[linux.git] / crypto / nhpoly1305.c

// SPDX-License-Identifier: GPL-2.0
/*
 * NHPoly1305 - ε-almost-∆-universal hash function for Adiantum
 *
 * Copyright 2018 Google LLC
 */

/*
 * "NHPoly1305" is the main component of Adiantum hashing.
 * Specifically, it is the calculation
 *
 *	H_L ← Poly1305_{K_L}(NH_{K_N}(pad_{128}(L)))
 *
 * from the procedure in section 6.4 of the Adiantum paper [1].  It is an
 * ε-almost-∆-universal (ε-∆U) hash function for equal-length inputs over
 * Z/(2^{128}Z), where the "∆" operation is addition.  It hashes 1024-byte
 * chunks of the input with the NH hash function [2], reducing the input length
 * by 32x.  The resulting NH digests are evaluated as a polynomial in
 * GF(2^{130}-5), like in the Poly1305 MAC [3].  Note that the polynomial
 * evaluation by itself would suffice to achieve the ε-∆U property; NH is used
 * for performance since it's over twice as fast as Poly1305.
 *
 * This is *not* a cryptographic hash function; do not use it as such!
 *
 * [1] Adiantum: length-preserving encryption for entry-level processors
 *     (https://eprint.iacr.org/2018/720.pdf)
 * [2] UMAC: Fast and Secure Message Authentication
 *     (https://fastcrypto.org/umac/umac_proc.pdf)
 * [3] The Poly1305-AES message-authentication code
 *     (https://cr.yp.to/mac/poly1305-20050329.pdf)
 */

#include <asm/unaligned.h>
#include <crypto/algapi.h>
#include <crypto/internal/hash.h>
#include <crypto/internal/poly1305.h>
#include <crypto/nhpoly1305.h>
#include <linux/crypto.h>
#include <linux/kernel.h>
#include <linux/module.h>

static void nh_generic(const u32 *key, const u8 *message, size_t message_len,
		       __le64 hash[NH_NUM_PASSES])
{
	u64 sums[4] = { 0, 0, 0, 0 };

	BUILD_BUG_ON(NH_PAIR_STRIDE != 2);
	BUILD_BUG_ON(NH_NUM_PASSES != 4);

	while (message_len) {
		u32 m0 = get_unaligned_le32(message + 0);
		u32 m1 = get_unaligned_le32(message + 4);
		u32 m2 = get_unaligned_le32(message + 8);
		u32 m3 = get_unaligned_le32(message + 12);

		sums[0] += (u64)(u32)(m0 + key[ 0]) * (u32)(m2 + key[ 2]);
		sums[1] += (u64)(u32)(m0 + key[ 4]) * (u32)(m2 + key[ 6]);
		sums[2] += (u64)(u32)(m0 + key[ 8]) * (u32)(m2 + key[10]);
		sums[3] += (u64)(u32)(m0 + key[12]) * (u32)(m2 + key[14]);
		sums[0] += (u64)(u32)(m1 + key[ 1]) * (u32)(m3 + key[ 3]);
		sums[1] += (u64)(u32)(m1 + key[ 5]) * (u32)(m3 + key[ 7]);
		sums[2] += (u64)(u32)(m1 + key[ 9]) * (u32)(m3 + key[11]);
		sums[3] += (u64)(u32)(m1 + key[13]) * (u32)(m3 + key[15]);
		key += NH_MESSAGE_UNIT / sizeof(key[0]);
		message += NH_MESSAGE_UNIT;
		message_len -= NH_MESSAGE_UNIT;
	}

	hash[0] = cpu_to_le64(sums[0]);
	hash[1] = cpu_to_le64(sums[1]);
	hash[2] = cpu_to_le64(sums[2]);
	hash[3] = cpu_to_le64(sums[3]);
}

