Cryptographic method and apparatus with electronically redefinable algorithm

US4914697A · kind A · utility

Assignee

• Motorola, Inc. · US

Inventors

• Ezzat A. Dabbish · Cary, US
• John P. Byrns · Schaumburg, US
• Michael J. McClaughry · Cary, US
• Larry C. Puhl · Huntley, US
• Daniel P. Brown · Elmhurst, US
• Eric F. Ziolko · Schaumburg, US
• Michael W. Bright · Arlington Heights, US

Key dates

• Filing date: Feb 1, 1988
• Grant date: Apr 3, 1990
• Expiry date: Feb 1, 2008

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04L2209/26
• WIPO field: Telecommunications
• WIPO sector: Electrical engineering

Abstract

A cryptographic apparatus for encrypting and decrypting digital words includes a mechanism that permits a cipher algorithm to be electronically stored after the manufacture of the apparatus. The storing mechanism includes at least one electrically erasable, programmable gate array containing a portion of the cipher algorithm and at least one random access memory device coupled to the array for storing digital data generated by the algorithm. A mechanism which is coupled to the gate array and memory device controls the execution of the algorithm for each digital word thereby decrypting encrypted digital words and encrypting non-encrypted digital words.