[linux.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 <linux/crypto.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <crypto/chacha20.h>

static inline u32 rotl32(u32 v, u8 n)
{
	return (v << n) | (v >> (sizeof(v) * 8 - n));
}

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

static void chacha20_block(u32 *state, void *stream)
{
	u32 x[16], *out = stream;
	int i;

	for (i = 0; i < ARRAY_SIZE(x); i++)
		x[i] = state[i];

	for (i = 0; i < 20; i += 2) {
		x[0]  += x[4];    x[12] = rotl32(x[12] ^ x[0],  16);
		x[1]  += x[5];    x[13] = rotl32(x[13] ^ x[1],  16);
		x[2]  += x[6];    x[14] = rotl32(x[14] ^ x[2],  16);
		x[3]  += x[7];    x[15] = rotl32(x[15] ^ x[3],  16);

		x[8]  += x[12];   x[4]  = rotl32(x[4]  ^ x[8],  12);
		x[9]  += x[13];   x[5]  = rotl32(x[5]  ^ x[9],  12);
		x[10] += x[14];   x[6]  = rotl32(x[6]  ^ x[10], 12);
		x[11] += x[15];   x[7]  = rotl32(x[7]  ^ x[11], 12);

		x[0]  += x[4];    x[12] = rotl32(x[12] ^ x[0],   8);
		x[1]  += x[5];    x[13] = rotl32(x[13] ^ x[1],   8);
		x[2]  += x[6];    x[14] = rotl32(x[14] ^ x[2],   8);
		x[3]  += x[7];    x[15] = rotl32(x[15] ^ x[3],   8);

		x[8]  += x[12];   x[4]  = rotl32(x[4]  ^ x[8],   7);
		x[9]  += x[13];   x[5]  = rotl32(x[5]  ^ x[9],   7);
		x[10] += x[14];   x[6]  = rotl32(x[6]  ^ x[10],  7);
		x[11] += x[15];   x[7]  = rotl32(x[7]  ^ x[11],  7);

		x[0]  += x[5];    x[15] = rotl32(x[15] ^ x[0],  16);
		x[1]  += x[6];    x[12] = rotl32(x[12] ^ x[1],  16);
		x[2]  += x[7];    x[13] = rotl32(x[13] ^ x[2],  16);
		x[3]  += x[4];    x[14] = rotl32(x[14] ^ x[3],  16);

		x[10] += x[15];   x[5]  = rotl32(x[5]  ^ x[10], 12);
		x[11] += x[12];   x[6]  = rotl32(x[6]  ^ x[11], 12);
		x[8]  += x[13];   x[7]  = rotl32(x[7]  ^ x[8],  12);
		x[9]  += x[14];   x[4]  = rotl32(x[4]  ^ x[9],  12);

		x[0]  += x[5];    x[15] = rotl32(x[15] ^ x[0],   8);
		x[1]  += x[6];    x[12] = rotl32(x[12] ^ x[1],   8);
		x[2]  += x[7];    x[13] = rotl32(x[13] ^ x[2],   8);
		x[3]  += x[4];    x[14] = rotl32(x[14] ^ x[3],   8);

		x[10] += x[15];   x[5]  = rotl32(x[5]  ^ x[10],  7);
		x[11] += x[12];   x[6]  = rotl32(x[6]  ^ x[11],  7);
		x[8]  += x[13];   x[7]  = rotl32(x[7]  ^ x[8],   7);
		x[9]  += x[14];   x[4]  = rotl32(x[4]  ^ x[9],   7);
	}

	for (i = 0; i < ARRAY_SIZE(x); i++)
		out[i] = cpu_to_le32(x[i] + state[i]);

	state[12]++;
}

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)
{
	static const char constant[16] = "expand 32-byte k";

	state[0]  = le32_to_cpuvp(constant +  0);
	state[1]  = le32_to_cpuvp(constant +  4);
	state[2]  = le32_to_cpuvp(constant +  8);
	state[3]  = le32_to_cpuvp(constant + 12);
	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_tfm *tfm, const u8 *key,
			   unsigned int keysize)
{
	struct chacha20_ctx *ctx = crypto_tfm_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 blkcipher_desc *desc, struct scatterlist *dst,
			  struct scatterlist *src, unsigned int nbytes)
{
	struct blkcipher_walk walk;
	u32 state[16];
	int err;

