Edward Felten analyzes Googe's DRM (Digital Rights Management) used for its new video service.

Here is an excerpt:

"Last week Google introduced its video service, which lets users download free or paid-for videos. The service's design is distinctive in many ways, not all of them desirable. One of the distinctive features is a DRM (anti-infringement) mechanism which is applied if the copyright owner asks for it. Today I want to discuss the design of google video's DRM, and especially its privacy implications."

"First, some preliminaries. Google's DRM, like everybody else's, can be defeated without great difficulty. Like all DRM schemes that rely on encrypting files, it is vulnerable to capture of the decrypted file, or to capture of the keying information, either of which will let an adversary rip the video into unprotected form. My guess is that Google's decision to use DRM was driven by the insistence of copyright owners, not by any illusion that the DRM would stop infringement."

"The Google DRM system works by trying to tether every protected file to a Google account, so that the account's username and password has to be entered every time the file is viewed. From the user's point of view, this has its pros and cons. On the one hand, an honest user can view his video on any Windows PC anywhere; all he has to do is move the file and then enter his username and password on the new machine. On the other hand, the system works only when connected to the net, and it carries privacy risks."

"The magnitude of privacy risk depends on the details of the design. If you're going to have a DRM scheme that tethers content to user accounts, there are three basic design strategies available, which differ according to how much information is sent to Google's servers. As we'll see, Google apparently chose the design that sends the most information and so carries the highest privacy risk for users."