While many researchers recently demonstrated how easy and vulnerable HDCP protection scheme is (recently see here: http://www.dailytech.com/article.aspx?newsid=23373)
The almighty and famous hacker named Bunnie (behind original Xbox hack and Chumby device) recently made a very interesting use of the HDCP master key published last year on pastebin.
Bunnie discloses a new use for the HDCP master key that side-steps some of the potential legal issues. This hack never decrypts video; without decryption, there is no circumvention, and as a result the DMCA cannot apply to this hack. Significantly, by demonstrating a bona-fide commercially significant purpose for the HDCP master key that does not circumvent an access control measure, this hack impairs the equating of trafficking or possession of the HDCP master key to circumvention and/or circumvention-related crimes.
The main purpose of this hack is to enable the overlay of video content onto an HDCP encrypted stream. The simple fact that a trivial video overlay becomes an interesting topic is illustrative of the distortion of traditional rights and freedoms brought about by the DMCA. While the creation of derivative works of video through dynamic compositing and overlay (such as picture in picture) seems intuitively legal and natural in a pre-HDCP world, the introduction of HDCP made it difficult to build such in-line equipment. The putative purpose role of HDCP in the digital video ecosystem is to patch the plaintext-hole in the transmission of otherwise encrypted video from shiny disks (DVDs, BDs) to the glass (LCD, CRT). Since the implementation of video overlay would typically require manipulation of plaintext by intermediate processing elements, or at least the buffering of a plaintext frame where it can be vulnerable to readout, the creation of such devices has generally been very difficult to get past the body that controls the granting of HDCP keys, for fear that they can be hacked and/or repurposed to build an HDCP stripper. Also, while a manufacturer could implement such a feature without the controlling body’s blessing, they would have to live in constant fear that their device keys would be revoked.
While the applications of video overlay are numerous, the basic scenario is that while you may be enjoying content X, you would also like to be aware of content Y. To combine the two together would require a video overlay mechanism. Since video overlay mechanisms are effectively banned by the HDCP controlling organization, consumers are slaves to the video producers and distribution networks, because consumers have not been empowered to remix video at the consumption point.
The specific implementation of this hack enables the overlay of a WebKit browser over any video feed; a concrete example of the capability enabled by this technology is the overlay of twitter feeds as “news crawlers” across a TV program, so that one may watch community commentary in real-time on the same screen. While some TV programs have attempted to incorporate twitter feeds into the show, the incorporation has always been on the source side, and as such users are unable to pick their hashtags. Now, with this hack, the same broadcast program (say, a political debate) can have a very different viewing experience based on which hashtag is keyed into the viewer’s twitter crawler.
You can read more about his excellent work here: http://events.ccc.de/congress/2011/Fahrplan/events/4686.en.html
Our Team will also join the 28c3 lately this year, so feel free to contact us if you have anything special you would like to discuss directly with us in Berlin.