/* Pass the next NH hash value through Poly1305 */
static void process_nh_hash_value(struct nhpoly1305_state *state,
				  const struct nhpoly1305_key *key)
{
	BUILD_BUG_ON(NH_HASH_BYTES % POLY1305_BLOCK_SIZE != 0);

	poly1305_core_blocks(&state->poly_state, &key->poly_key, state->nh_hash,
			     NH_HASH_BYTES / POLY1305_BLOCK_SIZE, 1);
}

/*
 * Feed the next portion of the source data, as a whole number of 16-byte
 * "NH message units", through NH and Poly1305.  Each NH hash is taken over
 * 1024 bytes, except possibly the final one which is taken over a multiple of
 * 16 bytes up to 1024.  Also, in the case where data is passed in misaligned
 * chunks, we combine partial hashes; the end result is the same either way.
 */
static void nhpoly1305_units(struct nhpoly1305_state *state,
			     const struct nhpoly1305_key *key,
			     const u8 *src, unsigned int srclen, nh_t nh_fn)
{
	do {
		unsigned int bytes;

		if (state->nh_remaining == 0) {
			/* Starting a new NH message */
			bytes = min_t(unsigned int, srclen, NH_MESSAGE_BYTES);
			nh_fn(key->nh_key, src, bytes, state->nh_hash);
			state->nh_remaining = NH_MESSAGE_BYTES - bytes;
		} else {
			/* Continuing a previous NH message */
			__le64 tmp_hash[NH_NUM_PASSES];
			unsigned int pos;
			int i;

			pos = NH_MESSAGE_BYTES - state->nh_remaining;
			bytes = min(srclen, state->nh_remaining);
			nh_fn(&key->nh_key[pos / 4], src, bytes, tmp_hash);
			for (i = 0; i < NH_NUM_PASSES; i++)
				le64_add_cpu(&state->nh_hash[i],
					     le64_to_cpu(tmp_hash[i]));
			state->nh_remaining -= bytes;
		}
		if (state->nh_remaining == 0)
			process_nh_hash_value(state, key);
		src += bytes;
		srclen -= bytes;
	} while (srclen);
}

int crypto_nhpoly1305_setkey(struct crypto_shash *tfm,
			     const u8 *key, unsigned int keylen)
{
	struct nhpoly1305_key *ctx = crypto_shash_ctx(tfm);
	int i;

	if (keylen != NHPOLY1305_KEY_SIZE)
		return -EINVAL;

	poly1305_core_setkey(&ctx->poly_key, key);
	key += POLY1305_BLOCK_SIZE;

	for (i = 0; i < NH_KEY_WORDS; i++)
		ctx->nh_key[i] = get_unaligned_le32(key + i * sizeof(u32));

	return 0;
}
EXPORT_SYMBOL(crypto_nhpoly1305_setkey);

int crypto_nhpoly1305_init(struct shash_desc *desc)
{
	struct nhpoly1305_state *state = shash_desc_ctx(desc);

	poly1305_core_init(&state->poly_state);
	state->buflen = 0;
	state->nh_remaining = 0;
	return 0;
}
EXPORT_SYMBOL(crypto_nhpoly1305_init);

int crypto_nhpoly1305_update_helper(struct shash_desc *desc,
				    const u8 *src, unsigned int srclen,
				    nh_t nh_fn)
{
	struct nhpoly1305_state *state = shash_desc_ctx(desc);
	const struct nhpoly1305_key *key = crypto_shash_ctx(desc->tfm);
	unsigned int bytes;

	if (state->buflen) {
		bytes = min(srclen, (int)NH_MESSAGE_UNIT - state->buflen);
		memcpy(&state->buffer[state->buflen], src, bytes);
		state->buflen += bytes;
		if (state->buflen < NH_MESSAGE_UNIT)
			return 0;
		nhpoly1305_units(state, key, state->buffer, NH_MESSAGE_UNIT,
				 nh_fn);
		state->buflen = 0;
		src += bytes;
		srclen -= bytes;
	}

