56 lines
1.7 KiB
C
56 lines
1.7 KiB
C
/*
|
|
* cifra - embedded cryptography library
|
|
* Written in 2014 by Joseph Birr-Pixton <jpixton@gmail.com>
|
|
*
|
|
* To the extent possible under law, the author(s) have dedicated all
|
|
* copyright and related and neighboring rights to this software to the
|
|
* public domain worldwide. This software is distributed without any
|
|
* warranty.
|
|
*
|
|
* You should have received a copy of the CC0 Public Domain Dedication
|
|
* along with this software. If not, see
|
|
* <http://creativecommons.org/publicdomain/zero/1.0/>.
|
|
*/
|
|
|
|
#ifndef GF128_H
|
|
#define GF128_H
|
|
|
|
#include <stddef.h>
|
|
#include <stdint.h>
|
|
|
|
/**
|
|
* @brief Operations in GF(2^128).
|
|
*
|
|
* These implementations are constant time, but relatively slow.
|
|
*/
|
|
|
|
typedef uint32_t cf_gf128[4];
|
|
|
|
/* Unpack from big-endian bytes into out. */
|
|
void cf_gf128_frombytes_be(const uint8_t in[16], cf_gf128 out);
|
|
|
|
/* Pack in big-endian order into out. */
|
|
void cf_gf128_tobytes_be(const cf_gf128 in, uint8_t out[16]);
|
|
|
|
/* out = 2 * in. Arguments may not alias. */
|
|
void cf_gf128_double(const cf_gf128 in, cf_gf128 out);
|
|
|
|
/* out = 2 * in. Arguments may not alias.
|
|
* This differs from cf_gf128_double because it interprets the
|
|
* block in little endian: the lsb is the msb of the
|
|
* first element, the msb is the lsb of the last element.
|
|
*
|
|
* GCM uses this convention. */
|
|
void cf_gf128_double_le(const cf_gf128 in, cf_gf128 out);
|
|
|
|
/* out = x + y. Arguments may alias. */
|
|
void cf_gf128_add(const cf_gf128 x, const cf_gf128 y, cf_gf128 out);
|
|
|
|
/* out = xy. Arguments may alias.
|
|
*
|
|
* This uses cf_gf128_double_le internally, and is suitable for
|
|
* GCM. */
|
|
void cf_gf128_mul(const cf_gf128 x, const cf_gf128 y, cf_gf128 out);
|
|
|
|
#endif
|