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Lucas Gabriel Vuotto 2024-05-31 10:59:58 +00:00
commit 7bc527c769
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aead_chacha20_poly1305.c Normal file
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/*
* Copyright (c) 2024 Lucas Gabriel Vuotto <lucas@lgv5.net>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include "lilcrypto.h"
#include "aead.h"
#include "auth_poly1305.h"
#include "cipher_chacha20.h"
#include "impl_chacha20.h"
#include "impl_poly1305.h"
#include "util.h"
/*
* Implements ChaCha20-Poly1305 according to RFC 8439.
*/
static uint8_t zeropad[16];
static int
chacha20_poly1305_seal(const uint8_t *key, size_t keylen, const uint8_t *iv,
size_t ivlen, uint8_t *out, size_t *outlen, const uint8_t *aad,
size_t aadlen, const uint8_t *in, size_t inlen)
{
struct chacha20_ctx cctx;
struct poly1305_ctx pctx;
uint8_t poly1305_key[LC_POLY1305_KEYLEN];
uint8_t buf[sizeof(uint64_t) * 2];
size_t i, olen;
if (inlen > UINT64_MAX || aadlen > UINT64_MAX ||
inlen > SIZE_MAX - LC_POLY1305_TAGLEN ||
inlen > SIZE_MAX - CHACHA20_CHUNK + 1 ||
(inlen + CHACHA20_CHUNK - 1) / CHACHA20_CHUNK >
CHACHA20_CTRMAX - 1) {
if (out == NULL)
*outlen = 0;
return 0;
}
if (out == NULL) {
*outlen = inlen + LC_POLY1305_TAGLEN;
return 1;
}
*outlen = 0;
for (i = 0; i < LC_POLY1305_KEYLEN; i++)
poly1305_key[i] = 0;
if (!chacha20_x_init(&cctx, key, keylen, iv, ivlen) ||
!chacha20_x_update(&cctx, poly1305_key, &olen, poly1305_key,
LC_POLY1305_KEYLEN))
return 0;
for (i = 0; i < LC_POLY1305_KEYLEN / sizeof(uint32_t); i++)
store32le(&poly1305_key[i * 4], cctx.s[i]);
if (!poly1305_init(&pctx, poly1305_key, LC_POLY1305_KEYLEN) ||
!poly1305_update(&pctx, aad, aadlen))
return 0;
if (aadlen % 16 != 0)
if (!poly1305_update(&pctx, zeropad, 16 - (aadlen % 16)))
return 0;
if (!chacha20_x_init_from(&cctx, key, keylen, iv, ivlen, 1))
return 0;
if (!chacha20_x_update(&cctx, out, &olen, in, inlen))
return 0;
*outlen = olen;
if (!chacha20_x_final(&cctx, out + olen, &olen))
return 0;
if (!poly1305_update(&pctx, out, inlen))
return 0;
if (inlen % 16 != 0)
if (!poly1305_update(&pctx, zeropad, 16 - (inlen % 16)))
return 0;
store64le(&buf[0], aadlen);
store64le(&buf[sizeof(uint64_t)], inlen);
if (!poly1305_update(&pctx, buf, sizeof(buf)) ||
!poly1305_final(&pctx, out + inlen, &olen))
return 0;
lc_scrub(buf, sizeof(buf));
lc_scrub(poly1305_key, sizeof(poly1305_key));
*outlen = inlen + LC_POLY1305_TAGLEN;
return 1;
}
static struct lc_aead_impl chacha20_poly1305_impl = {
.seal = &chacha20_poly1305_seal,
.open = NULL, //&chacha20_poly1305_open,
};
const struct lc_aead_impl *
lc_aead_impl_chacha20_poly1305(void)
{
return &chacha20_poly1305_impl;
}