US Patent 7721099 Securing access to documents within multi-function devices

A printer that prints encrypted information in a document can be the key authority for that document. A document containing encrypted information and a source reference can be printed by a printer associated with a key module. The key module contains the key for decrypting the information. A scanner scanning the document obtains the source reference and the encrypted information. The scanner can use the source reference to send a key request to the printer and the printer can respond with the appropriate key. A decryption module associated with the scanner can use the key to decrypt the information. The decrypted information can be incorporated into a second document that can be electronically stored or printed.