[linux-dvb] Re: Undocumented (?) ioctl

[a.most@softhome.net]

> Hello,
> 
> Can anyone tell me what the CA_SET_DESCR ioctl call does ? None of the CA
> ioctls are documented, and this one is not obvious.

Good Question! It has been put here on the list a few times. But I fear,
nobody will really answer here because of (supposed to be) legal issues.

What I found so far: this ioctl is supposed to set the descrambler keys for
the Conditional Access. 16 pairs of keys (64 bit, even and odd, defined by
"parity") can be set on the AV7110 (Why does the driver allow only 12 ?). 
These keys would usually be extracted from the TS stream and decoded
by the CI with CAM and a valid card. They are automatically written into 
the key register(s), so you don't have to bother. 
Using this ioctl directly doesn't seem to have an effect.
You probably have to reverse engineer the firmware to really find out...

Regards, Andreas.


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