Database Nation: Turning your computer against you

Hold an expensive piece of paper up to the light and you are likely to see a watermark, a design that's produced by pressing the paper with a wire design during the drying process. Watermarks were developed in Italy during the thirteenth century. Italian papermakers used them as a way of labeling their wares - and also a way of detecting counterfeits and forgeries.

Similar watermarks are under development for watermarking documents and images downloaded over a computer.

Many of these systems rely on running 'trusted software' on the end user's computer. The end-user software meshes with the software running on the publisher's computer. The software on the publisher's computer assures that each user will be given his or her own unique, personalised, and watermarked version of the document. The software on the client's computer monitors the end user. The client software records the use, attempts to prevent the user from making an unauthorized copy, and, in some cases, reports statistics back to the publisher. The client software is called "trusted" because end users need to trust it: once the software is running on the end user's computer, there is no effective way to audit its use.

Today's computer are rarely willing conspirators to such systems. A general-purpose desktop computer running Windows or the Macintosh operating system can easily be reprogrammed to circumvent any sort of dictate from copyright owners. But computers of the future could certainly be equipped with hardware that enforced particular copyright restrictions.

InterTrust, based in Silicon Valley, is one of several corporations laying the groundwork for such a system. InterTrust has developed a comprehensive scheme for delivering digital content to end users, with predefined "business rules".

The system automatically tracks each user, charges her the appropriate amount of money, prohibits her from removing copyright information, and prevents her from trying to make use of rights that she hasn't purchased.

With InterTrust's system, you might pay five cents to view a document on the Internet, an additional ten cents to print it out and one cent for the right to sell it to a friend - who would then be charged five cents for the right to read more than the first few paragraphs. InterTrust is banking on the idea that large corporations will be willing to distribute large amounts of information at very low prices if they can be assured that they will be paid for all legitimate use - and that illegitimate use will automatically be prohibited.

Digital signatures are one of the basic building blocks of rights management systems such as InterTrust's. A digital signature is a cryptographically sealed block of information that can be created by one person (or organization) and verified by another. Using a digital signature system it's possible to stamp a document with a unique identifier, signer's name, location, the time, and other sorts of information.

Signatures are quite flexible. Like watermarks, a song could be signed once by its author, again by its publisher, and again by each person who wants to transmit it electronically. But digital signatures can also be verified very quickly. Electronic networks such as the Internet can be programmed not to carry information unless the person who is transmitting it also has digitally signed it. Computers, likewise, can be programmed not to accept information unless it is properly signed.

Watermarks and digital signatures are powerful tools for eliminating the anonymity that until now has been inherent in digital media. Citizens of the future may look back at the last days of the twentieth century and marvel that identical copies of books, compact discs, video tapes, and electronic information were ever distributed to thousands, let alone millions, of consumers. They may be even more amazed still that all these consumers possessed computers, tape decks, and copying machines capable of stamping out limitless numbers of perfectly usable, if not identical, copies. What was there to stop widespread piracy, other than people's consciences?

Indeed, the fear of watermarking systems may very well stop much of the unsophisticated, casual piracy so pervasive today. But these systems will probably not make serious inroads against determined insiders, who have access to the digital information before the watermark is laid down.

And even if watermark systems become widespread, determined pirates will still find untraceable ways of purchasing disks they are intent on copying. MCA might mandate that nobody can buy a compact disc without showing a photo ID and being fingerprinted. But what won't stop some criminal copyright gang from breaking into the house of an innocent teenager, stealing all her tunes, spitting out millions of copies, and letting her take the fall.

Ultimately, watermark systems are about institutionalizing fear and control as tools for preventing copyright theft.

** All this week, Silicon.com is publishing exclusive extracts from Simson Garfinkel's latest book Database Nation, which poses a disturbing question: how can we protect our basic rights to privacy, identity and autonomy when technology is making invasion and control easier than ever before? The serialisation continues tomorrow, and on Friday, we've got 25 copies of the book up for grabs. See Silicon.com all week for further details.

Database Nation is available from all good bookshops, for more information see http://www.oreilly.com