public PacketKexInit(byte payload[], int off, int len) throws IOException {
    this.payload = new byte[len];
    System.arraycopy(payload, off, this.payload, 0, len);

    TypesReader tr = new TypesReader(payload, off, len);

    int packet_type = tr.readByte();

    if (packet_type != Packets.SSH_MSG_KEXINIT)
      throw new IOException("This is not a KexInitPacket! (" + packet_type + ")");

    kp.cookie = tr.readBytes(16);
    kp.kex_algorithms = tr.readNameList();
    kp.server_host_key_algorithms = tr.readNameList();
    kp.encryption_algorithms_client_to_server = tr.readNameList();
    kp.encryption_algorithms_server_to_client = tr.readNameList();
    kp.mac_algorithms_client_to_server = tr.readNameList();
    kp.mac_algorithms_server_to_client = tr.readNameList();
    kp.compression_algorithms_client_to_server = tr.readNameList();
    kp.compression_algorithms_server_to_client = tr.readNameList();
    kp.languages_client_to_server = tr.readNameList();
    kp.languages_server_to_client = tr.readNameList();
    kp.first_kex_packet_follows = tr.readBoolean();
    kp.reserved_field1 = tr.readUINT32();

    if (tr.remain() != 0) throw new IOException("Padding in KexInitPacket!");
  }
  public PacketKexInit(CryptoWishList cwl, SecureRandom rnd) {
    kp.cookie = new byte[16];
    rnd.nextBytes(kp.cookie);

    kp.kex_algorithms = cwl.kexAlgorithms;
    kp.server_host_key_algorithms = cwl.serverHostKeyAlgorithms;
    kp.encryption_algorithms_client_to_server = cwl.c2s_enc_algos;
    kp.encryption_algorithms_server_to_client = cwl.s2c_enc_algos;
    kp.mac_algorithms_client_to_server = cwl.c2s_mac_algos;
    kp.mac_algorithms_server_to_client = cwl.s2c_mac_algos;
    kp.compression_algorithms_client_to_server = new String[] {"none"};
    kp.compression_algorithms_server_to_client = new String[] {"none"};
    kp.languages_client_to_server = new String[] {};
    kp.languages_server_to_client = new String[] {};
    kp.first_kex_packet_follows = false;
    kp.reserved_field1 = 0;
  }