Ex parte HYATT et al. - Page 11

          Appeal No. 95-0143                                                          
          Application 07/865,849                                                      

          decrypts Q using the secret key, S, to get P and encrypts R using           
          P to get X.  The key then sends X back to the lock.  The lock               
          encrypts R using P to get X and compares the two.  If there is a            
          match, the lock allows entry.                                               
               Using this process, Pogue meets the above mentioned                    
          objectives, the private key as well as the secret key are never             
          transmitted.  This provides a high level of security even if all            
          communication can be monitored and all aspects of the design are            
          known.  In addition, only the key’s ID and the secret key are               
          stored in the key.  This provides a simple design for the key               
          that can operate at very low power.                                         
               On the other hand, Clark does not meet these objectives.               
          Clark stores lock ID codes and their corresponding access codes             
          in the key which requires a much larger amount of memory storage            
          in the key.  In addition, Clark does not provide a high level of            
          security as taught by Pogue because Clark transmits the access              
          code which can be intercepted by someone monitoring the                     
          transmission, thereby allowing unauthorized persons to defeat the           
          security of the lock.                                                       
               Those skilled in the art having both the teachings of Pogue            
          and Clark before them would have been led away from using the               
          Clark security system which does not provide a high degree of               


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