[vlc-devel] [RFC] VLC and CSA encryption/decryption

Rafaël Carré funman at videolan.org
Fri Apr 6 16:50:31 CEST 2012


Le 2012-04-06 06:08, Georgi Chorbadzhiyski a écrit :
> I was adding support for constant code word decryption in tsdecrypt [1] and tried
> to test it using VLC [2] to encrypt an audio stream (video was left not encrypted).
> I was very surprised to see that the decryption was not working. When i started
> digging it turns out that CSA encrypted stream with VLC, can not be decoded by
> libdvbcsa.
> I thought it was a problem with key setup in the VLC code (modules/mux/mpeg/csa.c)
> and to confirm my suspicion I patched csa.c to use libdvbcsa. With the attached patch
> the decryption with tsdecrypt started working.

Did you try vlc 2.0 ?

I sent a bunch of changes for both TS mux and demux in mid-february, it
might have broken CSA although it is unlikely, and those changes are
only in VLC 2.1 so it should be easy to test.

> This poses a problem. Currently CSA encrypted streams with VLC can be decoded with
> VLC but not libdvbcsa (i suspect decryption will have the same problem VLC<->VLC - works,
> libdvbcsa<->VLC - don't work). But if VLC is patched to use libdvbcsa (or fixed to
> setup the CSA key like libdvbcsa), older VLC versions will not be able to decrypt
> the streams.
> I don't know what the correct solution is.

Is there another implementation than VLC's CSA and libdvbcsa that we
could test ?

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