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/* sha256.h - TinyCrypt interface to a SHA-256 implementation */
/*
* Copyright (C) 2015 by Intel Corporation, All Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* - Neither the name of Intel Corporation nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/**
* @file
* @brief Interface to a SHA-256 implementation.
*
* Overview: SHA-256 is a NIST approved cryptographic hashing algorithm
* specified in FIPS 180. A hash algorithm maps data of arbitrary
* size to data of fixed length.
*
* Security: SHA-256 provides 128 bits of security against collision attacks
* and 256 bits of security against pre-image attacks. SHA-256 does
* NOT behave like a random oracle, but it can be used as one if
* the string being hashed is prefix-free encoded before hashing.
*
* Usage: 1) call tc_sha256_init to initialize a struct
* tc_sha256_state_struct before hashing a new string.
*
* 2) call tc_sha256_update to hash the next string segment;
* tc_sha256_update can be called as many times as needed to hash
* all of the segments of a string; the order is important.
*
* 3) call tc_sha256_final to out put the digest from a hashing
* operation.
*/
#ifndef __TC_SHA256_H__
#define __TC_SHA256_H__
#include <stddef.h>
#include <stdint.h>
#ifdef __cplusplus
extern "C" {
#endif
#define TC_SHA256_BLOCK_SIZE (64)
#define TC_SHA256_DIGEST_SIZE (32)
#define TC_SHA256_STATE_BLOCKS (TC_SHA256_DIGEST_SIZE/4)
struct tc_sha256_state_struct {
uint32_t iv[TC_SHA256_STATE_BLOCKS];
uint64_t bits_hashed;
uint8_t leftover[TC_SHA256_BLOCK_SIZE];
size_t leftover_offset;
};
typedef struct tc_sha256_state_struct *TCSha256State_t;
/**
* @brief SHA256 initialization procedure
* Initializes s
* @return returns TC_SUCCESS (1)
* returns TC_FAIL (0) if s == NULL
* @param s Sha256 state struct
*/
int32_t tc_sha256_init(TCSha256State_t s);
/**
* @brief SHA256 update procedure
* Hashes data_length bytes addressed by data into state s
* @return returns TC_SUCCESS (1)
* returns TC_FAIl (0) if:
* s == NULL,
* s->iv == NULL,
* data == NULL
* @note Assumes s has been initialized by tc_sha256_init
* @warning The state buffer 'leftover' is left in memory after processing
* If your application intends to have sensitive data in this
* buffer, remind to erase it after the data has been processed
* @param s Sha256 state struct
* @param data message to hash
* @param datalen length of message to hash
*/
int32_t tc_sha256_update(TCSha256State_t s,
const uint8_t *data,
size_t datalen);
/**
* @brief SHA256 final procedure
* Inserts the completed hash computation into digest
* @return returns TC_SUCCESS (1)
* returns TC_FAIL (0) if:
* s == NULL,
* s->iv == NULL,
* digest == NULL
* @note Assumes: s has been initialized by tc_sha256_init
* digest points to at least TC_SHA256_DIGEST_SIZE bytes
* @warning The state buffer 'leftover' is left in memory after processing
* If your application intends to have sensitive data in this
* buffer, remind to erase it after the data has been processed
* @param digest unsigned eight bit integer
* @param Sha256 state struct
*/
int32_t tc_sha256_final(uint8_t *digest, TCSha256State_t s);
#ifdef __cplusplus
}
#endif
#endif
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