[linux.git] / crypto / poly1305_generic.c

/*
 * Poly1305 authenticator algorithm, RFC7539
 *
 * Copyright (C) 2015 Martin Willi
 *
 * Based on public domain code by Andrew Moon and Daniel J. Bernstein.
 *
 * 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/internal/hash.h>
#include <crypto/poly1305.h>
#include <linux/crypto.h>
#include <linux/kernel.h>
#include <linux/module.h>

static inline u64 mlt(u64 a, u64 b)
{
	return a * b;
}

static inline u32 sr(u64 v, u_char n)
{
	return v >> n;
}

static inline u32 and(u32 v, u32 mask)
{
	return v & mask;
}

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

int crypto_poly1305_init(struct shash_desc *desc)
{
	struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);

	memset(dctx->h, 0, sizeof(dctx->h));
	dctx->buflen = 0;
	dctx->rset = false;
	dctx->sset = false;

	return 0;
}
EXPORT_SYMBOL_GPL(crypto_poly1305_init);

int crypto_poly1305_setkey(struct crypto_shash *tfm,
			   const u8 *key, unsigned int keylen)
{
	/* Poly1305 requires a unique key for each tag, which implies that
	 * we can't set it on the tfm that gets accessed by multiple users
	 * simultaneously. Instead we expect the key as the first 32 bytes in
	 * the update() call. */
	return -ENOTSUPP;
}
EXPORT_SYMBOL_GPL(crypto_poly1305_setkey);

static void poly1305_setrkey(struct poly1305_desc_ctx *dctx, const u8 *key)
{
	/* r &= 0xffffffc0ffffffc0ffffffc0fffffff */
	dctx->r[0] = (le32_to_cpuvp(key +  0) >> 0) & 0x3ffffff;
	dctx->r[1] = (le32_to_cpuvp(key +  3) >> 2) & 0x3ffff03;
	dctx->r[2] = (le32_to_cpuvp(key +  6) >> 4) & 0x3ffc0ff;
	dctx->r[3] = (le32_to_cpuvp(key +  9) >> 6) & 0x3f03fff;
	dctx->r[4] = (le32_to_cpuvp(key + 12) >> 8) & 0x00fffff;
}

static void poly1305_setskey(struct poly1305_desc_ctx *dctx, const u8 *key)
{
	dctx->s[0] = le32_to_cpuvp(key +  0);
	dctx->s[1] = le32_to_cpuvp(key +  4);
	dctx->s[2] = le32_to_cpuvp(key +  8);
	dctx->s[3] = le32_to_cpuvp(key + 12);
}

unsigned int crypto_poly1305_setdesckey(struct poly1305_desc_ctx *dctx,
					const u8 *src, unsigned int srclen)
{
	if (!dctx->sset) {
		if (!dctx->rset && srclen >= POLY1305_BLOCK_SIZE) {
			poly1305_setrkey(dctx, src);
			src += POLY1305_BLOCK_SIZE;
			srclen -= POLY1305_BLOCK_SIZE;
			dctx->rset = true;
		}
		if (srclen >= POLY1305_BLOCK_SIZE) {
			poly1305_setskey(dctx, src);
			src += POLY1305_BLOCK_SIZE;
			srclen -= POLY1305_BLOCK_SIZE;
			dctx->sset = true;
		}
	}
	return srclen;
}
EXPORT_SYMBOL_GPL(crypto_poly1305_setdesckey);

static unsigned int poly1305_blocks(struct poly1305_desc_ctx *dctx,
				    const u8 *src, unsigned int srclen,
				    u32 hibit)
{
	u32 r0, r1, r2, r3, r4;
	u32 s1, s2, s3, s4;
	u32 h0, h1, h2, h3, h4;
	u64 d0, d1, d2, d3, d4;
	unsigned int datalen;

	if (unlikely(!dctx->sset)) {
		datalen = crypto_poly1305_setdesckey(dctx, src, srclen);
		src += srclen - datalen;
		srclen = datalen;
	}

