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// Copyright (c) 2011 The Chromium 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 "crypto/hmac.h"
#include <CommonCrypto/CommonHMAC.h>
#include "base/logging.h"
namespace crypto {
struct HMACPlatformData {
std::string key_;
};
HMAC::HMAC(HashAlgorithm hash_alg)
: hash_alg_(hash_alg), plat_(new HMACPlatformData()) {
// Only SHA-1 and SHA-256 hash algorithms are supported now.
DCHECK(hash_alg_ == SHA1 || hash_alg_ == SHA256);
}
bool HMAC::Init(const unsigned char *key, int key_length) {
if (!plat_->key_.empty()) {
// Init must not be called more than once on the same HMAC object.
NOTREACHED();
return false;
}
plat_->key_.assign(reinterpret_cast<const char*>(key), key_length);
return true;
}
HMAC::~HMAC() {
// Zero out key copy.
plat_->key_.assign(plat_->key_.length(), std::string::value_type());
plat_->key_.clear();
plat_->key_.reserve(0);
}
bool HMAC::Sign(const std::string& data,
unsigned char* digest,
int digest_length) {
CCHmacAlgorithm algorithm;
int algorithm_digest_length;
switch (hash_alg_) {
case SHA1:
algorithm = kCCHmacAlgSHA1;
algorithm_digest_length = CC_SHA1_DIGEST_LENGTH;
break;
case SHA256:
algorithm = kCCHmacAlgSHA256;
algorithm_digest_length = CC_SHA256_DIGEST_LENGTH;
break;
default:
NOTREACHED();
return false;
}
if (digest_length < algorithm_digest_length) {
NOTREACHED();
return false;
}
CCHmac(algorithm,
plat_->key_.data(), plat_->key_.length(), data.data(), data.length(),
digest);
return true;
}
} // namespace crypto
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