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// Copyright 2015 The Weave Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "src/crypto_hmac.h"
#include <stddef.h>
#include <stdint.h>
#include <string.h>
#include <openssl/evp.h>
#include <openssl/hmac.h>
bool uw_crypto_hmac_(const uint8_t* key,
size_t key_len,
const UwCryptoHmacMsg messages[],
size_t num_messages,
uint8_t* truncated_digest,
size_t truncated_digest_len) {
HMAC_CTX context = {0};
HMAC_CTX_init(&context);
if (!HMAC_Init(&context, key, key_len, EVP_sha256()))
return false;
for (size_t i = 0; i < num_messages; ++i) {
if (messages[i].num_bytes &&
(!messages[i].bytes ||
!HMAC_Update(&context, messages[i].bytes, messages[i].num_bytes))) {
return false;
}
}
const size_t kFullDigestLen = (size_t)EVP_MD_size(EVP_sha256());
if (truncated_digest_len > kFullDigestLen) {
return false;
}
uint8_t digest[kFullDigestLen];
uint32_t len = kFullDigestLen;
bool result = HMAC_Final(&context, digest, &len) && kFullDigestLen == len;
HMAC_CTX_cleanup(&context);
if (result) {
memcpy(truncated_digest, digest, truncated_digest_len);
}
return result;
}
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