michael@0: // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
michael@0: // Use of this source code is governed by a BSD-style license that can be
michael@0: // found in the LICENSE file.
michael@0: 
michael@0: // Utility class for calculating the HMAC for a given message. We currently
michael@0: // only support SHA1 for the hash algorithm, but this can be extended easily.
michael@0: 
michael@0: #ifndef BASE_HMAC_H_
michael@0: #define BASE_HMAC_H_
michael@0: 
michael@0: #include <string>
michael@0: 
michael@0: #include "base/basictypes.h"
michael@0: #include "base/scoped_ptr.h"
michael@0: 
michael@0: namespace base {
michael@0: 
michael@0: // Simplify the interface and reduce includes by abstracting out the internals.
michael@0: struct HMACPlatformData;
michael@0: 
michael@0: class HMAC {
michael@0:  public:
michael@0:   // The set of supported hash functions. Extend as required.
michael@0:   enum HashAlgorithm {
michael@0:     SHA1
michael@0:   };
michael@0: 
michael@0:   explicit HMAC(HashAlgorithm hash_alg);
michael@0:   ~HMAC();
michael@0: 
michael@0:   // Initializes this instance using |key| of the length |key_length|. Call Init
michael@0:   // only once. It returns false on the second or later calls.
michael@0:   bool Init(const unsigned char* key, int key_length);
michael@0: 
michael@0:   // Initializes this instance using |key|. Call Init only once. It returns
michael@0:   // false on the second or later calls.
michael@0:   bool Init(const std::string& key) {
michael@0:     return Init(reinterpret_cast<const unsigned char*>(key.data()),
michael@0:                 static_cast<int>(key.size()));
michael@0:   }
michael@0: 
michael@0:   // Calculates the HMAC for the message in |data| using the algorithm supplied
michael@0:   // to the constructor and the key supplied to the Init method. The HMAC is
michael@0:   // returned in |digest|, which has |digest_length| bytes of storage available.
michael@0:   bool Sign(const std::string& data, unsigned char* digest, int digest_length);
michael@0: 
michael@0:  private:
michael@0:   HashAlgorithm hash_alg_;
michael@0:   scoped_ptr<HMACPlatformData> plat_;
michael@0: 
michael@0:   DISALLOW_COPY_AND_ASSIGN(HMAC);
michael@0: };
michael@0: 
michael@0: }  // namespace base
michael@0: 
michael@0: #endif  // BASE_HMAC_H_