	r0 = dctx->r[0];
	r1 = dctx->r[1];
	r2 = dctx->r[2];
	r3 = dctx->r[3];
	r4 = dctx->r[4];

	s1 = r1 * 5;
	s2 = r2 * 5;
	s3 = r3 * 5;
	s4 = r4 * 5;

	h0 = dctx->h[0];
	h1 = dctx->h[1];
	h2 = dctx->h[2];
	h3 = dctx->h[3];
	h4 = dctx->h[4];

	while (likely(srclen >= POLY1305_BLOCK_SIZE)) {

		/* h += m[i] */
		h0 += (le32_to_cpuvp(src +  0) >> 0) & 0x3ffffff;
		h1 += (le32_to_cpuvp(src +  3) >> 2) & 0x3ffffff;
		h2 += (le32_to_cpuvp(src +  6) >> 4) & 0x3ffffff;
		h3 += (le32_to_cpuvp(src +  9) >> 6) & 0x3ffffff;
		h4 += (le32_to_cpuvp(src + 12) >> 8) | hibit;

		/* h *= r */
		d0 = mlt(h0, r0) + mlt(h1, s4) + mlt(h2, s3) +
		     mlt(h3, s2) + mlt(h4, s1);
		d1 = mlt(h0, r1) + mlt(h1, r0) + mlt(h2, s4) +
		     mlt(h3, s3) + mlt(h4, s2);
		d2 = mlt(h0, r2) + mlt(h1, r1) + mlt(h2, r0) +
		     mlt(h3, s4) + mlt(h4, s3);
		d3 = mlt(h0, r3) + mlt(h1, r2) + mlt(h2, r1) +
		     mlt(h3, r0) + mlt(h4, s4);
		d4 = mlt(h0, r4) + mlt(h1, r3) + mlt(h2, r2) +
		     mlt(h3, r1) + mlt(h4, r0);

		/* (partial) h %= p */
		d1 += sr(d0, 26);     h0 = and(d0, 0x3ffffff);
		d2 += sr(d1, 26);     h1 = and(d1, 0x3ffffff);
		d3 += sr(d2, 26);     h2 = and(d2, 0x3ffffff);
		d4 += sr(d3, 26);     h3 = and(d3, 0x3ffffff);
		h0 += sr(d4, 26) * 5; h4 = and(d4, 0x3ffffff);
		h1 += h0 >> 26;       h0 = h0 & 0x3ffffff;

		src += POLY1305_BLOCK_SIZE;
		srclen -= POLY1305_BLOCK_SIZE;
	}

	dctx->h[0] = h0;
	dctx->h[1] = h1;
	dctx->h[2] = h2;
	dctx->h[3] = h3;
	dctx->h[4] = h4;

	return srclen;
}

int crypto_poly1305_update(struct shash_desc *desc,
			   const u8 *src, unsigned int srclen)
{
	struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
	unsigned int bytes;

	if (unlikely(dctx->buflen)) {
		bytes = min(srclen, POLY1305_BLOCK_SIZE - dctx->buflen);
		memcpy(dctx->buf + dctx->buflen, src, bytes);
		src += bytes;
		srclen -= bytes;
		dctx->buflen += bytes;

		if (dctx->buflen == POLY1305_BLOCK_SIZE) {
			poly1305_blocks(dctx, dctx->buf,
					POLY1305_BLOCK_SIZE, 1 << 24);
			dctx->buflen = 0;
		}
	}

	if (likely(srclen >= POLY1305_BLOCK_SIZE)) {
		bytes = poly1305_blocks(dctx, src, srclen, 1 << 24);
		src += srclen - bytes;
		srclen = bytes;
	}

	if (unlikely(srclen)) {
		dctx->buflen = srclen;
		memcpy(dctx->buf, src, srclen);
	}

	return 0;
}
EXPORT_SYMBOL_GPL(crypto_poly1305_update);

