It's not hard to track down the computer hosting a Web page; the domain name can be enough. But computer scientists at AT&T and New York University have now devised a way to blur a document's origin, using a 20-year-old encryption protocol invented by cryptographer Adi Shamir. Called Publius after the pen name of the authors of the Federalist Papers, the system works by encrypting a document a number of different ways that can't be decoded individually. Instead, the meaning becomes clear only after several versions are combined. Publius will send coded copies of a sensitive document to a large number of different servers. Each copy looks like nonsense, even to the person who runs the server. To read a Publius-encrypted file, a computer combs the Web for a few encrypted copies and combines them to reconstruct the original. "There's no central place where everything is stored," says co-inventor Avi Rubin of AT&T.
A 2-month test of the service will be conducted beginning 28 July, and the community seems eager to help. "We've got a lot more volunteers than we can use," says Rubin.