HMAC-SHA1 implementation for Mac based on CommonCrypto

base/hmac.h

 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
-//
+
 // Utility class for calculating the HMAC for a given message. We currently
 // only support SHA1 for the hash algorithm, but this can be extended easily.
 
-#ifndef BASE_HMAC_H__
-#define BASE_HMAC_H__
+#ifndef BASE_HMAC_H_
+#define BASE_HMAC_H_
 
+#include "build/build_config.h"
+
+#if defined(OS_WIN)
 #include <windows.h>
 #include <wincrypt.h>
+#endif
 
 #include <string>
 
 #include "base/basictypes.h"
 
+namespace base {
+
 class HMAC {
  public:
   // The set of supported hash functions. Extend as required.
   enum HashAlgorithm {
     SHA1
   };
 
   HMAC(HashAlgorithm hash_alg, const unsigned char* key, int key_length);
   ~HMAC();
 
-  // Returns the HMAC in 'digest' for the message in 'data' and the key
-  // specified in the contructor.
+  // Calculates the HMAC for the message in |data| using the algorithm and key
+  // supplied to the constructor.  The HMAC is returned in |digest|, which
+  // has |digest_length| bytes of storage available.
   bool Sign(const std::string& data, unsigned char* digest, int digest_length);
 
  private:
+#if defined(OS_POSIX)
+  HashAlgorithm hash_alg_;
+  std::string key_;
+#elif defined(OS_WIN)
   // Import the key so that we don't have to store it ourself.
-  // TODO(paulg): Bug: http://b/1084719, 'ImportKey' will not currently work on
-  //              Windows 2000 since it requires special handling for importing
-  //              keys. See this link for details:
-  // http://www.derkeiler.com/Newsgroups/microsoft.public.platformsdk.security/2004-06/0270.html
   void ImportKey(const unsigned char* key, int key_length);
 
   // Returns the SHA1 hash of 'data' and 'key' in 'digest'. If there was any
   // error in the calculation, this method returns false, otherwise true.
   bool SignWithSHA1(const std::string& data,
                     unsigned char* digest,
                     int digest_length);
 
-  // Required for the SHA1 key_blob struct. We limit this to 16 bytes since
-  // Windows 2000 doesn't support keys larger than that.
-  static const int kMaxKeySize = 16;
-
   // The hash algorithm to use.
   HashAlgorithm hash_alg_;
 
   // Windows Crypt API resources.
   HCRYPTPROV provider_;
   HCRYPTHASH hash_;
   HCRYPTKEY hkey_;
+#endif  // OS_WIN
 
-  DISALLOW_EVIL_CONSTRUCTORS(HMAC);
+  DISALLOW_COPY_AND_ASSIGN(HMAC);
 };
 
+}  // namespace base
 
-#endif  // BASE_HMAC_H__
-
+#endif  // BASE_HMAC_H_