content: /**
   * Copyright (C) 2014-2016 Open Whisper Systems
   *
   * Licensed according to the LICENSE file in this repository.
   */
  
  package org.whispersystems.libsignal.groups.ratchet;
  
  import org.whispersystems.libsignal.kdf.HKDFv3;
  import org.whispersystems.libsignal.util.ByteUtil;
  
  /**
   * The final symmetric material (IV and Cipher Key) used for encrypting
   * individual SenderKey messages.
   *
   * @author Moxie Marlinspike
   */
  public class SenderMessageKey {
  
    private final int    iteration;
    private final byte[] iv;
    private final byte[] cipherKey;
    private final byte[] seed;
  
    public SenderMessageKey(int iteration, byte[] seed) {
      byte[] derivative = new HKDFv3().deriveSecrets(seed, "WhisperGroup".getBytes(), 48);
      byte[][] parts    = ByteUtil.split(derivative, 16, 32);
  
      this.iteration = iteration;
      this.seed      = seed;
      this.iv        = parts[0];
      this.cipherKey = parts[1];
    }
  
    public int getIteration() {
      return iteration;
    }
  
    public byte[] getIv() {
      return iv;
    }
  
    public byte[] getCipherKey() {
      return cipherKey;
    }
  
    public byte[] getSeed() {
      return seed;
    }
  }
  