[mythtv-users] Odds of Linux CableCARD support?

Joe Votour joevph at yahoo.com
Fri Apr 7 03:48:38 UTC 2006



--- Joel Ostheller <j.ostheller at gmail.com> wrote:

> Has anyone looked into the legal aspects of
> CableLabs products?
> 
> A while ago I looked at the Cablelabs Cablecard spec
> and it is a semi simple
> interface to design to. It wouldn't be too much work
> for me to design some
> custom hardware that did the proper handshaking to
> setup a channel with the
> cable companies that are using cablecards.
> 
> My only problem with doing this is I have a feeling
> that it might be
> illegal. There is no way I could get my custom
> hardware approved by
> Cablelabs, and in the handshaking process I believe
> I would have to "lie" to
> the cable companies as to what the hardware is (at
> least since it isn't an
> approved cablelabs product). In addition to that,
> say I set up a link and
> have the decryption algorithm, then I believe I
> would need software to do
> the decoding which is probably over my head
> (Hardware engineering is so
> easy, you software engineers are so cool (I'm not
> worthy!)). And then to top
> it all off, there is no way I could ever sell
> anything like this because I'm
> sure Cablelabs or the cable companies would probably
> sue me.
> 
> Anyways... I guess what I am saying is I know
> everyone wants a cablelabs
> cablecard reader for their PC... It would be nice if
> I could provide that
> without getting in trouble.
> 
> On 4/6/06, H P Ladds <householdwords at gmail.com>
> wrote:
> >
> > Mike:
> >
> > http://www.vwbinc.com/products.html (Scroll to the
> very bottom). Perhaps
> > the "Select" nomenclature is important -- I'm not
> certain what it means.
> > Also, on closer inspection, it appears that the
> 5000 model is not available
> > at CompUSA -- only the 4000.
> >
> >
> >
> > _______________________________________________
> mythtv-users mailing list
> mythtv-users at mythtv.org
>
http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
> 

I haven't looked at the legal aspects of CableCard
(because neither I, nor the company that I work for
have interest in it yet), but I have gone through the
legal documentation for DOCSIS (another CableLabs
specification), as I have been previously employed by
companies doing DOCSIS work.

At least in the DOCSIS days, you didn't have to be
DOCSIS certified in order to market a cable modem -
you could claim "DOCSIS compliance", and at that
point, it was buyer beware.  The cable operators
though wouldn't purchase the product, and at first,
they wouldn't even authorize it for use.  Nowadays
though, they'll authorize almost any cable modem
because it's easier for customer service.  If you try
to do something non-DOCSIS compliant, you'll get
kicked off the headend.

With CableCard, I'm not sure if it's the same way, in
fact, I highly doubt that it is, given that everything
is digitally signed.  (In DOCSIS, there was a
CableLabs signature, and a vendor signature, and you
didn't need the DOCSIS signature for operation).

I'd say that if you have to break encryption, you're
likely violating the DMCA.  There are also most likely
patents related to CableCard which could get you into
trouble also.

You also face a technical issue which is (IIRC) that
CableCard provides for revocation of cards.  So, if
you are successful enough in breaking it, if your card
is easily identifiable, it will get added to
revocation lists, and will be rendered useless - in
theory.  There were numerous Motorola cable modems
which were compromised about a couple of years ago
(the Surfboard 3xxx series), and as far as I know
their keys weren't revoked - probably because Motorola
is a key player in CableLabs.

That said, if there was some way that I could assist
in this without violating several laws and liability,
I'd be interested in doing Linux support for a
CableLabs supported CableCard product.

-- Joe

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