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From livid@cpsumner.freeserve.co.uk Wed, 10 Nov 1999 14:18:11 +0000
Date: Wed, 10 Nov 1999 14:18:11 +0000
From: Chris Sumner livid@cpsumner.freeserve.co.uk
Subject: [Livid-dev] DVD filesystem with integrated decryption?

Has anyone thought of integrating the CSS algorithms into the filesystem
code used for reading DVDs? This would allow transparent reading of DVDs
and make it easier to write DVD players. Might have to be compiled as a
seperate module though, to avoid possible legal problems. :)
-- 
Chris Sumner

From alan@lxorguk.ukuu.org.uk Wed, 10 Nov 1999 14:23:13 +0000 (GMT)
Date: Wed, 10 Nov 1999 14:23:13 +0000 (GMT)
From: Alan Cox alan@lxorguk.ukuu.org.uk
Subject: [Livid-dev] DVD filesystem with integrated decryption?

> code used for reading DVDs? This would allow transparent reading of DVDs
> and make it easier to write DVD players. Might have to be compiled as a
> seperate module though, to avoid possible legal problems. :)

Right now the kernel simply knows how to pass auth data around for both
the free and nonfree DVD stuff. I'd prefer to keep it that way. 

Alan

From pvolcko@concentric.net Wed, 10 Nov 1999 10:43:11 -0500 (EST)
Date: Wed, 10 Nov 1999 10:43:11 -0500 (EST)
From: pvolcko@concentric.net pvolcko@concentric.net
Subject: [Livid-dev] DVD filesystem with integrated decryption?

Yes, Andreas Bogk brought this up a couple times over the last few months.
Once farily recently.  

The general reaction was against the specific method he was suggesting
(actually getting such a change into the Kernel source tree).  However, I
don't think anyone was really all out against the functionality goal.
Where to implement it seems to be the main question.

I'm of the opinion that it really belongs in user space, and with applications
dealing with DVD-Video discs.  I consider CSS akin to PGP or other user space
encryption tools.  That is, CSS is not part of the UDF spec nor even DVD.  It
only applies to DVD-Video, and even then it is optional.  As such it should
be implemented as a library with a few simple calls:

- Point it at the dvd drive device
- Initialize
- Authenticate
- Set Title
- Decode Data

It should be thread safe.  And the Decode Data function will simply take a 2K
buffer as an arguemnt.  After the call completes the data is decrypted.  If
the input data wasn't encryped to begin with, it is left as is.

A kernel module (third party, not part of the
official kernel) is a possibility as well, but it would have to be fairly
tightly coupled with UDF.  I don't know if it is possible to intercept UDF
read and seek calls, but this is what would be needed to really do this as a
seperate add on module (without UDF implementation).  Otherwise a DVD-Video
specific microUDF implementation with CSS integrated might be the way to go,
preferably without the need to mount the DVD before using it.

Paul Volcko
LSDVD

On Wed, 10 Nov 1999, Chris Sumner wrote:

> Has anyone thought of integrating the CSS algorithms into the filesystem
> code used for reading DVDs? This would allow transparent reading of DVDs
> and make it easier to write DVD players. Might have to be compiled as a
> seperate module though, to avoid possible legal problems. :)
> -- 
> Chris Sumner
> 
> 
> _______________________________________________
> Livid-dev maillist  -  Livid-dev@livid.on.openprojects.net
> http://livid.on.openprojects.net/mailman/listinfo/livid-dev
> 


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