Here's an odd twist that might give new life to the dying horse of music digital-right management. Microsoft has just been awarded a U.S. patent for a distributed DRM system -- it works over peer-to-peer networks -- which uses encrypted public and private keys as the licensing mechanism. This is significant because, while centralized music stores like Apple's iTunes have forsaken DRM, the Microsoft patent would enable peer-to-peer networks to reemerge as viable, albeit protected, content sources.The patent, number 7,594,275, is entitled simply, "Digital rights management system." Granted today (Sept. 22), it was filed in October, 2003, which undercuts the implication in my introduction, about why anyone would bother at this late date.

In 2003, when Microsoft's patent application was filed, the whole "Web wants to be free" versus "evil corporations with their DRM" argument was in full flower. That debate hasn't been resolved -- if you ask me, there's still no justification for people stealing songs.

However, it has been rendered moot, in a paradoxical manner. On the one hand, the RIAA's aggressive legal pursuit of song-downloading grandmas squandered the precious little sympathy the record companies might have had. But at the same time, the marketplace essentially moved beyond DRM. Consumers became more sophisticated, and most slowly became inured to the idea they should pay for their music. The turning point came when Apple's iTunes and Amazon pulled back from DRM.

So sure, there's still music theft, and not just in China (there, it's called the market). But DRM is now more properly spoken of in reference to movies and DVDs, where copyright protection will remain in place until Hollywood's last gasp.

In this context, one would think that Microsoft's new patent might be irrelevant. However, it's not, because of its interesting peer-to-peer angle. Indeed, one can foresee a time when peer-to-peer networks reemerge from their current sub-rosa position and become popular, brand, public-facing methods of distributing content. When they do, Microsoft may be positioned to reap some serious royalties.

Here's how Microsoft describes the peer-to-peer distributed angle, in the "background" section of the patent:

"In a conventional DRM system, license acquisition requests are processed by a centralized license server. This makes the centralized license server heavy-loaded, complex, and expensive to run and maintain, and makes it a weak link in the DRM system. For example, failure of the centralized license server may disrupt normal DRM services. Additionally, small content providers, such as a peer in a peer-to-peer network, may not be able to afford the cost of providing and/or utilizing the services of the centralized license server.

Peer-to-peer networks have emerged as a popular way to share large amounts of data, such as by peers downloading songs that are referenced as being available for download through a peer-to-peer website. Most peer-to-peer networks, however, do not have digital rights management or access control. Consequently, peer-to-peer networks can be liable for contributing to the infringement of the copyright in works that are referenced as being available for download by the peer-to-peer networks.

Accordingly, there is a continuing need for a distributed public licensing infrastructure for digital rights management systems."

The Microsoft patent uses partial licenses, consisting of both a public and a private key, to provide customers with the right to decrypt the content they access over the peer-to-peer network. Or, as they put it more formally in the patent: "Partial licenses are combinable to form a formal license that may be utilized to output the content."

Here's a flowchart from the patent, showing how the whole shebang works:

Diagram from Microsoft's peer-to-peer DRM patent. (Click picture to enlarge, and to see four more diagrams/flowcharts.)

In closing, the one big thing which strikes me -- and I should note that I'm not a lawyer; I just play one on my blog -- is that, like many patents, this one doesn't seem to be much of a stretch beyond prior art. (My argument on that score would be the notations about key sharing, key redistribution, and asymmetric encryption contained in the "reference" section of the patent. No matter; this is the same deal as with thousands of other patents. We all know the deal with the backlogged and short on examiners USPTO. Namely, you're gonna get your patent, and then you defend it in court later on if you have to.

The second leg of this observation is that Microsoft's lawyer have their eye on the broad-claims prize, and the possible revenue-producing future of this patent, in its very last paragraph. To wit:

"Although the invention has been described in language specific to structural features and/or methodological acts, it is to be understood that the invention defined in the appended claims is not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as exemplary forms of implementing the claimed invention."

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Alex Wolfe is editor-in-chief of InformationWeek.com.