ESP-IDF
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Outline
#include <tinycrypt/hmac.h>
#include <tinycrypt/constants.h>
#include <tinycrypt/utils.h>
rekey(uint8_t *, const uint8_t *, unsigned int)
tc_hmac_set_key(TCHmacState_t, const uint8_t *, unsigned int)
tc_hmac_init(TCHmacState_t)
tc_hmac_update(TCHmacState_t, const void *, unsigned int)
tc_hmac_final(uint8_t *, unsigned int, TCHmacState_t)
Files
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SourceVuESP-IDF Framework and ExamplesESP-IDFcomponents/bt/esp_ble_mesh/common/tinycrypt/src/hmac.c
 
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/* hmac.c - TinyCrypt implementation of the HMAC algorithm */ /* * Copyright (C) 2017 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. *//* ... */ #include <tinycrypt/hmac.h> #include <tinycrypt/constants.h> #include <tinycrypt/utils.h> static void rekey(uint8_t *key, const uint8_t *new_key, unsigned int key_size) { const uint8_t inner_pad = (uint8_t) 0x36; const uint8_t outer_pad = (uint8_t) 0x5c; unsigned int i; for (i = 0; i < key_size; ++i) { key[i] = inner_pad ^ new_key[i]; key[i + TC_SHA256_BLOCK_SIZE] = outer_pad ^ new_key[i]; }{...} for (; i < TC_SHA256_BLOCK_SIZE; ++i) { key[i] = inner_pad; key[i + TC_SHA256_BLOCK_SIZE] = outer_pad; }{...} }{ ... } int tc_hmac_set_key(TCHmacState_t ctx, const uint8_t *key, unsigned int key_size) { /* Input sanity check */ if (ctx == (TCHmacState_t) 0 || key == (const uint8_t *) 0 || key_size == 0) { return TC_CRYPTO_FAIL; }{...} const uint8_t dummy_key[TC_SHA256_BLOCK_SIZE]; struct tc_hmac_state_struct dummy_state; if (key_size <= TC_SHA256_BLOCK_SIZE) { /* * The next three calls are dummy calls just to avoid * certain timing attacks. Without these dummy calls, * adversaries would be able to learn whether the key_size is * greater than TC_SHA256_BLOCK_SIZE by measuring the time * consumed in this process. *//* ... */ (void)tc_sha256_init(&dummy_state.hash_state); (void)tc_sha256_update(&dummy_state.hash_state, dummy_key, key_size); (void)tc_sha256_final(&dummy_state.key[TC_SHA256_DIGEST_SIZE], &dummy_state.hash_state); /* Actual code for when key_size <= TC_SHA256_BLOCK_SIZE: */ rekey(ctx->key, key, key_size); }{...} else { (void)tc_sha256_init(&ctx->hash_state); (void)tc_sha256_update(&ctx->hash_state, key, key_size); (void)tc_sha256_final(&ctx->key[TC_SHA256_DIGEST_SIZE], &ctx->hash_state); rekey(ctx->key, &ctx->key[TC_SHA256_DIGEST_SIZE], TC_SHA256_DIGEST_SIZE); }{...} return TC_CRYPTO_SUCCESS; }{ ... } int tc_hmac_init(TCHmacState_t ctx) { /* input sanity check: */ if (ctx == (TCHmacState_t) 0) { return TC_CRYPTO_FAIL; }{...} (void) tc_sha256_init(&ctx->hash_state); (void) tc_sha256_update(&ctx->hash_state, ctx->key, TC_SHA256_BLOCK_SIZE); return TC_CRYPTO_SUCCESS; }{ ... } int tc_hmac_update(TCHmacState_t ctx, const void *data, unsigned int data_length) { /* input sanity check: */ if (ctx == (TCHmacState_t) 0) { return TC_CRYPTO_FAIL; }{...} (void)tc_sha256_update(&ctx->hash_state, data, data_length); return TC_CRYPTO_SUCCESS; }{ ... } int tc_hmac_final(uint8_t *tag, unsigned int taglen, TCHmacState_t ctx) { /* input sanity check: */ if (tag == (uint8_t *) 0 || taglen != TC_SHA256_DIGEST_SIZE || ctx == (TCHmacState_t) 0) { return TC_CRYPTO_FAIL; }{...} (void) tc_sha256_final(tag, &ctx->hash_state); (void)tc_sha256_init(&ctx->hash_state); (void)tc_sha256_update(&ctx->hash_state, &ctx->key[TC_SHA256_BLOCK_SIZE], TC_SHA256_BLOCK_SIZE); (void)tc_sha256_update(&ctx->hash_state, tag, TC_SHA256_DIGEST_SIZE); (void)tc_sha256_final(tag, &ctx->hash_state); /* destroy the current state */ _set(ctx, 0, sizeof(*ctx)); return TC_CRYPTO_SUCCESS; }{ ... }
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