[mythtv-users] cablecard

Robert Johnston anaerin at gmail.com
Thu Apr 7 16:56:05 UTC 2005


On Apr 7, 2005 10:24 AM, Joseph A. Caputo <jcaputo1 at comcast.net> wrote:
> I'd be willing to be that such a reverse engineering attempt would fall
> afoul of the DMCA.  

Perhaps.

> Reverse-engineering a driver for the purpose of simply using hardware 
> for which no driver exists on the platform is legal.  

As I thought.

> However, when the *reason* no driver exists is because it would
> compromise the security of the data handled by the card, then the goal
> (or at least a side-effect of the goal) becomes one of circumventing
> encryption, which is explicitly against the DMCA, even if the purpose
> is to exercise you fair use rights.  

>From what I understand, we would not be circumventing any security.
The CableCard has the logic, or a person's broadcaster-issued
decryption key(s), within it to decrypt the encrypted signals. We
would be utilising the encryption, and not breaking or working around
it. Now, if we were coming up with a system to decrypt the
transmissions WITHOUT a CableCard then it would fall afoul of the
DMCA.

To be absolutely candid, if the security is so simple that it can be
decrypted without a card and there is serious danger of that being
discovered, there's no point creating the system in the first place.

The format appears to be similar to a PCMCIA card. If that is so, they
should place the encryption and decryption routines within the card
itself, and have some simple device functions to call (videoArray
DecodeStream(bitArray stream), say), and as the Cable stream is
two-way, updates to the card's parameters (Key validity etc) can be
passed in and validated as completed.

This is all supposition on my part, but I think you could develop for
CableCard without falling afoul of the DMCA. Provided, at least, that
the system is sound.

> The DMCA is not compatible with fair use.

Hear hear!


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