METHOD FOR AUTHENTICATION AND PROTECTION OF SUBSCRIBERS IN TELECOMMUNICATION SYSTEMS

摘要

Radio frequency based cellular telecommunication systems often require a subscriber (10) to maintain a proprietary identifier (19) or serial number (18) which is transmitted to a fixed network communication unit (20) to verify the authenticity of the subscriber (10). An enciphering and call sequencing method is provided which can decrease unauthorized detection of these proprietary ID's (18, 19). This method permits efficient roaming by allowing authentication variables for multiple calls to be sent from the "home" system (20) to the "visited" system and stored by the "visited" system for use with subsequent calls. Further, a method is provided which forces the authenticating mobile (10) to use information that only it has available to itself. Furthermore, a method is provided which allows continued encryption integrity during handoffs by maintaining a record of pseudo random events between a subscriber unit (10) and any source radio communication unit (20) (e.g., the number of handoffs that the subscriber (10) has undergone during a given conversation).