int crypto_poly1305_final(struct shash_desc *desc, u8 *dst)
{
	struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
	__le32 *mac = (__le32 *)dst;
	u32 h0, h1, h2, h3, h4;
	u32 g0, g1, g2, g3, g4;
	u32 mask;
	u64 f = 0;

	if (unlikely(!dctx->sset))
		return -ENOKEY;

	if (unlikely(dctx->buflen)) {
		dctx->buf[dctx->buflen++] = 1;
		memset(dctx->buf + dctx->buflen, 0,
		       POLY1305_BLOCK_SIZE - dctx->buflen);
		poly1305_blocks(dctx, dctx->buf, POLY1305_BLOCK_SIZE, 0);
	}

	/* fully carry h */
	h0 = dctx->h[0];
	h1 = dctx->h[1];
	h2 = dctx->h[2];
	h3 = dctx->h[3];
	h4 = dctx->h[4];

	h2 += (h1 >> 26);     h1 = h1 & 0x3ffffff;
	h3 += (h2 >> 26);     h2 = h2 & 0x3ffffff;
	h4 += (h3 >> 26);     h3 = h3 & 0x3ffffff;
	h0 += (h4 >> 26) * 5; h4 = h4 & 0x3ffffff;
	h1 += (h0 >> 26);     h0 = h0 & 0x3ffffff;

	/* compute h + -p */
	g0 = h0 + 5;
	g1 = h1 + (g0 >> 26);             g0 &= 0x3ffffff;
	g2 = h2 + (g1 >> 26);             g1 &= 0x3ffffff;
	g3 = h3 + (g2 >> 26);             g2 &= 0x3ffffff;
	g4 = h4 + (g3 >> 26) - (1 << 26); g3 &= 0x3ffffff;

	/* select h if h < p, or h + -p if h >= p */
	mask = (g4 >> ((sizeof(u32) * 8) - 1)) - 1;
	g0 &= mask;
	g1 &= mask;
	g2 &= mask;
	g3 &= mask;
	g4 &= mask;
	mask = ~mask;
	h0 = (h0 & mask) | g0;
	h1 = (h1 & mask) | g1;
	h2 = (h2 & mask) | g2;
	h3 = (h3 & mask) | g3;
	h4 = (h4 & mask) | g4;

	/* h = h % (2^128) */
	h0 = (h0 >>  0) | (h1 << 26);
	h1 = (h1 >>  6) | (h2 << 20);
	h2 = (h2 >> 12) | (h3 << 14);
	h3 = (h3 >> 18) | (h4 <<  8);

	/* mac = (h + s) % (2^128) */
	f = (f >> 32) + h0 + dctx->s[0]; mac[0] = cpu_to_le32(f);
	f = (f >> 32) + h1 + dctx->s[1]; mac[1] = cpu_to_le32(f);
	f = (f >> 32) + h2 + dctx->s[2]; mac[2] = cpu_to_le32(f);
	f = (f >> 32) + h3 + dctx->s[3]; mac[3] = cpu_to_le32(f);

	return 0;
}
EXPORT_SYMBOL_GPL(crypto_poly1305_final);

static struct shash_alg poly1305_alg = {
	.digestsize	= POLY1305_DIGEST_SIZE,
	.init		= crypto_poly1305_init,
	.update		= crypto_poly1305_update,
	.final		= crypto_poly1305_final,
	.setkey		= crypto_poly1305_setkey,
	.descsize	= sizeof(struct poly1305_desc_ctx),
	.base		= {
		.cra_name		= "poly1305",
		.cra_driver_name	= "poly1305-generic",
		.cra_priority		= 100,
		.cra_flags		= CRYPTO_ALG_TYPE_SHASH,
		.cra_alignmask		= sizeof(u32) - 1,
		.cra_blocksize		= POLY1305_BLOCK_SIZE,
		.cra_module		= THIS_MODULE,
	},
};

static int __init poly1305_mod_init(void)
{
	return crypto_register_shash(&poly1305_alg);
}

