The DRM game

Heileman G. and Jamkhedkar P. are regular contributors for ACM DRM workshop. For many years, they have presented a paper at each workshop. An their papers are worthwhile.

Last year, they presented an interesting It analyzed the different possible strategies for Vendor and Consumer using the game theory. The model was rather simplistic. Thus, there was no big surprise in the outcomes especially when analyzing the baseline game (section 2). Would DRM be unbreakable, Vendor should always sell protected content. For Vendor, it is important decrease the utility of downloaded content versus sold content. Only common sense.

The paper becomes more interesting with section 3 when it analyzes the sub-games. What does the consumer do with content and how Vendor reacts. One outcome is that the higher the penalty, the less Consumers Vendor has to sue. The interesting part is the description of a distribution mechanism with a trust valuation that defines the cost of the content and the associated bonuses. This is a trend that was initiated for many years by Philips labs based on the use of forensic watermark.

I have always problem with that philosophy because it relies on the rather strong assumption that the trust evaluation will work. I have many doubts about that, especially with B2C traitor tracing. Today, you have only limited number of sources on P2P networks, and they do not collude. Let’s now suppose that Consumers understand that they may cheat if either they collude or they issue more instances of sources just to dilute the system… I do not even speak about attacking the reputation system (look in electronic auctions).

Nevertheless, game theory seems an interesting tool to explore strategies. We may expect to see papers in the future with more complex models. I would like to see one which would differentiate authors from vendors/distributors and vendors from authorities.

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