A scanner constructed to prevent illicit post-scan modification of a data set. The data set is a representation of visual images printed on a document scanned by the scanner. To prevent illicit post-scan modification, the scanner produces a digital signature which is output in combination with the data...http://www.google.com/patents/US5926550?utm_source=gb-gplus-sharePatent US5926550 - Peripheral device preventing post-scan modification
