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 <CommonCrypto/CommonHMAC.h>
8
9#include "base/logging.h"
10
11namespace crypto {
12
13struct HMACPlatformData {
14  std::string key_;
15};
16
17HMAC::HMAC(HashAlgorithm hash_alg)
18    : hash_alg_(hash_alg), plat_(new HMACPlatformData()) {
19  // Only SHA-1 and SHA-256 hash algorithms are supported now.
20  DCHECK(hash_alg_ == SHA1 || hash_alg_ == SHA256);
21}
22
23bool HMAC::Init(const unsigned char *key, int key_length) {
24  if (!plat_->key_.empty()) {
25    // Init must not be called more than once on the same HMAC object.
26    NOTREACHED();
27    return false;
28  }
29
30  plat_->key_.assign(reinterpret_cast<const char*>(key), key_length);
31
32  return true;
33}
34
35HMAC::~HMAC() {
36  // Zero out key copy.
37  plat_->key_.assign(plat_->key_.length(), std::string::value_type());
38  plat_->key_.clear();
39  plat_->key_.reserve(0);
40}
41
42bool HMAC::Sign(const std::string& data,
43                unsigned char* digest,
44                int digest_length) {
45  CCHmacAlgorithm algorithm;
46  int algorithm_digest_length;
47  switch (hash_alg_) {
48    case SHA1:
49      algorithm = kCCHmacAlgSHA1;
50      algorithm_digest_length = CC_SHA1_DIGEST_LENGTH;
51      break;
52    case SHA256:
53      algorithm = kCCHmacAlgSHA256;
54      algorithm_digest_length = CC_SHA256_DIGEST_LENGTH;
55      break;
56    default:
57      NOTREACHED();
58      return false;
59  }
60
61  if (digest_length < algorithm_digest_length) {
62    NOTREACHED();
63    return false;
64  }
65
66  CCHmac(algorithm,
67         plat_->key_.data(), plat_->key_.length(), data.data(), data.length(),
68         digest);
69
70  return true;
71}
72
73}  // namespace crypto
74