The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 09, 2002
Filed:
Dec. 01, 1998
Anoop Bhattacharjya, Sunnyvale, CA (US);
Hakan Ancin, Cupertino, CA (US);
Seiko Epson Corporation, Tokyo, JP;
Abstract
A scanner ( ) derives a digital image of a document that it scans optically, an image-processing circuitry ( ) extracts a representation of a non-planner graph. A small-processor “smart card” derives from the first graph a second graph that is isomorphic to it and related to it in accordance with a secret permutation matrix. The image processor then embeds a representation of that graph into the image and sends the results to a printer ( ) to generate a copy. A second scanner ( ) generates a digital image of the copy, and processing circuitry ( ) extracts the two isomorphic graphs, which it conveys to a verifier circuit ( ) as well as the smart card ( ). By repeatedly generating and submitting to the verifier ( ) test graphs that are isomorphic to the extracted graphs, the smart card ( ) can demonstrate, without revealing the secret permutation matrix, that it is in possession of that permutation matrix. It does so by sending the verifier a permutation matrix that relates the test graph to the extracted graph of the verifier's choice.