[mythtv-users] HDCP Key out?

Tortise tortise at paradise.net.nz
Tue Sep 14 20:13:31 UTC 2010


----- Original Message ----- 
From: "Robert McNamara" <robert.mcnamara at gmail.com>
To: "Discussion about MythTV" <mythtv-users at mythtv.org>
Sent: Wednesday, September 15, 2010 3:49 AM
Subject: Re: [mythtv-users] HDCP Key out?

I for one appreciate your responding Robert, thank you.

On Tue, Sep 14, 2010 at 8:33 AM, Brian J. Murrell <brian at interlinx.bc.ca> wrote:
> On Tue, 2010-09-14 at 09:13 -0600, Brian Wood wrote:
>> Thought this might be of interest to folks here:
>>
>> http://entertainment.slashdot.org/story/10/09/14/1211205/HDCP-Master-Key-Revealed
>

>Now, the usual suspects will pop up and say that this sidesteps the
Image Constraint Token (ICT).

Not only am I a suspect, as I am responding, I am guilty of the charge of seeking to understand.

>And a more informed someone will mention that the ICT is *only* a part
of the Blu-ray specification, and that *0* discs ship with it enabled,
and that it is not relevant in any way to broadcast media.

I am not so sure that ICT are not a part of some broadcast media, they after all mere digital tokens (protocol flag according to
wikipedia) and there is no reason I can see why they cannot be transmitted in a broadcast stream, just as they are embedded in a BR 
disc stream.

As I see it the key to ICT working is a two way information flow, to allow the confirmation that there is a display device at the 
end of the chain that is HDCP compliant to send HD to (else SD or nil).  It seems DVB-T is a one way stream, so I expect Robert is 
correct here.

What about IPTV(or an Internet two way protocol?), where a IPTV broadcaster uses a BR ICT enabled disc as the source in HDCP 
equipment and there is a two way digital traffic path?  Seems to me that ICT and HDCP was also designed for this?  Doesn't the 
schema involve a digital chain of any number of compatible intermediary devices / interconnects length?



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