static void __exit poly1305_mod_exit(void)
{
	crypto_unregister_shash(&poly1305_alg);
}

module_init(poly1305_mod_init);
module_exit(poly1305_mod_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Martin Willi <[email protected]>");
MODULE_DESCRIPTION("Poly1305 authenticator");
MODULE_ALIAS_CRYPTO("poly1305");
MODULE_ALIAS_CRYPTO("poly1305-generic");
Commit	Line	Data
f979e014 MW	1	/*
	2	* Poly1305 authenticator algorithm, RFC7539
	3	*
	4	* Copyright (C) 2015 Martin Willi
	5	*
	6	* Based on public domain code by Andrew Moon and Daniel J. Bernstein.
	7	*
	8	* This program is free software; you can redistribute it and/or modify
	9	* it under the terms of the GNU General Public License as published by
	10	* the Free Software Foundation; either version 2 of the License, or
	11	* (at your option) any later version.
	12	*/
	13
	14	#include <crypto/algapi.h>
	15	#include <crypto/internal/hash.h>
2546f811	16	#include <crypto/poly1305.h>
f979e014 MW	17	#include <linux/crypto.h>
	18	#include <linux/kernel.h>
	19	#include <linux/module.h>
	20
f979e014 MW	21	static inline u64 mlt(u64 a, u64 b)
	22	{
	23	return a * b;
	24	}
	25
	26	static inline u32 sr(u64 v, u_char n)
	27	{
	28	return v >> n;
	29	}
	30
	31	static inline u32 and(u32 v, u32 mask)
	32	{
	33	return v & mask;
	34	}
	35
	36	static inline u32 le32_to_cpuvp(const void *p)
	37	{
	38	return le32_to_cpup(p);
	39	}
	40
2546f811	41	int crypto_poly1305_init(struct shash_desc *desc)
f979e014 MW	42	{
	43	struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
	44
	45	memset(dctx->h, 0, sizeof(dctx->h));
	46	dctx->buflen = 0;
c2b7b20a MW	47	dctx->rset = false;
c2b7b20a MW	48	dctx->sset = false;
f979e014 MW	49
	50	return 0;
	51	}
2546f811	52	EXPORT_SYMBOL_GPL(crypto_poly1305_init);
f979e014	53
2546f811	54	int crypto_poly1305_setkey(struct crypto_shash *tfm,
f979e014 MW	55	const u8 *key, unsigned int keylen)
f979e014 MW	56	{
c2b7b20a MW	57	/* Poly1305 requires a unique key for each tag, which implies that
	58	* we can't set it on the tfm that gets accessed by multiple users
	59	* simultaneously. Instead we expect the key as the first 32 bytes in
	60	* the update() call. */
	61	return -ENOTSUPP;
	62	}
2546f811	63	EXPORT_SYMBOL_GPL(crypto_poly1305_setkey);
f979e014	64
c2b7b20a MW	65	static void poly1305_setrkey(struct poly1305_desc_ctx dctx, const u8 key)
c2b7b20a MW	66	{
f979e014	67	/* r &= 0xffffffc0ffffffc0ffffffc0fffffff */
c2b7b20a MW	68	dctx->r[0] = (le32_to_cpuvp(key + 0) >> 0) & 0x3ffffff;
	69	dctx->r[1] = (le32_to_cpuvp(key + 3) >> 2) & 0x3ffff03;
