/**
 * \file sha256.h
 *
 * \brief This file contains SHA-224 and SHA-256 definitions and functions.
 *
 * The Secure Hash Algorithms 224 and 256 (SHA-224 and SHA-256) cryptographic
 * hash functions are defined in <em>FIPS 180-4: Secure Hash Standard (SHS)</em>.
 */
/*
 *  Copyright (C) 2006-2018, Arm Limited (or its affiliates), All Rights Reserved
 *  Copyright (C) 2018, Intel Corporation, All Rights Reserved.
 *  SPDX-License-Identifier: Apache-2.0
 *
 *  Licensed under the Apache License, Version 2.0 (the "License"); you may
 *  not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *  This file is part of Mbed TLS (https://tls.mbed.org)
 */
#ifndef MBEDTLS_SHA256_H
#define MBEDTLS_SHA256_H

#include <types.h>

/**
 * \brief          The SHA-256 context structure.
 *
 *                 The structure is used both for SHA-256 and for SHA-224
 *                 checksum calculations. The choice between these two is
 *                 made in the call to mbedtls_sha256_starts_ret().
 */
typedef struct
{
    uint32_t total[2];          /*!< The number of Bytes processed.  */
    uint32_t state[8];          /*!< The intermediate digest state.  */
    uint8_t buffer[64];   /*!< The data block being processed. */
    int32_t is224;                  /*!< Determines which function to use:
                                     0: Use SHA-256, or 1: Use SHA-224. */
}
mbedtls_sha256_context;

/**
 * \brief          This function initializes a SHA-256 context.
 *
 * \param ctx      The SHA-256 context to initialize.
 */
void mbedtls_sha256_init( mbedtls_sha256_context *ctx );

/**
 * \brief          This function clears a SHA-256 context.
 *
 * \param ctx      The SHA-256 context to clear.
 */
void mbedtls_sha256_free( mbedtls_sha256_context *ctx );

/**
 * \brief          This function clones the state of a SHA-256 context.
 *
 * \param dst      The destination context.
 * \param src      The context to clone.
 */
void mbedtls_sha256_clone( mbedtls_sha256_context *dst,
                           const mbedtls_sha256_context *src );

/**
 * \brief          This function starts a SHA-224 or SHA-256 checksum
 *                 calculation.
 *
 * \param ctx      The context to initialize.
 * \param is224    Determines which function to use:
 *                 0: Use SHA-256, or 1: Use SHA-224.
 *
 * \return         \c 0 on success.
 */
int32_t mbedtls_sha256_starts_ret( mbedtls_sha256_context *ctx, int32_t is224 );

/**
 * \brief          This function feeds an input buffer into an ongoing
 *                 SHA-256 checksum calculation.
 *
 * \param ctx      The SHA-256 context.
 * \param input    The buffer holding the data.
 * \param ilen     The length of the input data.
 *
 * \return         \c 0 on success.
 */
int32_t mbedtls_sha256_update_ret( mbedtls_sha256_context *ctx,
                               const uint8_t *input,
                               size_t ilen );

/**
 * \brief          This function finishes the SHA-256 operation, and writes
 *                 the result to the output buffer.
 *
 * \param ctx      The SHA-256 context.
 * \param output   The SHA-224 or SHA-256 checksum result.
 *
 * \return         \c 0 on success.
 */
int32_t mbedtls_sha256_finish_ret( mbedtls_sha256_context *ctx,
                               uint8_t output[32] );

/**
 * \brief          This function processes a single data block within
 *                 the ongoing SHA-256 computation. This function is for
 *                 internal use only.
 *
 * \param ctx      The SHA-256 context.
 * \param data     The buffer holding one block of data.
 *
 * \return         \c 0 on success.
 */
int32_t mbedtls_internal_sha256_process( mbedtls_sha256_context *ctx,
                                     const uint8_t data[64] );

/**
 * \brief          This function calculates the SHA-224 or SHA-256
 *                 checksum of a buffer.
 *
 *                 The function allocates the context, performs the
 *                 calculation, and frees the context.
 *
 *                 The SHA-256 result is calculated as
 *                 output = SHA-256(input buffer).
 *
 * \param input    The buffer holding the input data.
 * \param ilen     The length of the input data.
 * \param output   The SHA-224 or SHA-256 checksum result.
 * \param is224    Determines which function to use:
 *                 0: Use SHA-256, or 1: Use SHA-224.
 */
int32_t mbedtls_sha256_ret( const uint8_t *input,
                        size_t ilen,
                        uint8_t output[32],
                        int32_t is224 );

#endif /* mbedtls_sha256.h */