	if (srclen >= NH_MESSAGE_UNIT) {
		bytes = round_down(srclen, NH_MESSAGE_UNIT);
		nhpoly1305_units(state, key, src, bytes, nh_fn);
		src += bytes;
		srclen -= bytes;
	}

	if (srclen) {
		memcpy(state->buffer, src, srclen);
		state->buflen = srclen;
	}
	return 0;
}
EXPORT_SYMBOL(crypto_nhpoly1305_update_helper);

int crypto_nhpoly1305_update(struct shash_desc *desc,
			     const u8 *src, unsigned int srclen)
{
	return crypto_nhpoly1305_update_helper(desc, src, srclen, nh_generic);
}
EXPORT_SYMBOL(crypto_nhpoly1305_update);

int crypto_nhpoly1305_final_helper(struct shash_desc *desc, u8 *dst, nh_t nh_fn)
{
	struct nhpoly1305_state *state = shash_desc_ctx(desc);
	const struct nhpoly1305_key *key = crypto_shash_ctx(desc->tfm);

	if (state->buflen) {
		memset(&state->buffer[state->buflen], 0,
		       NH_MESSAGE_UNIT - state->buflen);
		nhpoly1305_units(state, key, state->buffer, NH_MESSAGE_UNIT,
				 nh_fn);
	}

	if (state->nh_remaining)
		process_nh_hash_value(state, key);

	poly1305_core_emit(&state->poly_state, NULL, dst);
	return 0;
}
EXPORT_SYMBOL(crypto_nhpoly1305_final_helper);

int crypto_nhpoly1305_final(struct shash_desc *desc, u8 *dst)
{
	return crypto_nhpoly1305_final_helper(desc, dst, nh_generic);
}
EXPORT_SYMBOL(crypto_nhpoly1305_final);

static struct shash_alg nhpoly1305_alg = {
	.base.cra_name		= "nhpoly1305",
	.base.cra_driver_name	= "nhpoly1305-generic",
	.base.cra_priority	= 100,
	.base.cra_ctxsize	= sizeof(struct nhpoly1305_key),
	.base.cra_module	= THIS_MODULE,
	.digestsize		= POLY1305_DIGEST_SIZE,
	.init			= crypto_nhpoly1305_init,
	.update			= crypto_nhpoly1305_update,
	.final			= crypto_nhpoly1305_final,
	.setkey			= crypto_nhpoly1305_setkey,
	.descsize		= sizeof(struct nhpoly1305_state),
};

static int __init nhpoly1305_mod_init(void)
{
	return crypto_register_shash(&nhpoly1305_alg);
}

static void __exit nhpoly1305_mod_exit(void)
{
	crypto_unregister_shash(&nhpoly1305_alg);
}

subsys_initcall(nhpoly1305_mod_init);
module_exit(nhpoly1305_mod_exit);