	70	dctx->r[2] = (le32_to_cpuvp(key + 6) >> 4) & 0x3ffc0ff;
	71	dctx->r[3] = (le32_to_cpuvp(key + 9) >> 6) & 0x3f03fff;
	72	dctx->r[4] = (le32_to_cpuvp(key + 12) >> 8) & 0x00fffff;
	73	}
f979e014	74
c2b7b20a MW	75	static void poly1305_setskey(struct poly1305_desc_ctx dctx, const u8 key)
	76	{
	77	dctx->s[0] = le32_to_cpuvp(key + 0);
	78	dctx->s[1] = le32_to_cpuvp(key + 4);
	79	dctx->s[2] = le32_to_cpuvp(key + 8);
	80	dctx->s[3] = le32_to_cpuvp(key + 12);
f979e014 MW	81	}
f979e014 MW	82
2546f811 MW	83	unsigned int crypto_poly1305_setdesckey(struct poly1305_desc_ctx *dctx,
2546f811 MW	84	const u8 *src, unsigned int srclen)
f979e014	85	{
2546f811	86	if (!dctx->sset) {
c2b7b20a MW	87	if (!dctx->rset && srclen >= POLY1305_BLOCK_SIZE) {
	88	poly1305_setrkey(dctx, src);
	89	src += POLY1305_BLOCK_SIZE;
	90	srclen -= POLY1305_BLOCK_SIZE;
	91	dctx->rset = true;
	92	}
	93	if (srclen >= POLY1305_BLOCK_SIZE) {
	94	poly1305_setskey(dctx, src);
	95	src += POLY1305_BLOCK_SIZE;
	96	srclen -= POLY1305_BLOCK_SIZE;
	97	dctx->sset = true;
	98	}
	99	}
2546f811 MW	100	return srclen;
	101	}
	102	EXPORT_SYMBOL_GPL(crypto_poly1305_setdesckey);
	103
	104	static unsigned int poly1305_blocks(struct poly1305_desc_ctx *dctx,
	105	const u8 *src, unsigned int srclen,
	106	u32 hibit)
	107	{
	108	u32 r0, r1, r2, r3, r4;
	109	u32 s1, s2, s3, s4;
	110	u32 h0, h1, h2, h3, h4;
	111	u64 d0, d1, d2, d3, d4;
	112	unsigned int datalen;
	113
	114	if (unlikely(!dctx->sset)) {
	115	datalen = crypto_poly1305_setdesckey(dctx, src, srclen);
	116	src += srclen - datalen;
	117	srclen = datalen;
	118	}
c2b7b20a MW	119
	120	r0 = dctx->r[0];
	121	r1 = dctx->r[1];
	122	r2 = dctx->r[2];
	123	r3 = dctx->r[3];
	124	r4 = dctx->r[4];
f979e014 MW	125
	126	s1 = r1 * 5;
	127	s2 = r2 * 5;
	128	s3 = r3 * 5;
	129	s4 = r4 * 5;
	130
	131	h0 = dctx->h[0];
	132	h1 = dctx->h[1];
	133	h2 = dctx->h[2];
	134	h3 = dctx->h[3];
	135	h4 = dctx->h[4];
	136
	137	while (likely(srclen >= POLY1305_BLOCK_SIZE)) {
	138
	139	/* h += m[i] */
	140	h0 += (le32_to_cpuvp(src + 0) >> 0) & 0x3ffffff;
	141	h1 += (le32_to_cpuvp(src + 3) >> 2) & 0x3ffffff;
	142	h2 += (le32_to_cpuvp(src + 6) >> 4) & 0x3ffffff;
	143	h3 += (le32_to_cpuvp(src + 9) >> 6) & 0x3ffffff;
	144	h4 += (le32_to_cpuvp(src + 12) >> 8) \| hibit;
	145
	146	/* h = r /
	147	d0 = mlt(h0, r0) + mlt(h1, s4) + mlt(h2, s3) +
	148	mlt(h3, s2) + mlt(h4, s1);
	149	d1 = mlt(h0, r1) + mlt(h1, r0) + mlt(h2, s4) +
	150	mlt(h3, s3) + mlt(h4, s2);
	151	d2 = mlt(h0, r2) + mlt(h1, r1) + mlt(h2, r0) +
	152	mlt(h3, s4) + mlt(h4, s3);
