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| 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 // Utility class for calculating the HMAC for a given message. We currently |
| 6 // only support SHA1 for the hash algorithm, but this can be extended easily. |
| 7 |
| 8 #ifndef CRYPTO_HMAC_H_ |
| 9 #define CRYPTO_HMAC_H_ |
| 10 #pragma once |
| 11 |
| 12 #include <string> |
| 13 |
| 14 #include "base/basictypes.h" |
| 15 #include "base/memory/scoped_ptr.h" |
| 16 |
| 17 namespace crypto { |
| 18 |
| 19 // Simplify the interface and reduce includes by abstracting out the internals. |
| 20 struct HMACPlatformData; |
| 21 |
| 22 class HMAC { |
| 23 public: |
| 24 // The set of supported hash functions. Extend as required. |
| 25 enum HashAlgorithm { |
| 26 SHA1, |
| 27 SHA256, |
| 28 }; |
| 29 |
| 30 explicit HMAC(HashAlgorithm hash_alg); |
| 31 ~HMAC(); |
| 32 |
| 33 // Initializes this instance using |key| of the length |key_length|. Call Init |
| 34 // only once. It returns false on the second or later calls. |
| 35 bool Init(const unsigned char* key, int key_length); |
| 36 |
| 37 // Initializes this instance using |key|. Call Init only once. It returns |
| 38 // false on the second or later calls. |
| 39 bool Init(const std::string& key) { |
| 40 return Init(reinterpret_cast<const unsigned char*>(key.data()), |
| 41 static_cast<int>(key.size())); |
| 42 } |
| 43 |
| 44 // Calculates the HMAC for the message in |data| using the algorithm supplied |
| 45 // to the constructor and the key supplied to the Init method. The HMAC is |
| 46 // returned in |digest|, which has |digest_length| bytes of storage available. |
| 47 bool Sign(const std::string& data, unsigned char* digest, int digest_length); |
| 48 |
| 49 // TODO(albertb): Add a Verify method. |
| 50 |
| 51 private: |
| 52 HashAlgorithm hash_alg_; |
| 53 scoped_ptr<HMACPlatformData> plat_; |
| 54 |
| 55 DISALLOW_COPY_AND_ASSIGN(HMAC); |
| 56 }; |
| 57 |
| 58 } // namespace crypto |
| 59 |
| 60 #endif // CRYPTO_HMAC_H_ |
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