Method of invisibly embedding and hiding data into a text document by modifying selected invisible attributes of invisible characters on a plurality of inter-word intervals, comprising the steps of selecting (10) at least one attribute that is invisible on the space characters used as inter-word intervals,...http://www.google.com/patents/US7240209?utm_source=gb-gplus-sharePatent US7240209 - Methods of invisibly embedding and hiding data into soft-copy text documents