	153	d3 = mlt(h0, r3) + mlt(h1, r2) + mlt(h2, r1) +
	154	mlt(h3, r0) + mlt(h4, s4);
	155	d4 = mlt(h0, r4) + mlt(h1, r3) + mlt(h2, r2) +
	156	mlt(h3, r1) + mlt(h4, r0);
	157
	158	/* (partial) h %= p */
	159	d1 += sr(d0, 26); h0 = and(d0, 0x3ffffff);
	160	d2 += sr(d1, 26); h1 = and(d1, 0x3ffffff);
	161	d3 += sr(d2, 26); h2 = and(d2, 0x3ffffff);
	162	d4 += sr(d3, 26); h3 = and(d3, 0x3ffffff);
	163	h0 += sr(d4, 26) * 5; h4 = and(d4, 0x3ffffff);
	164	h1 += h0 >> 26; h0 = h0 & 0x3ffffff;
	165
	166	src += POLY1305_BLOCK_SIZE;
	167	srclen -= POLY1305_BLOCK_SIZE;
	168	}
	169
	170	dctx->h[0] = h0;
	171	dctx->h[1] = h1;
	172	dctx->h[2] = h2;
	173	dctx->h[3] = h3;
	174	dctx->h[4] = h4;
	175
	176	return srclen;
	177	}
	178
2546f811	179	int crypto_poly1305_update(struct shash_desc *desc,
f979e014 MW	180	const u8 *src, unsigned int srclen)
	181	{
	182	struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
f979e014 MW	183	unsigned int bytes;
	184
	185	if (unlikely(dctx->buflen)) {
	186	bytes = min(srclen, POLY1305_BLOCK_SIZE - dctx->buflen);
	187	memcpy(dctx->buf + dctx->buflen, src, bytes);
	188	src += bytes;
	189	srclen -= bytes;
	190	dctx->buflen += bytes;
	191
	192	if (dctx->buflen == POLY1305_BLOCK_SIZE) {
c2b7b20a	193	poly1305_blocks(dctx, dctx->buf,
f979e014 MW	194	POLY1305_BLOCK_SIZE, 1 << 24);
	195	dctx->buflen = 0;
	196	}
	197	}
	198
	199	if (likely(srclen >= POLY1305_BLOCK_SIZE)) {
c2b7b20a	200	bytes = poly1305_blocks(dctx, src, srclen, 1 << 24);
f979e014 MW	201	src += srclen - bytes;
	202	srclen = bytes;
	203	}
	204
	205	if (unlikely(srclen)) {
	206	dctx->buflen = srclen;
	207	memcpy(dctx->buf, src, srclen);
	208	}
	209
	210	return 0;
	211	}
2546f811	212	EXPORT_SYMBOL_GPL(crypto_poly1305_update);
f979e014	213
2546f811	214	int crypto_poly1305_final(struct shash_desc desc, u8 dst)
f979e014 MW	215	{
f979e014 MW	216	struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
f979e014 MW	217	__le32 mac = (__le32 )dst;
	218	u32 h0, h1, h2, h3, h4;
	219	u32 g0, g1, g2, g3, g4;
	220	u32 mask;
	221	u64 f = 0;
	222
c2b7b20a MW	223	if (unlikely(!dctx->sset))
	224	return -ENOKEY;
	225
f979e014 MW	226	if (unlikely(dctx->buflen)) {
	227	dctx->buf[dctx->buflen++] = 1;
	228	memset(dctx->buf + dctx->buflen, 0,
	229	POLY1305_BLOCK_SIZE - dctx->buflen);
c2b7b20a	230	poly1305_blocks(dctx, dctx->buf, POLY1305_BLOCK_SIZE, 0);
f979e014 MW	231	}
	232
	233	/* fully carry h */
	234	h0 = dctx->h[0];
	235	h1 = dctx->h[1];
	236	h2 = dctx->h[2];
	237	h3 = dctx->h[3];
	238	h4 = dctx->h[4];
	239
