[libdvdcss-devel] Translation french non-technical description of libdvdcss

[Crocy .]

Hello,

Since I had some time and I both understand English and 
French, I did an effort to translate the french non-technical 
description of libdvdcss to English. You can find the text at the bottom
 of this mail and, if your spambox allows, in attachment. Please keep in
 mind that neither English nor French is my mothertongue.
I hope you can use it.


Non-technical description of libdvdcss
(v2.1)



Libdvdcss is a functions library a
program can use to explore the content of a DVD.



1/ The DVD "zones"

All the commercial DVD's and DVD
players include "zone information". Due to this information
DVD's and DVD players are only useable in certain countries because
the zone information from the DVD player has to correspond with the
zone information from the DVD.



2/ The CSS

The CSS (Content Scrambling System)
protects the large majority of the commercial DVD's. Software
developers for DVD player buy at the DVD CCA (DVD Copy Control
Association) keys to decrypt the CSS. At the same time they become
the user instructions of the CSS wich are kept secret.Using his key, and while reading the
DVD, the software communicates with the DVD player to get the
decryption information.



/3 Copying the DVD

This encryptions don't protect the DVD
from copying. It's possible making a physical copy working perfectly
the same (often called bit-to-bit) when using the right equipment.And because the medium has to be
decrypted by the software from the DVD player to show the content on
the screen, this decrypted content is available during the lecture
regardless the used encryption.



4/ The weaknesses of CSS

CSS had been the object of academic
studies wich have discovered how this jamming algorithm works, using
retro-analysis. Later, these studies have shown that the used CSS key
are cryptographically very weak wich has lead to more efficient
decryption algorithms and the discovery of the keys. It's possible
the obtain an exhaustive list on your home computer just in a few
minutes.



5/ How libdvdcss works

This means the list of CSS keys is
perfectly known and a sample of these is distributed with libdvdcss.
Libdvdcss has the same behavior as a DVD player software and uses a
key of this sample. If all the keys from the sample fail, libdvdcss
calculates the rest of the keys and tries them.

It is possible that all this fails,
especially when DVD and DVD player are not in the same zone. As last
remedy, libdvdcss overrides the complete encryption and decrypts the
scrambled stream using the cryptographic weakness of CSS.
Regards,
Christopher 		 	   		  
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.videolan.org/pipermail/libdvdcss-devel/attachments/20120421/760c5642/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: libdvdcss_en.odt
Type: application/vnd.oasis.opendocument.text
Size: 13406 bytes
Desc: not available
URL: <http://mailman.videolan.org/pipermail/libdvdcss-devel/attachments/20120421/760c5642/attachment.odt>