content: /*
   * Copyright (C) 2018 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.android.ike.ikev2.message;
  
  import com.android.ike.ikev2.exceptions.IkeException;
  
  import java.nio.ByteBuffer;
  import java.security.GeneralSecurityException;
  
  import javax.crypto.Cipher;
  import javax.crypto.Mac;
  import javax.crypto.SecretKey;
  
  /**
   * IkeSkPayload represents a Encrypted Payload.
   *
   * <p>It contains other payloads in encrypted form. It is must be the last payload in the message.
   * It should be the only payload in this implementation.
   *
   * <p>Critical bit must be ignored when doing decoding.
   *
   * @see <a href="https://tools.ietf.org/html/rfc7296#page-105">RFC 7296, Internet Key Exchange
   *     Protocol Version 2 (IKEv2)</a>
   */
  public final class IkeSkPayload extends IkePayload {
  
      private final IkeEncryptedPayloadBody mIkeEncryptedPayloadBody;
  
      /**
       * Construct an instance of IkeSkPayload from decrypting an incoming packet.
       *
       * @param critical indicates if it is a critical payload.
       * @param message the byte array contains the whole IKE message.
       * @param integrityMac the initialized Mac for integrity check.
       * @param checksumLen the checksum length of negotiated integrity algorithm.
       * @param decryptCipher the uninitialized Cipher for doing decryption.
       * @param dKey the decryption key.
       */
      IkeSkPayload(
              boolean critical,
              byte[] message,
              Mac integrityMac,
              int checksumLen,
              Cipher decryptCipher,
              SecretKey dKey)
              throws IkeException, GeneralSecurityException {
          super(PAYLOAD_TYPE_SK, critical);
  
          mIkeEncryptedPayloadBody =
                  new IkeEncryptedPayloadBody(
                          message, integrityMac, checksumLen, decryptCipher, dKey);
      }
  
      /**
       * Construct an instance of IkeSkPayload for building outbound packet.
       *
       * @param ikeHeader the IKE header.
       * @param firstPayloadType the type of first payload nested in SkPayload.
       * @param unencryptedPayloads the encoded payload list to protect.
       * @param integrityMac the initialized Mac for calculating integrity checksum
       * @param checksumLen the checksum length of negotiated integrity algorithm.
       * @param encryptCipher the uninitialized Cipher for doing encryption.
       * @param eKey the encryption key.
       */
      IkeSkPayload(
              IkeHeader ikeHeader,
              @PayloadType int firstPayloadType,
              byte[] unencryptedPayloads,
              Mac integrityMac,
              int checksumLen,
              Cipher encryptCipher,
              SecretKey eKey) {
          super(PAYLOAD_TYPE_SK, false);
  
          mIkeEncryptedPayloadBody =
                  new IkeEncryptedPayloadBody(
                          ikeHeader,
                          firstPayloadType,
                          unencryptedPayloads,
                          integrityMac,
                          checksumLen,
                          encryptCipher,
                          eKey);
      }
  
      /**
       * Return unencrypted payload list
       *
       * @return unencrypted payload list in a byte array.
       */
      public byte[] getUnencryptedPayloads() {
          return mIkeEncryptedPayloadBody.getUnencryptedData();
      }
  
      // TODO: Add another constructor for AEAD protected payload.
  
      /**
       * Encode this payload to a ByteBuffer.
       *
       * @param nextPayload type of payload that follows this payload.
       * @param byteBuffer destination ByteBuffer that stores encoded payload.
       */
      @Override
      protected void encodeToByteBuffer(@PayloadType int nextPayload, ByteBuffer byteBuffer) {
          encodePayloadHeaderToByteBuffer(nextPayload, getPayloadLength(), byteBuffer);
          byteBuffer.put(mIkeEncryptedPayloadBody.encode());
      }
  
      /**
       * Get entire payload length.
       *
       * @return entire payload length.
       */
      @Override
      protected int getPayloadLength() {
          return GENERIC_HEADER_LENGTH + mIkeEncryptedPayloadBody.getLength();
      }
  
      /**
       * Return the payload type as a String.
       *
       * @return the payload type as a String.
       */
      @Override
      public String getTypeString() {
          return "Encrypted and Authenticated Payload";
      }
  }
  