From nobody@replay.com Mon, 25 Oct 1999 07:01:58 +0200 (CEST)
Date: Mon, 25 Oct 1999 07:01:58 +0200 (CEST)
From: Anonymous nobody@replay.com
Subject: [Livid-dev] css
begin 664 css.tar.gz
[Compressed file removed)
end
From adamp+@andrew.cmu.edu 25 Oct 1999 03:52:26 -0400
Date: 25 Oct 1999 03:52:26 -0400
From: Adam Pennington adamp+@andrew.cmu.edu
Subject: [Livid-dev] css
If this is what I think this is, cool! Everything is now out in the
open to build a DVD player... At least one without menus... If I can
find the time, I will attempt the Linux port.
adam
From dave@pakled.clubnet.org Mon, 25 Oct 1999 01:08:28 -0700 (PWT)
Date: Mon, 25 Oct 1999 01:08:28 -0700 (PWT)
From: Dave dave@pakled.clubnet.org
Subject: [Livid-dev] css
I hate to be a party-pooper, but any dimwit can tell this came from NT, on
VC++.. does the open source community have the right to use this code?
And more importantly, even if we did, to bring up -another- old issue, is
creating an open-sourced CSS cracking algorithm a wise idea?
Those pesky moral issues aside, I must say, this is damn cool. :)
Dave Houston
"There's a spoon in this chili!"
On 25 Oct 1999, Adam Pennington wrote:
> If this is what I think this is, cool! Everything is now out in the
> open to build a DVD player... At least one without menus... If I can
> find the time, I will attempt the Linux port.
>
>
> adam
>
>
>
> _______________________________________________
> Livid-dev maillist - Livid-dev@livid.on.openprojects.net
> http://livid.on.openprojects.net/mailman/listinfo/livid-dev
>
From derek@spider.com Mon, 25 Oct 1999 14:35:54 +0100
Date: Mon, 25 Oct 1999 14:35:54 +0100
From: Derek Fawcus derek@spider.com
Subject: [Livid-dev] css
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On Mon, Oct 25, 1999 at 01:08:28AM -0700, Dave wrote:
>=20
> I hate to be a party-pooper, but any dimwit can tell this came from NT, on
> VC++.. does the open source community have the right to use this code?
Actually this looks a lot like the source to DeCSS. Have a look at
CSSauth.cpp and compare it to my css-auth package. You'll see it's
basically my code, as such this whole source package has to be considered
as being under the GPL. The code in css/CSSscramble.cpp is the stream
decrypting code.
I guessed my slow speed wrt to releasing the source for the decrypt code
would result in someone else posting the code. So enjoy it. This is an
old version and won't decrypt certain W.B. titles. However there is a
valid key key and offset included in that code (the offset is hidden in
css/CSSkeysNt.cpp:CSSgetdiskkey() and has the value of 0x235 and as such
can be used to brute force the other valid keys from a disk.
If you examine the two algorithms (auth and decryt) you'll see that they
are both basically the same:
LFSR1 -> [switchable invert] --\
\
+ (Adder) -> Pseudo random bit stream
/
LFSR2 -> [switchable invert] --/
The two LFSR's are (I belive) the same for both algorithms, but have
a different initialiser.
This bit stream is then used in different ways in the two sets of code.
There are 4 routines which use the above core algorithm, and each one
uses a different setting for the switchable inverts.
The hashing stages at the end of the two title key decryption stages
are very similar (maybe identical) to the rounds in the authentication
routine. i.e. there are two stages to the key decryption here each using
two rounds, whereas the authentication code uses 6 rounds.
At the moment I'm working at combining the two code blocks and eliminating
some look ups. I've already removed one table lookup in the stream decryt
code - another may follow.
One other thing to note - the code posted is valid on little endian
machines only.
DF
--=20
Derek Fawcus derek@spide=
r.com
Spider Software Ltd. +44 (0) 131 475=
7034
PGP/GnuPG Keys available
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