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- /*
- * 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
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