	240	h2 += (h1 >> 26); h1 = h1 & 0x3ffffff;
	241	h3 += (h2 >> 26); h2 = h2 & 0x3ffffff;
	242	h4 += (h3 >> 26); h3 = h3 & 0x3ffffff;
	243	h0 += (h4 >> 26) * 5; h4 = h4 & 0x3ffffff;
	244	h1 += (h0 >> 26); h0 = h0 & 0x3ffffff;
	245
	246	/* compute h + -p */
	247	g0 = h0 + 5;
	248	g1 = h1 + (g0 >> 26); g0 &= 0x3ffffff;
	249	g2 = h2 + (g1 >> 26); g1 &= 0x3ffffff;
	250	g3 = h3 + (g2 >> 26); g2 &= 0x3ffffff;
	251	g4 = h4 + (g3 >> 26) - (1 << 26); g3 &= 0x3ffffff;
	252
	253	/* select h if h < p, or h + -p if h >= p */
	254	mask = (g4 >> ((sizeof(u32) * 8) - 1)) - 1;
	255	g0 &= mask;
	256	g1 &= mask;
	257	g2 &= mask;
	258	g3 &= mask;
	259	g4 &= mask;
	260	mask = ~mask;
	261	h0 = (h0 & mask) \| g0;
	262	h1 = (h1 & mask) \| g1;
	263	h2 = (h2 & mask) \| g2;
	264	h3 = (h3 & mask) \| g3;
	265	h4 = (h4 & mask) \| g4;
	266
	267	/* h = h % (2^128) */
	268	h0 = (h0 >> 0) \| (h1 << 26);
	269	h1 = (h1 >> 6) \| (h2 << 20);
	270	h2 = (h2 >> 12) \| (h3 << 14);
	271	h3 = (h3 >> 18) \| (h4 << 8);
	272
	273	/* mac = (h + s) % (2^128) */
c2b7b20a MW	274	f = (f >> 32) + h0 + dctx->s[0]; mac[0] = cpu_to_le32(f);
	275	f = (f >> 32) + h1 + dctx->s[1]; mac[1] = cpu_to_le32(f);
	276	f = (f >> 32) + h2 + dctx->s[2]; mac[2] = cpu_to_le32(f);
	277	f = (f >> 32) + h3 + dctx->s[3]; mac[3] = cpu_to_le32(f);
f979e014 MW	278
	279	return 0;
	280	}
2546f811	281	EXPORT_SYMBOL_GPL(crypto_poly1305_final);
f979e014 MW	282
	283	static struct shash_alg poly1305_alg = {
	284	.digestsize = POLY1305_DIGEST_SIZE,
2546f811 MW	285	.init = crypto_poly1305_init,
	286	.update = crypto_poly1305_update,
	287	.final = crypto_poly1305_final,
	288	.setkey = crypto_poly1305_setkey,
f979e014 MW	289	.descsize = sizeof(struct poly1305_desc_ctx),
	290	.base = {
	291	.cra_name = "poly1305",
	292	.cra_driver_name = "poly1305-generic",
	293	.cra_priority = 100,
	294	.cra_flags = CRYPTO_ALG_TYPE_SHASH,
	295	.cra_alignmask = sizeof(u32) - 1,
	296	.cra_blocksize = POLY1305_BLOCK_SIZE,
f979e014 MW	297	.cra_module = THIS_MODULE,
	298	},
	299	};
	300
	301	static int __init poly1305_mod_init(void)
	302	{
	303	return crypto_register_shash(&poly1305_alg);
	304	}
	305
	306	static void __exit poly1305_mod_exit(void)
	307	{
	308	crypto_unregister_shash(&poly1305_alg);
	309	}
	310
	311	module_init(poly1305_mod_init);
	312	module_exit(poly1305_mod_exit);
	313
	314	MODULE_LICENSE("GPL");
	315	MODULE_AUTHOR("Martin Willi <[email protected]>");
	316	MODULE_DESCRIPTION("Poly1305 authenticator");
	317	MODULE_ALIAS_CRYPTO("poly1305");
	318	MODULE_ALIAS_CRYPTO("poly1305-generic");