content: package act.crypto;
  
  /*-
   * #%L
   * ACT Framework
   * %%
   * Copyright (C) 2014 - 2018 ActFramework
   * %%
   * 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.
   * #L%
   */
  
  import act.session.RotationSecretProvider;
  import org.osgl.$;
  
  import javax.crypto.Mac;
  
  public class RotateSecretHMAC extends HMAC {
  
      private RotationSecretProvider secretProvider;
      private boolean rotateEnabled;
  
      public RotateSecretHMAC(String algoKey, RotationSecretProvider secretProvider) {
          super(secretProvider.rawSecret(), algoKey);
          this.secretProvider = $.requireNotNull(secretProvider);
          this.rotateEnabled = secretProvider.isRotateEnabled();
      }
  
      public RotateSecretHMAC(Algorithm algo, RotationSecretProvider secretProvider) {
          super(secretProvider.rawSecret(), algo);
          this.secretProvider = secretProvider;
      }
  
      @Override
      protected boolean verifyHash(byte[] payload, byte[] hash) {
          if (!rotateEnabled) {
              return super.verifyHash(payload, hash);
          }
          return verifyHash(payload, hash, curMac())
                  || verifyHash(payload, hash, prevMac())
                  || verifyHash(payload, hash, nextMac());
      }
  
      @Override
      protected byte[] doHash(byte[] bytes) {
          return rotateEnabled ? doHash(bytes, curMac()) : super.doHash(bytes);
      }
  
      private Mac curMac() {
          return algo.macOf(secretProvider.curSecret());
      }
  
      private Mac prevMac() {
          return algo.macOf(secretProvider.lastSecret());
      }
  
      private Mac nextMac() {
          return algo.macOf(secretProvider.nextSecret());
      }
  }
  