content: /*
   * Copyright (C) 2010 The Android Open Source Project
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package com.google.android.vending.licensing;
  
  import android.content.SharedPreferences;
  import android.util.Log;
  
  /**
   * An wrapper for SharedPreferences that transparently performs data obfuscation.
   */
  public class PreferenceObfuscator {
  
      private static final String TAG = "PreferenceObfuscator";
  
      private final SharedPreferences mPreferences;
      private final Obfuscator mObfuscator;
      private SharedPreferences.Editor mEditor;
  
      /**
       * Constructor.
       *
       * @param sp A SharedPreferences instance provided by the system.
       * @param o The Obfuscator to use when reading or writing data.
       */
      public PreferenceObfuscator(SharedPreferences sp, Obfuscator o) {
          mPreferences = sp;
          mObfuscator = o;
          mEditor = null;
      }
  
      public void putString(String key, String value) {
          if (mEditor == null) {
              mEditor = mPreferences.edit();
          }
          String obfuscatedValue = mObfuscator.obfuscate(value, key);
          mEditor.putString(key, obfuscatedValue);
      }
  
      public String getString(String key, String defValue) {
          String result;
          String value = mPreferences.getString(key, null);
          if (value != null) {
              try {
                  result = mObfuscator.unobfuscate(value, key);
              } catch (ValidationException e) {
                  // Unable to unobfuscate, data corrupt or tampered
                  Log.w(TAG, "Validation error while reading preference: " + key);
                  result = defValue;
              }
          } else {
              // Preference not found
              result = defValue;
          }
          return result;
      }
  
      public void commit() {
          if (mEditor != null) {
              mEditor.commit();
              mEditor = null;
          }
      }
  }
  