MODULE_DESCRIPTION("NHPoly1305 ε-almost-∆-universal hash function");
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Eric Biggers <[email protected]>");
MODULE_ALIAS_CRYPTO("nhpoly1305");
MODULE_ALIAS_CRYPTO("nhpoly1305-generic");
Commit	Line	Data
26609a21 EB	1	// SPDX-License-Identifier: GPL-2.0
	2	/*
	3	* NHPoly1305 - ε-almost-∆-universal hash function for Adiantum
	4	*
	5	* Copyright 2018 Google LLC
	6	*/
	7
	8	/*
	9	* "NHPoly1305" is the main component of Adiantum hashing.
	10	* Specifically, it is the calculation
	11	*
c6018e1a	12	* H_L ← Poly1305_{K_L}(NH_{K_N}(pad_{128}(L)))
26609a21	13	*
c6018e1a EB	14	* from the procedure in section 6.4 of the Adiantum paper [1]. It is an
c6018e1a EB	15	* ε-almost-∆-universal (ε-∆U) hash function for equal-length inputs over
26609a21 EB	16	* Z/(2^{128}Z), where the "∆" operation is addition. It hashes 1024-byte
	17	* chunks of the input with the NH hash function [2], reducing the input length
	18	* by 32x. The resulting NH digests are evaluated as a polynomial in
	19	* GF(2^{130}-5), like in the Poly1305 MAC [3]. Note that the polynomial
c6018e1a	20	* evaluation by itself would suffice to achieve the ε-∆U property; NH is used
26609a21 EB	21	* for performance since it's over twice as fast as Poly1305.
	22	*
	23	* This is not a cryptographic hash function; do not use it as such!
	24	*
	25	* [1] Adiantum: length-preserving encryption for entry-level processors
	26	* (https://eprint.iacr.org/2018/720.pdf)
	27	* [2] UMAC: Fast and Secure Message Authentication
	28	* (https://fastcrypto.org/umac/umac_proc.pdf)
	29	* [3] The Poly1305-AES message-authentication code
	30	* (https://cr.yp.to/mac/poly1305-20050329.pdf)
	31	*/
	32
	33	#include <asm/unaligned.h>
	34	#include <crypto/algapi.h>
	35	#include <crypto/internal/hash.h>
48ea8c6e	36	#include <crypto/internal/poly1305.h>
26609a21 EB	37	#include <crypto/nhpoly1305.h>
	38	#include <linux/crypto.h>
	39	#include <linux/kernel.h>
	40	#include <linux/module.h>
	41
	42	static void nh_generic(const u32 key, const u8 message, size_t message_len,
	43	__le64 hash[NH_NUM_PASSES])
	44	{
	45	u64 sums[4] = { 0, 0, 0, 0 };
	46
	47	BUILD_BUG_ON(NH_PAIR_STRIDE != 2);
	48	BUILD_BUG_ON(NH_NUM_PASSES != 4);
	49
	50	while (message_len) {
	51	u32 m0 = get_unaligned_le32(message + 0);
	52	u32 m1 = get_unaligned_le32(message + 4);
	53	u32 m2 = get_unaligned_le32(message + 8);
	54	u32 m3 = get_unaligned_le32(message + 12);
	55
	56	sums[0] += (u64)(u32)(m0 + key[ 0]) * (u32)(m2 + key[ 2]);
	57	sums[1] += (u64)(u32)(m0 + key[ 4]) * (u32)(m2 + key[ 6]);
	58	sums[2] += (u64)(u32)(m0 + key[ 8]) * (u32)(m2 + key[10]);
	59	sums[3] += (u64)(u32)(m0 + key[12]) * (u32)(m2 + key[14]);
	60	sums[0] += (u64)(u32)(m1 + key[ 1]) * (u32)(m3 + key[ 3]);
	61	sums[1] += (u64)(u32)(m1 + key[ 5]) * (u32)(m3 + key[ 7]);
	62	sums[2] += (u64)(u32)(m1 + key[ 9]) * (u32)(m3 + key[11]);
	63	sums[3] += (u64)(u32)(m1 + key[13]) * (u32)(m3 + key[15]);
	64	key += NH_MESSAGE_UNIT / sizeof(key[0]);
	65	message += NH_MESSAGE_UNIT;
