4de43726 AB	92	unsigned int nbytes = walk.nbytes;
	93
	94	if (nbytes < walk.total)
	95	nbytes = round_down(nbytes, walk.stride);
	96
c08d0e64	97	chacha20_docrypt(state, walk.dst.virt.addr, walk.src.virt.addr,
4de43726 AB	98	nbytes);
4de43726 AB	99	err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
c08d0e64 MW	100	}
	101
	102	return err;
	103	}
31d7247d	104	EXPORT_SYMBOL_GPL(crypto_chacha20_crypt);
c08d0e64	105
9ae433bc AB	106	static struct skcipher_alg alg = {
	107	.base.cra_name = "chacha20",
	108	.base.cra_driver_name = "chacha20-generic",
	109	.base.cra_priority = 100,
	110	.base.cra_blocksize = 1,
	111	.base.cra_ctxsize = sizeof(struct chacha20_ctx),
	112	.base.cra_alignmask = sizeof(u32) - 1,
	113	.base.cra_module = THIS_MODULE,
	114
	115	.min_keysize = CHACHA20_KEY_SIZE,
	116	.max_keysize = CHACHA20_KEY_SIZE,
	117	.ivsize = CHACHA20_IV_SIZE,
	118	.chunksize = CHACHA20_BLOCK_SIZE,
	119	.setkey = crypto_chacha20_setkey,
	120	.encrypt = crypto_chacha20_crypt,
	121	.decrypt = crypto_chacha20_crypt,
c08d0e64 MW	122	};
	123
	124	static int __init chacha20_generic_mod_init(void)
	125	{
9ae433bc	126	return crypto_register_skcipher(&alg);
c08d0e64 MW	127	}
	128
	129	static void __exit chacha20_generic_mod_fini(void)
	130	{
9ae433bc	131	crypto_unregister_skcipher(&alg);
c08d0e64 MW	132	}
	133
	134	module_init(chacha20_generic_mod_init);
	135	module_exit(chacha20_generic_mod_fini);
	136
	137	MODULE_LICENSE("GPL");
	138	MODULE_AUTHOR("Martin Willi <martin@strongswan.org>");
	139	MODULE_DESCRIPTION("chacha20 cipher algorithm");
	140	MODULE_ALIAS_CRYPTO("chacha20");
	141	MODULE_ALIAS_CRYPTO("chacha20-generic");