encrypt a MACsec frame for this Secure Association

def encrypt(self, orig_pkt, assoclen=None):
        """encrypt a MACsec frame for this Secure Association"""
        hdr = copy.deepcopy(orig_pkt)
        del hdr[MACsec].payload
        del hdr[MACsec].type
        pktlen = len(orig_pkt)
        if self.send_sci:
            hdrlen = NOSCI_LEN + SCI_LEN
        else:
            hdrlen = NOSCI_LEN
        if assoclen is None or not self.do_encrypt:
            if self.do_encrypt:
                assoclen = hdrlen
            else:
                assoclen = pktlen
        iv = self.make_iv(orig_pkt)
        assoc, pt, _ = MACsecSA.split_pkt(orig_pkt, assoclen)
        encryptor = Cipher(
            algorithms.AES(self.key),
            modes.GCM(iv),
            backend=default_backend()
        ).encryptor()
        encryptor.authenticate_additional_data(assoc)
        ct = encryptor.update(pt) + encryptor.finalize()
        hdr[MACsec].payload = Raw(assoc[hdrlen:assoclen] + ct + encryptor.tag)
        return hdr