Microprocessor intended particularly for executing the calculation algorithms of a public code encoding system

US4807288A · kind A · utility

Assignees

• CII Honeywell Bull (Societe Anonyme) · FR
• Etat Francais Represente Par le Ministere des Postes · FR
• Establissement Public de Diffusion dit "Telediffusion de France" · FR

Inventors

• Michel Ugon · Maurepas, FR
• Louis Guillou · Bruz, FR

Key dates

• Filing date: Nov 30, 1983
• Grant date: Feb 21, 1989
• Expiry date: Nov 30, 2003

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04L2209/12
• WIPO field: IT methods for management
• WIPO sector: Electrical engineering

Abstract

One chip microprocessor, which is more particularly designed to execute culation algorithms of a public code encoding system formed by a public function and a secret inverse function of the type comprising at least one programmable read-only memory, a processing unit and an input/output device, wherein it comprises a memory, in which is recorded at least one algorithm corresponding to the performance of said secret function, and wherein the programmable read-only memory contains the secret parameters constituting the secret code and recorded in an area of the read-only memory which is inaccesible from the outside, the processing unit including the multiplying circuits necessary for the execution of the algorithm.