the sequence number is kept in synchronization with the current transmitter sequence number by overwriting the sequence number in memory 42 with the decrypted new sequence number importantly the present invention allows the user to easily and readily register any transmitting device 39 s randomly generated encryption key with the receiver to change the existing encryption key of any such device in such a fashion that there is no human readable record of the key and therefore no one knows the updated key thus ensuring the security of the system fig4 illustrates in detail the message format of the present invention for both unencrypted messages standard format a and encrypted messages encrypted format b with reference to encrypted format b each encrypted wireless key 2b or keypad 2a is identified by the receiver using a unique factory configured 16 bit number in n9 n12 field 30 referred to here as the device id distinguished from a wireless key serial number id or a user security code in d1 d6 that is passed on to and recognized only by the control this unique device id must be registered or 34 learned 34 by the receiver before the transmitting device can communicate its normal d1 d6 data to the control via encrypted messages to the receiver since the receiver processes multiple encrypted keys and keypads as well as unencrypted wireless devices the receiver must be able to add or delete encrypted device ids and their unique encryption keys to its internal non volatile memory 42 in order to avoid possible manipulation by technically skilled intruders the user first places the security control into a programming mode of operation which.