1 // Copyright (c) 2006-2008 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 // 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 BASE_HMAC_H_ 9 #define BASE_HMAC_H_ 10 11 #include <string> 12 13 #include "base/basictypes.h" 14 #include "base/scoped_ptr.h" 15 16 namespace base { 17 18 // Simplify the interface and reduce includes by abstracting out the internals. 19 struct HMACPlatformData; 20 21 class HMAC { 22 public: 23 // The set of supported hash functions. Extend as required. 24 enum HashAlgorithm { 25 SHA1 26 }; 27 28 explicit HMAC(HashAlgorithm hash_alg); 29 ~HMAC(); 30 31 // Initializes this instance using |key| of the length |key_length|. Call Init 32 // only once. It returns false on the second or later calls. 33 bool Init(const unsigned char* key, int key_length); 34 35 // Initializes this instance using |key|. Call Init only once. It returns 36 // false on the second or later calls. Init(const std::string & key)37 bool Init(const std::string& key) { 38 return Init(reinterpret_cast<const unsigned char*>(key.data()), 39 static_cast<int>(key.size())); 40 } 41 42 // Calculates the HMAC for the message in |data| using the algorithm supplied 43 // to the constructor and the key supplied to the Init method. The HMAC is 44 // returned in |digest|, which has |digest_length| bytes of storage available. 45 bool Sign(const std::string& data, unsigned char* digest, int digest_length); 46 47 private: 48 HashAlgorithm hash_alg_; 49 scoped_ptr<HMACPlatformData> plat_; 50 51 DISALLOW_COPY_AND_ASSIGN(HMAC); 52 }; 53 54 } // namespace base 55 56 #endif // BASE_HMAC_H_ 57