	66	message_len -= NH_MESSAGE_UNIT;
	67	}
	68
	69	hash[0] = cpu_to_le64(sums[0]);
	70	hash[1] = cpu_to_le64(sums[1]);
	71	hash[2] = cpu_to_le64(sums[2]);
	72	hash[3] = cpu_to_le64(sums[3]);
	73	}
	74
	75	/* Pass the next NH hash value through Poly1305 */
	76	static void process_nh_hash_value(struct nhpoly1305_state *state,
	77	const struct nhpoly1305_key *key)
	78	{
	79	BUILD_BUG_ON(NH_HASH_BYTES % POLY1305_BLOCK_SIZE != 0);
	80
	81	poly1305_core_blocks(&state->poly_state, &key->poly_key, state->nh_hash,
48ea8c6e	82	NH_HASH_BYTES / POLY1305_BLOCK_SIZE, 1);
26609a21 EB	83	}
	84
	85	/*
	86	* Feed the next portion of the source data, as a whole number of 16-byte
	87	* "NH message units", through NH and Poly1305. Each NH hash is taken over
	88	* 1024 bytes, except possibly the final one which is taken over a multiple of
	89	* 16 bytes up to 1024. Also, in the case where data is passed in misaligned
	90	* chunks, we combine partial hashes; the end result is the same either way.
	91	*/
	92	static void nhpoly1305_units(struct nhpoly1305_state *state,
	93	const struct nhpoly1305_key *key,
	94	const u8 *src, unsigned int srclen, nh_t nh_fn)
	95	{
	96	do {
	97	unsigned int bytes;
	98
	99	if (state->nh_remaining == 0) {
	100	/* Starting a new NH message */
	101	bytes = min_t(unsigned int, srclen, NH_MESSAGE_BYTES);
	102	nh_fn(key->nh_key, src, bytes, state->nh_hash);
	103	state->nh_remaining = NH_MESSAGE_BYTES - bytes;
	104	} else {
	105	/* Continuing a previous NH message */
	106	__le64 tmp_hash[NH_NUM_PASSES];
	107	unsigned int pos;
	108	int i;
	109
	110	pos = NH_MESSAGE_BYTES - state->nh_remaining;
	111	bytes = min(srclen, state->nh_remaining);
	112	nh_fn(&key->nh_key[pos / 4], src, bytes, tmp_hash);
	113	for (i = 0; i < NH_NUM_PASSES; i++)
	114	le64_add_cpu(&state->nh_hash[i],
	115	le64_to_cpu(tmp_hash[i]));
	116	state->nh_remaining -= bytes;
	117	}
	118	if (state->nh_remaining == 0)
	119	process_nh_hash_value(state, key);
	120	src += bytes;
	121	srclen -= bytes;
	122	} while (srclen);
	123	}
	124
	125	int crypto_nhpoly1305_setkey(struct crypto_shash *tfm,
	126	const u8 *key, unsigned int keylen)
	127	{
	128	struct nhpoly1305_key *ctx = crypto_shash_ctx(tfm);
	129	int i;
	130
	131	if (keylen != NHPOLY1305_KEY_SIZE)
	132	return -EINVAL;
	133
	134	poly1305_core_setkey(&ctx->poly_key, key);
	135	key += POLY1305_BLOCK_SIZE;
	136
	137	for (i = 0; i < NH_KEY_WORDS; i++)
	138	ctx->nh_key[i] = get_unaligned_le32(key + i * sizeof(u32));
	139
	140	return 0;
	141	}
	142	EXPORT_SYMBOL(crypto_nhpoly1305_setkey);
	143
	144	int crypto_nhpoly1305_init(struct shash_desc *desc)
	145	{
	146	struct nhpoly1305_state *state = shash_desc_ctx(desc);
147
148	poly1305_core_init(&state->poly_state);
149	state->buflen = 0;
150	state->nh_remaining = 0;
151	return 0;
152	}
153	EXPORT_SYMBOL(crypto_nhpoly1305_init);
154
155	int crypto_nhpoly1305_update_helper(struct shash_desc *desc,
156	const u8 *src, unsigned int srclen,
157	nh_t nh_fn)
158	{
159	struct nhpoly1305_state *state = shash_desc_ctx(desc);
