Authorization code lockout mechanism for preventing unauthorized

Abstract

A system and method for using two simple transactions to enable the disconnection of unauthorized receiver terminals. This is accomplished in accordance with the invention by sending an addressed transaction to every known valid receiver terminal giving each one the current authorization code. After this command has been sent several times to each valid receiver terminal, a global transaction is sent to all terminals containing the current and previous authorization codes. If any receiver terminal receiving this transaction does not find a match between its stored authorization code and either of the transmitted authorization codes, it will deauthorize itself. Once into the transmission cycle, the current authorization code will become the previous authorization code and a new authorization code will be generated. The global command will be sent periodically while all the valid receiver terminals are updated with the new authorization code. Since the global command is constantly sent for checking the receiver terminals to see if they are valid and disconnecting unauthorized receiver terminals, it is not necessary in accordance with the invention to provide a send authorization phase and a check authorization phase for purposes of disconnecting unauthorized receiver terminals as in the prior art.