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/**
* libkeccak – Keccak-family hashing library
*
* Copyright © 2014 Mattias Andrée (maandree@member.fsf.org)
*
* This library is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This library 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this library. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef LIBKECCAK_SPEC_H
#define LIBKECCAK_SPEC_H 1
#include <limits.h>
/**
* Message suffix for SHA3 hashing
*/
#define LIBKECCAK_SHA3_SUFFIX "01"
/**
* Message suffix for RawSHAKE hashing
*/
#define LIBKECCAK_RAWSHAKE_SUFFIX "11"
/**
* Message suffix for SHAKE hashing
*/
#define LIBKECCAK_SHAKE_SUFFIX "1111"
/**
* Invalid `libkeccak_spec_t.bitrate`: non-positive
*/
#define LIBKECCAK_SPEC_ERROR_BITRATE_NONPOSITIVE 1
/**
* Invalid `libkeccak_spec_t.bitrate`: not a multiple of 8
*/
#define LIBKECCAK_SPEC_ERROR_BITRATE_MOD_8 2
/**
* Invalid `libkeccak_spec_t.capacity`: non-positive
*/
#define LIBKECCAK_SPEC_ERROR_CAPACITY_NONPOSITIVE 3
/**
* Invalid `libkeccak_spec_t.capacity`: not a multiple of 8
*/
#define LIBKECCAK_SPEC_ERROR_CAPACITY_MOD_8 4
/**
* Invalid `libkeccak_spec_t.output`: non-positive
*/
#define LIBKECCAK_SPEC_ERROR_OUTPUT_NONPOSITIVE 5
/**
* Invalid `libkeccak_spec_t` values: `.bitrate + `.capacity`
* is greater 1600 which is the largest supported state size
*/
#define LIBKECCAK_SPEC_ERROR_STATE_TOO_LARGE 6
/**
* Invalid `libkeccak_spec_t` values:
* `.bitrate + `.capacity` is not a multiple of 25
*/
#define LIBKECCAK_SPEC_ERROR_STATE_MOD_25 7
/**
* Invalid `libkeccak_spec_t` values: `.bitrate + `.capacity`
* is a not a 2-potent multiple of 25
*/
#define LIBKECCAK_SPEC_ERROR_WORD_NON_2_POTENT 8
/**
* Datastructure that describes the parameters
* that should be used when hashing
*/
typedef struct libkeccak_spec
{
/**
* The bitrate
*/
long bitrate;
/**
* The capacity
*/
long capacity;
/**
* The output size
*/
long output;
} libkeccak_spec_t;
/**
* Fill in a `libkeccak_spec_t` for a SHA3-x hashing
*
* @param spec The specifications datastructure to fill in
* @param x The value of x in `SHA3-x`, the output size
*/
static inline __attribute__((nonnull, nothrow))
void libkeccak_spec_sha3(libkeccak_spec_t* restrict spec, long x)
{
spec->bitrate = 1600 - 2 * x;
spec->capacity = 2 * x;
spec->output = x;
}
/**
* Fill in a `libkeccak_spec_t` for a RawSHAKEx hashing
*
* @param spec The specifications datastructure to fill in
* @param x The value of x in `RawSHAKEx`, half the capacity
* @param d The output size
*/
static inline __attribute__((nonnull, nothrow))
void libkeccak_spec_rawshake(libkeccak_spec_t* restrict spec, long x, long d)
{
spec->bitrate = 1600 - 2 * x;
spec->capacity = 2 * x;
spec->output = d;
}
/**
* Fill in a `libkeccak_spec_t` for a SHAKEx hashing
*
* @param spec:libkeccak_spec_t* The specifications datastructure to fill in
* @param x:long The value of x in `SHAKEx`, half the capacity
* @param d:long The output size
*/
#define libkeccak_spec_shake libkeccak_spec_rawshake
/**
* Check for errors in a `libkeccak_spec_t`
*
* @param spec The specifications datastructure to check
* @return Zero if error free, a `LIBKECCAK_SPEC_ERROR_*` if an error was found
*/
static inline __attribute__((nonnull, nothrow, unused, warn_unused_result, pure))
int libkeccak_spec_check(const libkeccak_spec_t* restrict spec)
{
long state_size = spec->capacity + spec->bitrate, n_state_size;
if (spec->bitrate <= 0) return LIBKECCAK_SPEC_ERROR_BITRATE_NONPOSITIVE;
if (spec->bitrate % 8) return LIBKECCAK_SPEC_ERROR_BITRATE_MOD_8;
if (spec->capacity <= 0) return LIBKECCAK_SPEC_ERROR_CAPACITY_NONPOSITIVE;
if (spec->capacity % 8) return LIBKECCAK_SPEC_ERROR_CAPACITY_MOD_8;
if (spec->output <= 0) return LIBKECCAK_SPEC_ERROR_OUTPUT_NONPOSITIVE;
if (state_size > 1600) return LIBKECCAK_SPEC_ERROR_STATE_TOO_LARGE;
if (state_size % 25) return LIBKECCAK_SPEC_ERROR_STATE_MOD_25;
state_size /= 25;
/* This is a portable implementation of `(x & -x) != x` which assumes
* two's complement, which of course is always satisfied by GCC, but anyway... */
n_state_size = ((~state_size) ^ (LONG_MIN & ~LONG_MAX)) + 1;
if ((state_size & n_state_size) != state_size)
return LIBKECCAK_SPEC_ERROR_WORD_NON_2_POTENT;
return 0;
}
#endif
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