Broadcast encryption

[ema2]

Hi,

I'm a completely newbie of vlc/video stream and so on, so please excuse me if I ask for trivial question

I've yet implemented a broadcast encryption scheme (classic be_enc/be_dec C++ programs) and I'd like to encrypt something more interesting than "hello world" strings.
After some googling, I think working with VLC is the best solution (both client/server, mature code...).

Ok, but where should I place the code!? I mean, the "VLC languange" (mux, demux, sout) is bit complex for me
In the following I try to explain my problem, what I'd like is just something like "you should put this here, that there, look that module for an example"... a map, in fact, to orient me within the huge amount of VLC's code.

In principle, I need a place where storing two keys, a session key K and a 'header' H (so called in BE). The first can be any symmetric key (e.g. AES).
Server side, H is computed from K, knowing the set of legitimate users. Client side, from H, by applying BE decryption I get K (of course iff I'm a legitimate user).

I saw MPEG-TS already supports encryption. Can I use its underlying symmetric scheme?
I could put the key H instead of K, then callback my BE decrypt function to compute K from H. Am I right?
Is there any other better solution?

Further, being only a preliminary version, BE is not carefully optimized. So it should be better for my test to have the possibility for a "light" stream, and maybe adjust the "weight" of the stream. I'm sure it's possible, can you point me in the right direction?

Thank you in advance
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ema

[Rémi Denis-Courmont]

The easiest place where to implement encryption and decryption are the access (reads a stream of bytes from an URL) and access output (writes a stream of bytes to an URL). That's how we currently do HTTP/TLS.

But it depends also on the intended usage (protected transmission or protected storage?), and the properties of the cipher. As you mention, MPEG-TS CSA is in the TS muxer and demuxer - this is encryption tied into the MPEG-TS file format. And Secure RTP is done in the RTP access_demux and stream output, as it is completely dependent on the RTP network protocol.

[ema2]

Thanks a lot!
I need sometime to understand the details (i.e. looking VLC sources)... but I will be back shortly.
bye!
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ema