… the U.S. Patent and Trademark Office (USPTO) published a new patent filed by Xerox in which it outlines a method by which a blockchain (either a public option or a permissioned alternative) could be used to tie types of data (naming images and video as examples) to a certain period in time.

Source: Proof of Xerox? Copier Giant Pursues Blockchain Time-Stamping Strategy | CoinDesk