Canon has demonstrated "Uniflow 5," document management system that can prevent users from printing or copying documents containing specific words thanks to a clever keyboard-based security system. "Uniflow (or 'uniFLOW') available on high-end Canon products, in its current form, keeps a record of everything scanned, copied, printed or faxed -- but now, even the content of your document will be parsed before you can interact with a Canon device."
Latest Uniflow has a clever keyword-based security system, which when configured -- will prevent from "print, scan, copy or fax a document" containing "prohibited keyword," such as a client name or project codename. The "start" button simply won't work. The server will email admin a PDF copy of document in question. The system can optionally inform user by email that their attempt has been blocked, but without identifying keyword in question, maintaining security of the system.
If you try to print from your computer, you receive an email that says "sorry, you can't print that." Canon representatives admitted that a determined user could bypass banned keywords by substituting numbers for letters -- b0mb or pr0n -- and indeed, if someone wants to copy a document, they'll find a way to do so.