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. 27, 2004
Filed:
Dec. 22, 1999
R. Drews Dean, Cupertino, CA (US);
Matthew K. Franklin, Palo Alto, CA (US);
Xerox Corporation, Stamford, CT (US);
Abstract
A symmetric key encryption system includes a printer or copier for performing decryption in two passes. During a first pass an encrypted image is decrypted to define a first partially decrypted image and during a second pass a complement of the encrypted image is decrypted to define a second partially decrypted image. The first partially decrypted image is formed when the encrypted image is rendered onto a first recording medium through a stencil. The stencil, which is a random arrangement of holes, is overlaid on the first recording medium to permit only selected portions of the encrypted image to be rendered on the recording medium. During the second pass, the complement of the encrypted image is rendered on a second recording medium through a complement of the stencil to yield the second partially decrypted image. Overlaying and aligning the first partially decrypted image and the second partially decrypted image finally decrypts the encrypted image.