/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you 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 org.apache.hadoop.hbase.io.crypto.aes;
  
  import java.io.InputStream;
  import java.security.InvalidAlgorithmParameterException;
  import java.security.InvalidKeyException;
  import java.security.Key;
  
  import javax.crypto.spec.IvParameterSpec;
  
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.classification.InterfaceStability;
  import org.apache.hadoop.hbase.io.crypto.Decryptor;
  
  import com.google.common.base.Preconditions;
  
  @InterfaceAudience.Private
  @InterfaceStability.Evolving
  public class AESDecryptor implements Decryptor {
  
    private javax.crypto.Cipher cipher;
    private Key key;
    private byte[] iv;
    private boolean initialized = false;
  
    public AESDecryptor(javax.crypto.Cipher cipher) {
      this.cipher = cipher;
    }
  
    javax.crypto.Cipher getCipher() {
      return cipher;
    }
  
    @Override
    public void setKey(Key key) {
      Preconditions.checkNotNull(key, "Key cannot be null");
      this.key = key;
    }
  
    @Override
    public int getIvLength() {
      return AES.IV_LENGTH;
    }
  
    @Override
    public int getBlockSize() {
      return AES.BLOCK_SIZE;
    }
  
    @Override
    public void setIv(byte[] iv) {
      Preconditions.checkNotNull(iv, "IV cannot be null");
      Preconditions.checkArgument(iv.length == AES.IV_LENGTH, "Invalid IV length");
      this.iv = iv;
    }
  
    @Override
    public InputStream createDecryptionStream(InputStream in) {
      if (!initialized) {
        init();
      }
      return new javax.crypto.CipherInputStream(in, cipher);
    }
  
    @Override
    public void reset() {
      init();
    }
  
    protected void init() {
      try {
        if (iv == null) {
          throw new NullPointerException("IV is null");
        }
        cipher.init(javax.crypto.Cipher.DECRYPT_MODE, key, new IvParameterSpec(iv));
      } catch (InvalidKeyException e) {
        throw new RuntimeException(e);
      } catch (InvalidAlgorithmParameterException e) {
        throw new RuntimeException(e);
      }
      initialized = true;
    }
  
 }