internal-keccak.h

/*
 * Copyright (C) 2020 Southern Storm Software, Pty Ltd.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
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 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
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 *
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 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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 */

#ifndef LW_INTERNAL_KECCAK_H
#define LW_INTERNAL_KECCAK_H

#include "internal-util.h"

/**
 * \file internal-keccak.h
 * \brief Internal implementation of the Keccak-p permutation.
 */

#ifdef __cplusplus
extern "C" {
#endif

/**
 * \brief Size of the state for the Keccak-p[200] permutation.
 */
#define KECCAKP_200_STATE_SIZE 25

/**
 * \brief Size of the state for the Keccak-p[400] permutation.
 */
#define KECCAKP_400_STATE_SIZE 50

/**
 * \brief Structure of the internal state of the Keccak-p[200] permutation.
 */
typedef union
{
    uint8_t A[5][5];    /**< Keccak-p[200] state as a 5x5 array of lanes */
    uint8_t B[25];      /**< Keccak-p[200] state as a byte array */

} keccakp_200_state_t;

/**
 * \brief Structure of the internal state of the Keccak-p[400] permutation.
 */
typedef union
{
    uint16_t A[5][5];   /**< Keccak-p[400] state as a 5x5 array of lanes */
    uint8_t B[50];      /**< Keccak-p[400] state as a byte array */

} keccakp_400_state_t;

/**
 * \brief Permutes the Keccak-p[200] state.
 *
 * \param state The Keccak-p[200] state to be permuted.
 */
void keccakp_200_permute(keccakp_200_state_t *state);

/**
 * \brief Permutes the Keccak-p[400] state, which is assumed to be in
 * little-endian byte order.
 *
 * \param state The Keccak-p[400] state to be permuted.
 * \param rounds The number of rounds to perform (up to 20).
 */
void keccakp_400_permute(keccakp_400_state_t *state, unsigned rounds);

#ifdef __cplusplus
}
#endif

#endif