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/*
* 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/internal/poly1305.h>
#include <linux/crypto.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/unaligned.h>
static int crypto_poly1305_init(struct shash_desc *desc)
{
struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
poly1305_core_init(&dctx->h);
dctx->buflen = 0;
dctx->rset = 0;
dctx->sset = false;
return 0;
}
static 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_core_setkey(&dctx->core_r, src);
src += POLY1305_BLOCK_SIZE;
srclen -= POLY1305_BLOCK_SIZE;
dctx->rset = 2;
}
if (srclen >= POLY1305_BLOCK_SIZE) {
dctx->s[0] = get_unaligned_le32(src + 0);
dctx->s[1] = get_unaligned_le32(src + 4);
dctx->s[2] = get_unaligned_le32(src + 8);
dctx->s[3] = get_unaligned_le32(src + 12);
src += POLY1305_BLOCK_SIZE;
srclen -= POLY1305_BLOCK_SIZE;
dctx->sset = true;
}
}
return srclen;
}
static void poly1305_blocks(struct poly1305_desc_ctx *dctx, const u8 *src,
unsigned int srclen)
{
unsigned int datalen;
if (unlikely(!dctx->sset)) {
datalen = crypto_poly1305_setdesckey(dctx, src, srclen);
src += srclen - datalen;
srclen = datalen;
}
poly1305_core_blocks(&dctx->h, &dctx->core_r, src,
srclen / POLY1305_BLOCK_SIZE, 1);
}
static 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);
dctx->buflen = 0;
}
}
if (likely(srclen >= POLY1305_BLOCK_SIZE)) {
poly1305_blocks(dctx, src, srclen);
src += srclen - (srclen % POLY1305_BLOCK_SIZE);
srclen %= POLY1305_BLOCK_SIZE;
}
if (unlikely(srclen)) {
dctx->buflen = srclen;
memcpy(dctx->buf, src, srclen);
}
return 0;
}
static int crypto_poly1305_final(struct shash_desc *desc, u8 *dst)
{
struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
if (unlikely(!dctx->sset))
return -ENOKEY;
poly1305_final_generic(dctx, dst);
return 0;
}
static struct shash_alg poly1305_alg = {
.digestsize = POLY1305_DIGEST_SIZE,
.init = crypto_poly1305_init,
.update = crypto_poly1305_update,
.final = crypto_poly1305_final,
.descsize = sizeof(struct poly1305_desc_ctx),
.base = {
.cra_name = "poly1305",
.cra_driver_name = "poly1305-generic",
.cra_priority = 100,
.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);
}
subsys_initcall(poly1305_mod_init);
module_exit(poly1305_mod_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Martin Willi <martin@strongswan.org>");
MODULE_DESCRIPTION("Poly1305 authenticator");
MODULE_ALIAS_CRYPTO("poly1305");
MODULE_ALIAS_CRYPTO("poly1305-generic");
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