Digital Media Security

The HDCP copy protection technology has been successfully hacked, through the generation and publication of the overall master key:

http://www.eweek.com/c/a/Security/Intel-Investigating-HDCP-Master-Key-Exposure-384053/

What does this really mean? It is in fact a bit complicated. The content on Blu-Ray disks is protected with something called AACS, and optionally with additional technology called BD+. The Blu-Ray player itself decrypts the content, de-compresses it, and re-scales it as needed for the target display device. Then this content is re-encrypted using HDCP and sent through HDMI to the target display. The display device decrypts the HDCP encrypted content for presentation on the monitor.

With this master key, it is possible to build external devices that will appear as legitimate recipients of HDCP encrypted content with an ability to decode that content, and then do whatever is desired with it (such as re-compress it and make it available through download sites). Will someone do this? It's a good bet; where's there's money to be made via piracy, people will take advantage.

How did this happen? After all, isn't encryption based security supposed to be based on an "ultimate level of obscurity", namely, the problem of "can you figure out which # of our 100 billion possibilities I'm using?".

Yes but...in this case the overall system had a flaw, that allows someone to use some heavy math to "back compute" the master key from a sufficiently sized (but still small, somewhere between 30 and 50) set of "device keys", which get generated through use of the master key.

Overall, what does this say about our digital media security systems?

The answer is a hard pill to swallow: our digital media security system can't really be trusted. Nothing about their basis on "hard cryptography" makes them immune from cracking, and nothing about their implementation directly in custom hardware makes them immune.

So what's needed? What is needed is multiple layers of defense, ideally implemented with both hardware and software mechanisms. Arxan Technologies is predicated on the exponentially increasing difficulty of fully cracking a protected system, when that system is protected by multiple layers of relatively independent security mechanisms. Additionally, the overall architecture should be designed with not just the concept of stopping cracking, but also of anticipating and detecting a cracked environment...and them compromising that environment in a new, subtle but pernicious way.

Always seek to detect and create trouble for the cracker and/or for the user of the crack. I recommend an approach of multiple layers of defense, with both crack blocking strategies and crack detection strategies, all coupled to overt and subtle response strategies.

Intel, in response to this crack, has said they will sue anyone using the master key. Legal solutions to piracy historically have had very limited success. Our technology can and should do better in presenting very difficult barriers to those willing to act outside of the law.