CableCARD (or how I learned to stop worry and love DRM!)

Posted by nuxi on 2009-Jun-17 at 01:51:20 in SNAFU (Login to reply)

My last post prompted some discussion of what CableCARD is and why it is not an acceptable solution on IRC amongst my friends. CableCARD's version of open access is about as open as the bottom of a locked filing cabinet in a disused lavatory in a basement without any lights and that has a sign on the door saying 'Beware of Leopard'.

The origins of CableCARD come from a 1998 FCC regulation requiring that the decryption module of a cable tv tuner be physically seperate from the rest of the tuner. CableCARD was a device and interface specification designed by CableLabs to comply with this regulation. Ideally this would mean that anyone could create a tuner that accepts CableCARDs, but this isn't quite the case. The CableCARD and the tuner do a key exchange to verify each other. For this key exchange to succeed, both devices need keys signed by CableLabs. Why? So that the CableCARD can re-encrypt the signal before sending it back to the tuner. Also, a tuner's key is only signed if it complies with the copy protection requirements of CableLabs.

The full failure of the FCC to enforce their 1998 rule can only be understood if the original purpose of the ruling is covered. The FCC ruling is the result of a provision in the 1996 Telecommunications Act requiring the FCC to adopt regulations allowing third party devices access to the cable tv system. The explanation for including this open access provision in the TCA is the 1968 Carterfone decision that forced Ma Bell to allow third party devices access to the telephone system. Of course there is a bit of a difference from what resulted from Carterfone and what has become of CableCARD. CableCARD is like telling Ma Bell she can't prohibit devices, but she is allowed to come up with whatever limits she wants. This includes making rules about what the phone is allowed to do with the signal long after it has left the phone system.

The supposed goal of CableCARD was to promote the same innovation that is possible in the telephone system through a physical card with a well defined interface. After the encrypted cable signal was processed by that card, the sky should have been the limit for innovation. Yet the requirements of CableCARD hinder innovation. The CableCARD compliant series 3 TiVo has more restrictions on what you can do with recordings than the series 2. It does not take a genius to figure out that they are missing because of CableCARD's limitations.

The gold standard for determining if a given regulation promotes innovation or should be what I call the two guys in a garage test, a reference to the origins of the Apple I computer. If two guys in a garage can't do it without outside help, then the regulation is not promoting innovation. Without the help of CableLabs to sign the host key, two guys in a garage can't make a CableCARD host device. Thus CableCARD fails the two guys in a garage test.

The idea that two guys in a garage can build a digital cable tuner is not ridiculous or far fetched. A software defined radio tuner built on top of a USRP and controlled by GNU Radio is well within the technical abilities of many engineers. An ATSC tuner was already developed using them in order to prove that the broadcast flag would never be fully enforceable.

Whether or not CableCARD complies with the letter of the 1996 Telecommunications Act or the resulting 1998 FCC regulations is open to debate, but I think it goes without saying that it completely violates the spirit of them. Remember, beware of leopards.