	blkcipher_walk_init(&walk, dst, src, nbytes);
	err = blkcipher_walk_virt_block(desc, &walk, CHACHA20_BLOCK_SIZE);

	crypto_chacha20_init(state, crypto_blkcipher_ctx(desc->tfm), walk.iv);

	while (walk.nbytes >= CHACHA20_BLOCK_SIZE) {
		chacha20_docrypt(state, walk.dst.virt.addr, walk.src.virt.addr,
				 rounddown(walk.nbytes, CHACHA20_BLOCK_SIZE));
		err = blkcipher_walk_done(desc, &walk,
					  walk.nbytes % CHACHA20_BLOCK_SIZE);
	}

	if (walk.nbytes) {
		chacha20_docrypt(state, walk.dst.virt.addr, walk.src.virt.addr,
				 walk.nbytes);
		err = blkcipher_walk_done(desc, &walk, 0);
	}

	return err;
}
EXPORT_SYMBOL_GPL(crypto_chacha20_crypt);

static struct crypto_alg alg = {
	.cra_name		= "chacha20",
	.cra_driver_name	= "chacha20-generic",
	.cra_priority		= 100,
	.cra_flags		= CRYPTO_ALG_TYPE_BLKCIPHER,
	.cra_blocksize		= 1,
	.cra_type		= &crypto_blkcipher_type,
	.cra_ctxsize		= sizeof(struct chacha20_ctx),
	.cra_alignmask		= sizeof(u32) - 1,
	.cra_module		= THIS_MODULE,
	.cra_u			= {
		.blkcipher = {
			.min_keysize	= CHACHA20_KEY_SIZE,
			.max_keysize	= CHACHA20_KEY_SIZE,
			.ivsize		= CHACHA20_IV_SIZE,
			.geniv		= "seqiv",
			.setkey		= crypto_chacha20_setkey,
			.encrypt	= crypto_chacha20_crypt,
			.decrypt	= crypto_chacha20_crypt,
		},
	},
};

