Patent ID: 6516415
Filing Date: 2003-02-04
Classification: G06F

Abstract:
A device for maintaining a secret code, which is enclosed in an integrated circuit package and connected to an external power supply located at the outside of the integrated circuit package, comprising:means, located within the integrated circuit package, for producing a first part of the secret code; a non-volatile memory, coupled to the producing means, for holding the first part of the secret code; means, located within the integrated circuit package, for generating a second part of the secret code according to external visa data received from the outside; a volatile memory, coupled to the generating means and powered by the external power supply, for dynamically holding the second part of the secret code; wherein the generating means is remotely connected to an external authority unit and comprises: first means for storing request data ready to be sent to the authority unit; second means for storing the external visa data received from the authority unit; and means, coupled to the first storing means and the second storing means, for computing a first mathematical function of the request data and the external visa data to reproduce the second part of the secret code; and the authority unit comprises: third means for storing the request data received from the generating means of the device; fourth means for storing the second part of the secret code; and means, coupled to the third storing means and the fourth storing means, for computing a second mathematical function of the request data and the second part of the secret code to generate the external visa data, the first mathematical function being the inverse of the second mathematical function.