Ah, poor HDCP. Known in expanded form as High-bandwidth Digital Content Protection, it was designed to lock down one of the few remaining unsecured links in the media consumption chain — the connection between computer and display. Unsurprisingly, it didn’t really work out and Apple, unsatisfied with the status quo, has decided to file a patent on a similar system.
Filed in August last year and published last month, the patent, entitled “Securing a HDCP link from graphic processor GPU to video display” describes a method of copy protection that would work in concert with High-bandwidth Digital Content Protection (HDCP), rather than replace it. HDCP has never really posed much of a barrier to the average user, let alone pirates. Even the patent mentions the deficiencies of the protocol:
Unfortunately, the driving of an external display from a computer system may be associated with a number of security vulnerabilities. In particular, video data used to drive the external display may be subject to eavesdropping as the video data is sent over a video interface to the external display. To protect the video data from eavesdropping, a protection mechanism such as High-bandwidth Digital Content Protection (HDCP) may be used to encrypt the video data before the video data is transmitted to the external display. However, an eavesdropper may bypass the protection mechanism by exploiting vulnerabilities in untrusted software on the computer system and/or lapses in the encryption of the video data.
The way Apple wants to combat HDCP’s weaknesses is by decrypting the media to “protected” memory and using that to render the video/audio. The “graphical output” as the patent describes it, would have to support the copy protection, otherwise it would cut the connection between the protected memory and the display, after a indeterminate grace period. The image to the right, taken from the patent, illustrates the system in abstract form.
The thing is, I don’t see how this will make copy-protected video content any more secure. Any type of DRM is only as strong as the weakest link and in this case, this is the actual data stored on the medium. If you can figure out how to rip the video and audio directly from the source (or intercept it, in the case of internet streaming), it doesn’t matter if the link between the GPU and display is impenetrable, you can just use the unprotected raw content instead. It happened to DVD, Blu-ray and HDCP, so I don’t see how Apple thinks it can do better.