Encryption and authentication method and circuit for synchronous smart card

US5825882A · kind A · utility

Assignee

• Gemplus Card International · FR

Inventors

• Jacek Kowalski · Saint-Maximin-la-Sainte-Baume, FR
• Michel Martin · Eybens, FR
• Jacques Stern · Paris, FR
• Antoine Joux · Cesson-Sévigné, FR

Key dates

• Filing date: Jul 31, 1995
• Grant date: Oct 20, 1998
• Expiry date: Jul 31, 2015

Classification

• Technology area (CPC G): Physics
• CPC primary: G07F7/0866
• WIPO field: IT methods for management
• WIPO sector: Electrical engineering

Abstract

Encryption circuits and methods, in particular for smart cards, are disclosed. Smart cards without microprocessors may be authenticated very simply by using encryption with a secret card data table on which recursive cycles are executed. During each cycle, a word is read out of the table, said word being at an address that is at least partially defined by the word read out in the previous cycle. The new address preferably consists of several bits from the previous word and a bit from internal card data, external data supplied by a card reader, or a register containing a partial encryption result.