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

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

module_init(chacha20_generic_mod_init);
module_exit(chacha20_generic_mod_fini);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Martin Willi <[email protected]>");
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>
	13	#include <linux/crypto.h>
	14	#include <linux/kernel.h>
	15	#include <linux/module.h>
31d7247d	16	#include <crypto/chacha20.h>
c08d0e64 MW	17
	18	static inline u32 rotl32(u32 v, u8 n)
	19	{
	20	return (v << n) \| (v >> (sizeof(v) * 8 - n));
	21	}
	22
	23	static inline u32 le32_to_cpuvp(const void *p)
	24	{
	25	return le32_to_cpup(p);
	26	}
	27
	28	static void chacha20_block(u32 state, void stream)
	29	{
	30	u32 x[16], *out = stream;
	31	int i;
	32
	33	for (i = 0; i < ARRAY_SIZE(x); i++)
	34	x[i] = state[i];
	35
	36	for (i = 0; i < 20; i += 2) {
	37	x[0] += x[4]; x[12] = rotl32(x[12] ^ x[0], 16);
	38	x[1] += x[5]; x[13] = rotl32(x[13] ^ x[1], 16);
	39	x[2] += x[6]; x[14] = rotl32(x[14] ^ x[2], 16);
	40	x[3] += x[7]; x[15] = rotl32(x[15] ^ x[3], 16);
	41
	42	x[8] += x[12]; x[4] = rotl32(x[4] ^ x[8], 12);
	43	x[9] += x[13]; x[5] = rotl32(x[5] ^ x[9], 12);
	44	x[10] += x[14]; x[6] = rotl32(x[6] ^ x[10], 12);
	45	x[11] += x[15]; x[7] = rotl32(x[7] ^ x[11], 12);
	46
	47	x[0] += x[4]; x[12] = rotl32(x[12] ^ x[0], 8);
	48	x[1] += x[5]; x[13] = rotl32(x[13] ^ x[1], 8);
	49	x[2] += x[6]; x[14] = rotl32(x[14] ^ x[2], 8);
	50	x[3] += x[7]; x[15] = rotl32(x[15] ^ x[3], 8);
	51
	52	x[8] += x[12]; x[4] = rotl32(x[4] ^ x[8], 7);
	53	x[9] += x[13]; x[5] = rotl32(x[5] ^ x[9], 7);
	54	x[10] += x[14]; x[6] = rotl32(x[6] ^ x[10], 7);
	55	x[11] += x[15]; x[7] = rotl32(x[7] ^ x[11], 7);
	56
	57	x[0] += x[5]; x[15] = rotl32(x[15] ^ x[0], 16);
	58	x[1] += x[6]; x[12] = rotl32(x[12] ^ x[1], 16);
	59	x[2] += x[7]; x[13] = rotl32(x[13] ^ x[2], 16);
	60	x[3] += x[4]; x[14] = rotl32(x[14] ^ x[3], 16);
	61
	62	x[10] += x[15]; x[5] = rotl32(x[5] ^ x[10], 12);
	63	x[11] += x[12]; x[6] = rotl32(x[6] ^ x[11], 12);
	64	x[8] += x[13]; x[7] = rotl32(x[7] ^ x[8], 12);
	65	x[9] += x[14]; x[4] = rotl32(x[4] ^ x[9], 12);
	66
	67	x[0] += x[5]; x[15] = rotl32(x[15] ^ x[0], 8);
	68	x[1] += x[6]; x[12] = rotl32(x[12] ^ x[1], 8);
	69	x[2] += x[7]; x[13] = rotl32(x[13] ^ x[2], 8);
	70	x[3] += x[4]; x[14] = rotl32(x[14] ^ x[3], 8);
	71
	72	x[10] += x[15]; x[5] = rotl32(x[5] ^ x[10], 7);
	73	x[11] += x[12]; x[6] = rotl32(x[6] ^ x[11], 7);
	74	x[8] += x[13]; x[7] = rotl32(x[7] ^ x[8], 7);
	75	x[9] += x[14]; x[4] = rotl32(x[4] ^ x[9], 7);
	76	}
	77
	78	for (i = 0; i < ARRAY_SIZE(x); i++)
	79	out[i] = cpu_to_le32(x[i] + state[i]);
	80
81	state[12]++;
82	}
83
84	static void chacha20_docrypt(u32 state, u8 dst, const u8 *src,
85	unsigned int bytes)
86	{
87	u8 stream[CHACHA20_BLOCK_SIZE];
88
89	if (dst != src)
90	memcpy(dst, src, bytes);
91
92	while (bytes >= CHACHA20_BLOCK_SIZE) {
93	chacha20_block(state, stream);
94	crypto_xor(dst, stream, CHACHA20_BLOCK_SIZE);
95	bytes -= CHACHA20_BLOCK_SIZE;
96	dst += CHACHA20_BLOCK_SIZE;
97	}
98	if (bytes) {
99	chacha20_block(state, stream);
100	crypto_xor(dst, stream, bytes);
101	}
102	}
103
31d7247d	104	void crypto_chacha20_init(u32 state, struct chacha20_ctx ctx, u8 *iv)
c08d0e64 MW	105	{
	106	static const char constant[16] = "expand 32-byte k";
	107
	108	state[0] = le32_to_cpuvp(constant + 0);
