1 // Copyright (c) 2008 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 "base/hmac.h"
6
7 #include <CommonCrypto/CommonHMAC.h>
8
9 #include "base/logging.h"
10
11 namespace base {
12
13 struct HMACPlatformData {
14 std::string key_;
15 };
16
HMAC(HashAlgorithm hash_alg)17 HMAC::HMAC(HashAlgorithm hash_alg)
18 : hash_alg_(hash_alg), plat_(new HMACPlatformData()) {
19 // Only SHA-1 digest is supported now.
20 DCHECK(hash_alg_ == SHA1);
21 }
22
Init(const unsigned char * key,int key_length)23 bool 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
~HMAC()35 HMAC::~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
Sign(const std::string & data,unsigned char * digest,int digest_length)42 bool 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 default:
53 NOTREACHED();
54 return false;
55 }
56
57 if (digest_length < algorithm_digest_length) {
58 NOTREACHED();
59 return false;
60 }
61
62 CCHmac(algorithm,
63 plat_->key_.data(), plat_->key_.length(), data.data(), data.length(),
64 digest);
65
66 return true;
67 }
68
69 } // namespace base
70