def METHOD_NAME(self, stream, header):
    """
    Decode a security exchange PDU.
    :type stream: BytesIO
    :type header: int
    :return: RDPSecurityExchangePDU
    """
    length = Uint32LE.unpack(stream)
    clientRandom = stream.read(length)
    return SecurityExchangePDU(header, clientRandom)