One of the most vexing problems with digital information is how to verify its authenticity. As John Markoff points out in his article in yesterday's New York Times, it is "possible to alter digital text, video and audio in ways that are virtually undetectable to the unaided human eye and ear." Markoff reports on researchers from the University of Washington who "are releasing the initial component of a public system to provide authentication for an archive of video interviews with the prosecutors and other members of the International Criminal Tribunal for the Rwandan genocide. The group will also release the first portion of the Rwandan archive." According to the University of Washington researchers, this will be the first time that digital documents can be irrefutably authenticated. The technology used is a "publicly available digital fingerprint, known as a cryptographic hash mark, that will make it possible ... to determine that the documents are authentic and have not been tampered with." Although the concept of the digital hash mark goes back to the 1950s, the new application is far easier to use than its predecessors and will "ensure continuity across many generations ... " The possibility of an authentication system that would be persistent across changing digital formats is extremely compelling, and has many implications for consumers of legal information.