Document copy authentication

US5157726A · kind A · utility

Assignee

• Xerox Corporation · US

Inventors

• Ralph C. Merkle · Santa Clara, US
• Dan S. Bloomberg · Palo Alto, US
• John Seely Brown · Palo Alto, US

Key dates

• Filing date: Dec 19, 1991
• Grant date: Oct 20, 1992
• Expiry date: Dec 19, 2011

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04L9/3247
• WIPO field: Control
• WIPO sector: Instruments

Abstract

A system for authenticating a hard copy of an original document. The system employs a special copying machine at the sender's end together with a special ID card (smart card) or other user identification for activating the special machine, and a special copying machine at the receiving end. At the sender's station, the original document and ID card are inserted into the machine. The latter digitizes the document text, to produce a digital signature which incorporates unique information from the sender's ID card. This machine then produces a hard copy of the document to which is added the digital signature. The sender retains the original, but forwards the copy to the recipient or receiver. The receiver then inserts the received copy into the machine at his location, which digitizes and processes the document text and signature and indicates whether the digital signature is valid. Preferably a dual key authentication system is used, with the digital signature incorporating the sender's secret signing key, and the receiver using the related public key in the validation process.