	109	state[1] = le32_to_cpuvp(constant + 4);
	110	state[2] = le32_to_cpuvp(constant + 8);
	111	state[3] = le32_to_cpuvp(constant + 12);
	112	state[4] = ctx->key[0];
	113	state[5] = ctx->key[1];
	114	state[6] = ctx->key[2];
	115	state[7] = ctx->key[3];
	116	state[8] = ctx->key[4];
	117	state[9] = ctx->key[5];
	118	state[10] = ctx->key[6];
	119	state[11] = ctx->key[7];
	120	state[12] = le32_to_cpuvp(iv + 0);
	121	state[13] = le32_to_cpuvp(iv + 4);
	122	state[14] = le32_to_cpuvp(iv + 8);
	123	state[15] = le32_to_cpuvp(iv + 12);
	124	}
31d7247d	125	EXPORT_SYMBOL_GPL(crypto_chacha20_init);
c08d0e64	126
31d7247d	127	int crypto_chacha20_setkey(struct crypto_tfm tfm, const u8 key,
c08d0e64 MW	128	unsigned int keysize)
	129	{
	130	struct chacha20_ctx *ctx = crypto_tfm_ctx(tfm);
	131	int i;
	132
	133	if (keysize != CHACHA20_KEY_SIZE)
	134	return -EINVAL;
	135
	136	for (i = 0; i < ARRAY_SIZE(ctx->key); i++)
	137	ctx->key[i] = le32_to_cpuvp(key + i * sizeof(u32));
	138
	139	return 0;
	140	}
31d7247d	141	EXPORT_SYMBOL_GPL(crypto_chacha20_setkey);
c08d0e64	142
31d7247d	143	int crypto_chacha20_crypt(struct blkcipher_desc desc, struct scatterlist dst,
c08d0e64 MW	144	struct scatterlist *src, unsigned int nbytes)
	145	{
	146	struct blkcipher_walk walk;
	147	u32 state[16];
	148	int err;
	149
	150	blkcipher_walk_init(&walk, dst, src, nbytes);
	151	err = blkcipher_walk_virt_block(desc, &walk, CHACHA20_BLOCK_SIZE);
	152
31d7247d	153	crypto_chacha20_init(state, crypto_blkcipher_ctx(desc->tfm), walk.iv);
c08d0e64 MW	154
	155	while (walk.nbytes >= CHACHA20_BLOCK_SIZE) {
	156	chacha20_docrypt(state, walk.dst.virt.addr, walk.src.virt.addr,
	157	rounddown(walk.nbytes, CHACHA20_BLOCK_SIZE));
	158	err = blkcipher_walk_done(desc, &walk,
	159	walk.nbytes % CHACHA20_BLOCK_SIZE);
	160	}
	161
	162	if (walk.nbytes) {
	163	chacha20_docrypt(state, walk.dst.virt.addr, walk.src.virt.addr,
	164	walk.nbytes);
	165	err = blkcipher_walk_done(desc, &walk, 0);
	166	}
	167
	168	return err;
	169	}
31d7247d	170	EXPORT_SYMBOL_GPL(crypto_chacha20_crypt);
c08d0e64 MW	171
	172	static struct crypto_alg alg = {
	173	.cra_name = "chacha20",
	174	.cra_driver_name = "chacha20-generic",
	175	.cra_priority = 100,
	176	.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER,
	177	.cra_blocksize = 1,
	178	.cra_type = &crypto_blkcipher_type,
	179	.cra_ctxsize = sizeof(struct chacha20_ctx),
	180	.cra_alignmask = sizeof(u32) - 1,
	181	.cra_module = THIS_MODULE,
	182	.cra_u = {
	183	.blkcipher = {
	184	.min_keysize = CHACHA20_KEY_SIZE,
	185	.max_keysize = CHACHA20_KEY_SIZE,
31d7247d	186	.ivsize = CHACHA20_IV_SIZE,
c08d0e64	187	.geniv = "seqiv",
31d7247d MW	188	.setkey = crypto_chacha20_setkey,
	189	.encrypt = crypto_chacha20_crypt,
	190	.decrypt = crypto_chacha20_crypt,
c08d0e64 MW	191	},
	192	},
	193	};
	194
	195	static int __init chacha20_generic_mod_init(void)
	196	{
	197	return crypto_register_alg(&alg);
	198	}
	199
	200	static void __exit chacha20_generic_mod_fini(void)
	201	{
	202	crypto_unregister_alg(&alg);
	203	}
	204
	205	module_init(chacha20_generic_mod_init);
	206	module_exit(chacha20_generic_mod_fini);
	207
	208	MODULE_LICENSE("GPL");
	209	MODULE_AUTHOR("Martin Willi <[email protected]>");
	210	MODULE_DESCRIPTION("chacha20 cipher algorithm");
	211	MODULE_ALIAS_CRYPTO("chacha20");
	212	MODULE_ALIAS_CRYPTO("chacha20-generic");