While many studies have recently shown how easy and vulnerable protection scheme HDCP (see this article), the all-powerful and famous hacker Bunnie (after the hack original Xbox and the Chumby device) has recently made a very interesting use of primary key HDCP published last year on pastebin.
Bunnie reveals a new use of the primary key HDCP that bypasses some of the possible legal problems. This hack does not decrypts the video; then, without decryption there is no violation, with the result that the DMCA can not take legal action. In summary, also showing that the use of the primary key HDCP is in good faith and does not infringe commercial purposes (ie not around the protections), this hack alters the data, also the possession of the primary key HDCP can be considered a crime.
The main purpose of this hack is to enable the superimposition of video content on a flow HDCP-encrypted. The fact that a simple video overlay become topic of discussion indicates how the DMCA distort rights and freedom. The creation of derivative works or dynamically obtained by superimposing the video (such as picture in picture), before the introduction HDCP appeared to be legal and natural, while the presence of HDCP has made this technically difficult. The idea in the HDCP digital video systems is to cut out a square in the clear within the encoded video, starting from the discs (DVD, BD) to get to the screens (LCT, CRT). Since the overlay video calls or changing the signal light, through intermediate processes, or storing a box in the clear, which can be vulnerable to the copy, the development of these devices has had difficulty in getting the keys for HDCP fear that they may be discovered or used in the construction of HDCP stripper. Moreover, while a manufacturer may develop this feature without requiring authorization, the other would live constantly with the fear that the keys of their devices can be lifted.
Possible uses of the overlay video are numerous, the classic example would be that while you are watching a content X, you might also want to pay attention to content Y. Combine the two together would require a mechanism overlap. Since these mechanisms are banished from the organization that controls the HDCP, consumers are slaves of video producers and distribution networks, because they can remix the video from their point of access to the signal.
The implemetazione specification of this hack allows the stacking of a web browser over the video signals; a concrete example of the potential of this technology is the overlap of Twitter messages, such as "Motor news" program on TV, so that you can see in real time what the community is on the same screen. Some TV programs have tried to include the Twitter messages on the show, this inclusion has always been carried out at source, and users are therefore able to make customizations. Now, thanks to this hack, the same television program (like a political debate), may be perceived differently depending on which keys were inserted into the engine Twitter.
To learn more about this extraordinary work, see the ' article intercommunication in the language original.