160	const struct nhpoly1305_key *key = crypto_shash_ctx(desc->tfm);
161	unsigned int bytes;
162
163	if (state->buflen) {
164	bytes = min(srclen, (int)NH_MESSAGE_UNIT - state->buflen);
165	memcpy(&state->buffer[state->buflen], src, bytes);
166	state->buflen += bytes;
167	if (state->buflen < NH_MESSAGE_UNIT)
168	return 0;
169	nhpoly1305_units(state, key, state->buffer, NH_MESSAGE_UNIT,
170	nh_fn);
171	state->buflen = 0;
172	src += bytes;
173	srclen -= bytes;
174	}
175
176	if (srclen >= NH_MESSAGE_UNIT) {
177	bytes = round_down(srclen, NH_MESSAGE_UNIT);
178	nhpoly1305_units(state, key, src, bytes, nh_fn);
179	src += bytes;
180	srclen -= bytes;
181	}
182
183	if (srclen) {
184	memcpy(state->buffer, src, srclen);
185	state->buflen = srclen;
186	}
187	return 0;
188	}
189	EXPORT_SYMBOL(crypto_nhpoly1305_update_helper);
190
191	int crypto_nhpoly1305_update(struct shash_desc *desc,
192	const u8 *src, unsigned int srclen)
193	{
194	return crypto_nhpoly1305_update_helper(desc, src, srclen, nh_generic);
195	}
196	EXPORT_SYMBOL(crypto_nhpoly1305_update);
197
198	int crypto_nhpoly1305_final_helper(struct shash_desc desc, u8 dst, nh_t nh_fn)
199	{
200	struct nhpoly1305_state *state = shash_desc_ctx(desc);
201	const struct nhpoly1305_key *key = crypto_shash_ctx(desc->tfm);
202
203	if (state->buflen) {
204	memset(&state->buffer[state->buflen], 0,
205	NH_MESSAGE_UNIT - state->buflen);
206	nhpoly1305_units(state, key, state->buffer, NH_MESSAGE_UNIT,
207	nh_fn);
208	}
209
210	if (state->nh_remaining)
211	process_nh_hash_value(state, key);
212
1c08a104	213	poly1305_core_emit(&state->poly_state, NULL, dst);
26609a21 EB	214	return 0;
	215	}
	216	EXPORT_SYMBOL(crypto_nhpoly1305_final_helper);
	217
	218	int crypto_nhpoly1305_final(struct shash_desc desc, u8 dst)
	219	{
	220	return crypto_nhpoly1305_final_helper(desc, dst, nh_generic);
	221	}
	222	EXPORT_SYMBOL(crypto_nhpoly1305_final);
	223
	224	static struct shash_alg nhpoly1305_alg = {
	225	.base.cra_name = "nhpoly1305",
	226	.base.cra_driver_name = "nhpoly1305-generic",
	227	.base.cra_priority = 100,
	228	.base.cra_ctxsize = sizeof(struct nhpoly1305_key),
	229	.base.cra_module = THIS_MODULE,
	230	.digestsize = POLY1305_DIGEST_SIZE,
	231	.init = crypto_nhpoly1305_init,
	232	.update = crypto_nhpoly1305_update,
	233	.final = crypto_nhpoly1305_final,
	234	.setkey = crypto_nhpoly1305_setkey,
	235	.descsize = sizeof(struct nhpoly1305_state),
	236	};
	237
	238	static int __init nhpoly1305_mod_init(void)
	239	{
	240	return crypto_register_shash(&nhpoly1305_alg);
	241	}
	242
	243	static void __exit nhpoly1305_mod_exit(void)
	244	{
	245	crypto_unregister_shash(&nhpoly1305_alg);
	246	}
	247
c4741b23	248	subsys_initcall(nhpoly1305_mod_init);
26609a21 EB	249	module_exit(nhpoly1305_mod_exit);
	250
	251	MODULE_DESCRIPTION("NHPoly1305 ε-almost-∆-universal hash function");
	252	MODULE_LICENSE("GPL v2");
	253	MODULE_AUTHOR("Eric Biggers <[email protected]>");
	254	MODULE_ALIAS_CRYPTO("nhpoly1305");
	255	MODULE_ALIAS_CRYPTO("nhpoly1305-generic");