'Check if the Dot11 packet is a valid EAPOL KEY frame
:param self: Handshakeverify object
:param packet: A scapy.layers.RadioTap object
:type self: Handshakeverify
:type packet: scapy.layers.RadioTap
:return True if this is an EAPOL KEY frame
:rtype: bool'

@staticmethod
def is_valid_handshake_frame(packet):

    if (packet.haslayer(dot11.Dot11) and (not (packet.FCfield & (1 << 3)))):
        if (packet.haslayer(dot11.EAPOL) and (packet[dot11.EAPOL].type == 3)):
            return True
    return False
