1// Copyright (c) 2011 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "crypto/hmac.h"
6
7#include <openssl/hmac.h>
8#include <stddef.h>
9
10#include <algorithm>
11#include <vector>
12
13#include "base/logging.h"
14#include "base/memory/scoped_ptr.h"
15#include "base/stl_util.h"
16#include "crypto/openssl_util.h"
17
18namespace crypto {
19
20struct HMACPlatformData {
21  std::vector<unsigned char> key;
22};
23
24HMAC::HMAC(HashAlgorithm hash_alg) : hash_alg_(hash_alg) {
25  // Only SHA-1 and SHA-256 hash algorithms are supported now.
26  DCHECK(hash_alg_ == SHA1 || hash_alg_ == SHA256);
27}
28
29bool HMAC::Init(const unsigned char* key, size_t key_length) {
30  // Init must not be called more than once on the same HMAC object.
31  DCHECK(!plat_);
32  plat_.reset(new HMACPlatformData());
33  plat_->key.assign(key, key + key_length);
34  return true;
35}
36
37HMAC::~HMAC() {
38  if (plat_) {
39    // Zero out key copy.
40    plat_->key.assign(plat_->key.size(), 0);
41    STLClearObject(&plat_->key);
42  }
43}
44
45bool HMAC::Sign(const base::StringPiece& data,
46                unsigned char* digest,
47                size_t digest_length) const {
48  DCHECK(plat_);  // Init must be called before Sign.
49
50  ScopedOpenSSLSafeSizeBuffer<EVP_MAX_MD_SIZE> result(digest, digest_length);
51  return !!::HMAC(hash_alg_ == SHA1 ? EVP_sha1() : EVP_sha256(),
52                  plat_->key.data(), plat_->key.size(),
53                  reinterpret_cast<const unsigned char*>(data.data()),
54                  data.size(), result.safe_buffer(), NULL);
55}
56
57}  // namespace crypto
58