126 lines
5.1 KiB
C
126 lines
5.1 KiB
C
/* hmac.h - TinyCrypt interface to an HMAC implementation */
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/*
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* Copyright (C) 2015 by Intel Corporation, All Rights Reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* - Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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*
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* - Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* - Neither the name of Intel Corporation nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/**
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* @file
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* @brief Interface to an HMAC implementation.
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*
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* Overview: HMAC is a message authentication code based on hash functions.
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* TinyCrypt hard codes SHA-256 as the hash function. A message
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* authentication code based on hash functions is also called a
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* keyed cryptographic hash function since it performs a
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* transformation specified by a key in an arbitrary length data
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* set into a fixed length data set (also called tag).
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*
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* Security: The security of the HMAC depends on the length of the key and
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* on the security of the hash function. Note that HMAC primitives
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* are much less affected by collision attacks than their
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* corresponding hash functions.
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*
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* Requires: SHA-256
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*
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* Usage: 1) call tc_hmac_set_key to set the HMAC key.
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*
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* 2) call tc_hmac_init to initialize a struct hash_state before
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* processing the data.
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*
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* 3) call tc_hmac_update to process the next input segment;
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* tc_hmac_update can be called as many times as needed to process
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* all of the segments of the input; the order is important.
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*
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* 4) call tc_hmac_final to out put the tag.
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*/
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#ifndef __TC_HMAC_H__
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#define __TC_HMAC_H__
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#include <sha256.h>
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struct tc_hmac_state_struct {
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struct tc_sha256_state_struct hash_state; /* the internal state required by h */
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uint8_t key[2*TC_SHA256_BLOCK_SIZE]; /* HMAC key schedule */
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};
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typedef struct tc_hmac_state_struct *TCHmacState_t;
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/**
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* @brief HMAC set key procedure
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* Configures ctx to use key
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* @return returns TC_SUCCESS (1)
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* returns TC_FAIL (0) if
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* ctx == NULL or
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* key == NULL or
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* key_size == 0
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* @param ctx IN/OUT -- the struct tc_hmac_state_struct to initial
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* @param key IN -- the HMAC key to configure
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* @param key_size IN -- the HMAC key size
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*/
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int32_t tc_hmac_set_key(TCHmacState_t ctx, const uint8_t *key, uint32_t key_size);
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/**
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* @brief HMAC init procedure
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* Initializes ctx to begin the next HMAC operation
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* @return returns TC_SUCCESS (1)
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* returns TC_FAIL (0) if: ctx == NULL or key == NULL
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* @param ctx IN/OUT -- struct tc_hmac_state_struct buffer to init
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*/
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int32_t tc_hmac_init(TCHmacState_t ctx);
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/**
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* @brief HMAC update procedure
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* Mixes data_length bytes addressed by data into state
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* @return returns TC_SUCCCESS (1)
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* returns TC_FAIL (0) if: ctx == NULL or key == NULL
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* @note Assumes state has been initialized by tc_hmac_init
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* @param ctx IN/OUT -- state of HMAC computation so far
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* @param data IN -- data to incorporate into state
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* @param data_length IN -- size of data in bytes
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*/
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int32_t tc_hmac_update(TCHmacState_t ctx, const void *data, uint32_t data_length);
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/**
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* @brief HMAC final procedure
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* Writes the HMAC tag into the tag buffer
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* @return returns TC_SUCCESS (1)
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* returns TC_FAIL (0) if:
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* tag == NULL or
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* ctx == NULL or
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* key == NULL or
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* taglen != TC_SHA256_DIGEST_SIZE
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* @note Assumes the tag bufer is at least sizeof(hmac_tag_size(state)) bytes
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* state has been initialized by tc_hmac_init
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* @param tag IN/OUT -- buffer to receive computed HMAC tag
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* @param taglen IN -- size of tag in bytes
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* @param ctx IN -- the HMAC state for computing tag
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*/
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int32_t tc_hmac_final(uint8_t *tag, uint32_t taglen, TCHmacState_t ctx);
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#endif
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