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chacha-set-nonce.c
Daiki Ueno
authored and
Niels Möller
committed
The ChaCha-Poly1305 implementation previously used the chacha_crypt
function that assumes the block counter is 64-bit long, while RFC 8439
defines that the counter is 32-bit long. Although this should be fine
as long as up to 256 gigabytes of data is encrypted with the same key,
it would be nice to use a separate functions (chacha_set_counter32 and
chacha_crypt32) that assume the counter is 32-bit long.
Signed-off-by: 
Daiki Ueno <dueno@redhat.com> chacha-set-nonce.c 2.18 KiB
/* chacha-set-nonce.c
Setting the nonce the ChaCha stream cipher.
Based on the Salsa20 implementation in Nettle.
Copyright (C) 2013 Joachim Strömbergon
Copyright (C) 2012 Simon Josefsson
Copyright (C) 2012, 2014 Niels Möller
This file is part of GNU Nettle.
GNU Nettle is free software: you can redistribute it and/or
modify it under the terms of either:
* the GNU Lesser General Public License as published by the Free
Software Foundation; either version 3 of the License, or (at your
option) any later version.
or
* 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.
or both in parallel, as here.
GNU Nettle is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received copies of the GNU General Public License and
the GNU Lesser General Public License along with this program. If
not, see http://www.gnu.org/licenses/.
*/
/* Based on:
ChaCha specification (doc id: 4027b5256e17b9796842e6d0f68b0b5e) and reference
implementation dated 2008.01.20
D. J. Bernstein
Public domain.
*/
#if HAVE_CONFIG_H
# include "config.h"
#endif
#include <assert.h>
#include "chacha.h"
#include "macros.h"
void
chacha_set_nonce(struct chacha_ctx *ctx, const uint8_t *nonce)
{
ctx->state[12] = 0;
ctx->state[13] = 0;
ctx->state[14] = LE_READ_UINT32(nonce + 0);
ctx->state[15] = LE_READ_UINT32(nonce + 4);
}
void
chacha_set_nonce96(struct chacha_ctx *ctx, const uint8_t *nonce)
{
ctx->state[12] = 0;
ctx->state[13] = LE_READ_UINT32(nonce + 0);
ctx->state[14] = LE_READ_UINT32(nonce + 4);
ctx->state[15] = LE_READ_UINT32(nonce + 8);
}
void
chacha_set_counter(struct chacha_ctx *ctx, const uint8_t *counter)
{
ctx->state[12] = LE_READ_UINT32(counter + 0);
ctx->state[13] = LE_READ_UINT32(counter + 4);
}
void
chacha_set_counter32(struct chacha_ctx *ctx, const uint8_t *counter)
{
ctx->state[12] = LE_READ_UINT32(counter + 0);
}