| // Copyright 2013 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. |
| |
| #ifndef CHROME_BROWSER_PREFS_PREF_HASH_CALCULATOR_H_ |
| #define CHROME_BROWSER_PREFS_PREF_HASH_CALCULATOR_H_ |
| |
| #include <string> |
| |
| #include "base/basictypes.h" |
| #include "base/callback.h" |
| #include "base/memory/scoped_ptr.h" |
| |
| namespace base { |
| class Value; |
| } // namespace base |
| |
| // Calculates and validates preference value hashes. |
| class PrefHashCalculator { |
| public: |
| enum ValidationResult { |
| INVALID, |
| VALID, |
| // Valid under a deprecated but as secure algorithm. |
| VALID_SECURE_LEGACY, |
| // Valid under a deprecated and less secure algorithm. |
| VALID_WEAK_LEGACY, |
| }; |
| |
| typedef base::Callback<std::string(const std::string& modern_device_id)> |
| GetLegacyDeviceIdCallback; |
| |
| // Constructs a PrefHashCalculator using |seed| and |device_id|. The same |
| // parameters must be used in order to successfully validate generated hashes. |
| // |device_id| may be empty. |
| PrefHashCalculator(const std::string& seed, const std::string& device_id); |
| |
| // Same as the constructor above, but also specifies that |
| // |get_legacy_device_id_callback| should be used rather than the default to |
| // obtain the legacy device id if required. |
| PrefHashCalculator( |
| const std::string& seed, |
| const std::string& device_id, |
| const GetLegacyDeviceIdCallback& get_legacy_device_id_callback); |
| |
| ~PrefHashCalculator(); |
| |
| // Calculates a hash value for the supplied preference |path| and |value|. |
| // |value| may be null if the preference has no value. |
| std::string Calculate(const std::string& path, const base::Value* value) |
| const; |
| |
| // Validates the provided preference hash using current and legacy hashing |
| // algorithms. |
| ValidationResult Validate(const std::string& path, |
| const base::Value* value, |
| const std::string& hash) const; |
| |
| private: |
| // Returns the legacy device id based off of |raw_device_id_|. This method |
| // lazily gets the legacy device id via |get_legacy_device_id_callback_| and |
| // caches the result in |legacy_device_id_instance_| for future retrievals. |
| std::string RetrieveLegacyDeviceId() const; |
| |
| const std::string seed_; |
| const std::string device_id_; |
| |
| // The raw device id from which the legacy device id will be derived if |
| // required. |
| const std::string raw_device_id_; |
| |
| const GetLegacyDeviceIdCallback get_legacy_device_id_callback_; |
| |
| // A cache for the legacy device id which is hard to compute and thus lazily |
| // computed when/if required (computing the original value for this instance |
| // is allowed in const methods). |
| mutable scoped_ptr<const std::string> legacy_device_id_instance_; |
| |
| DISALLOW_COPY_AND_ASSIGN(PrefHashCalculator); |
| }; |
| |
| #endif // CHROME_BROWSER_PREFS_PREF_HASH_CALCULATOR_H_ |