Method and apparatus for authenication and protection of subscribers in telecommunication systems
Radio frequency based cellular telecommuication 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 and apparatus are provided which can decrease unauthorized detection of these proprietary ID's (18, 19). This method and apparatus permit efficient roaming by allowing authentication variables for multiple calls to be sent from the "home" system (20) to the "visted" system and stored by the "visted" system for use with subsequent calls. Further, a method and apparatus are provided which force the authenticating mobile (10) to use information that only it has available to itself. Furthermore, a method and apparatus are provided which allow continued encryption integrity during handoffs by maintaining a record of pseudo random events between a subscriber unit (10) and any radio communication unit (20) and using that record as an encryption variable.
Motorola, Inc.
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Mary B. Larry C. Louis D.
Flanders Puhl Finkelstein