components/user_prefs/tracked/pref_hash_calculator.h

   1 // Copyright 2013 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 #ifndef COMPONENTS_USER_PREFS_TRACKED_PREF_HASH_CALCULATOR_H_
   6 #define COMPONENTS_USER_PREFS_TRACKED_PREF_HASH_CALCULATOR_H_
   7
   8 #include <string>
   9
  10 #include "base/basictypes.h"
  11
  12 namespace base {
  13 class Value;
  14 }  // namespace base
  15
  16 // Calculates and validates preference value hashes.
  17 class PrefHashCalculator {
  18  public:
  19   enum ValidationResult {
  20     INVALID,
  21     VALID,
  22     // Valid under a deprecated but as secure algorithm.
  23     VALID_SECURE_LEGACY,
  24   };
  25
  26   // Constructs a PrefHashCalculator using |seed| and |device_id|. The same
  27   // parameters must be used in order to successfully validate generated hashes.
  28   // |device_id| may be empty.
  29   PrefHashCalculator(const std::string& seed, const std::string& device_id);
  30
  31   ~PrefHashCalculator();
  32
  33   // Calculates a hash value for the supplied preference |path| and |value|.
  34   // |value| may be null if the preference has no value.
  35   std::string Calculate(const std::string& path,
  36                         const base::Value* value) const;
  37
  38   // Validates the provided preference hash using current and legacy hashing
  39   // algorithms.
  40   ValidationResult Validate(const std::string& path,
  41                             const base::Value* value,
  42                             const std::string& hash) const;
  43
  44  private:
  45   const std::string seed_;
  46   const std::string device_id_;
  47   const std::string legacy_device_id_;
  48
  49   DISALLOW_COPY_AND_ASSIGN(PrefHashCalculator);
  50 };
  51
  52 #endif  // COMPONENTS_USER_PREFS_TRACKED_PREF_HASH_CALCULATOR_H_