DeCSS en Perl (Era Re: Hola a todos!)

[Ernesto Hernandez-Novich]

On 30 Sep 2001, Miguel E. Rodriguez wrote:
> Alguien de esta lista tiene el script en perl de 6 lineas
> que permite desencriptar DVDs. Estoy interesado en adjuntarlo
> a mi firma.

El más corto es

#!/usr/bin/perl
# 472-byte qrpff, Keith Winstein and Marc Horowitz <sipb-iap-dvd at mit.edu>
# MPEG 2 PS VOB file -> descrambled output on stdout.
# usage: perl -I <k1>:<k2>:<k3>:<k4>:<k5> qrpff
# where k1..k5 are the title key bytes in least to most-significant order

s''$/=\2048;while(<>){G=29;R=142;if((@a=unqT="C*",_)[20]&48){D=89;_=unqb24,qT,@
b=map{ord qB8,unqb8,qT,_^$a[--D]}@INC;s/...$/1$&/;Q=unqV,qb25,_;H=73;O=$b[4]<<9
|256|$b[3];Q=Q>>8^(P=(E=255)&(Q>>12^Q>>4^Q/8^Q))<<17,O=O>>8^(E&(F=(S=O>>14&7^O)
^S*8^S<<6))<<9,_=(map{U=_%16orE^=R^=110&(S=(unqT,"\xb\ntd\xbz\x14d")[_/16%8]);E
^=(72, at z=(64,72,G^=12*(U-2?0:S&17)),H^=_%64?12:0, at z)[_%8]}(16..271))[_]^((D>>=8
)+=P+(~F&E))for at a[128..$#a]}print+qT, at a}';s/[D-HO-U_]/\$$&/g;s/q/pack+/g;eval

El más rápido (el por qué se deja como ejercicio para el lector ;-)

#!/usr/bin/perl -w
# 531-byte qrpff-fast, Keith Winstein and Marc Horowitz <sipb-iap-dvd at mit.edu>
# MPEG 2 PS VOB file on stdin -> descrambled output on stdout
# arguments: title key bytes in least to most-significant order
$_='while(read+STDIN,$_,2048){$a=29;$b=73;$c=142;$t=255;@t=map{$_%16or$t^=$c^=(
$m=(11,10,116,100,11,122,20,100)[$_/16%8])&110;$t^=(72, at z=(64,72,$a^=12*($_%16
-2?0:$m&17)),$b^=$_%64?12:0, at z)[$_%8]}(16..271);if((@a=unx"C*",$_)[20]&48){$h
=5;$_=unxb24,join"", at b=map{xB8,unxb8,chr($_^$a[--$h+84])}@ARGV;s/...$/1$&/;$
d=unxV,xb25,$_;$e=256|(ord$b[4])<<9|ord$b[3];$d=$d>>8^($f=$t&($d>>12^$d>>4^
$d^$d/8))<<17,$e=$e>>8^($t&($g=($q=$e>>14&7^$e)^$q*8^$q<<6))<<9,$_=$t[$_]^
(($h>>=8)+=$f+(~$g&$t))for at a[128..$#a]}print+x"C*", at a}';s/x/pack+/g;eval	

No obstante, yo prefiero

http://www.copyleft.net/item.phtml?page=product_1174_front.phtml
-- 
Ernesto Hernández-Novich - Running Linux 2.4.9 i686 - Unix: Live free or die!
-----BEGIN GEEK CODE BLOCK-----
Version: 3.1
GCS/E d+(++) s+: a C+++$ UBLAVHIOSC*+++++$ P++++$ L+++$ E--- W+ N++ o K+++ w--
O- M- V- PS+ PE Y+ PGP>++ t+ 5- X+ R* tv+ b++ DI+++$ D++ G++ e++>+++ h r% y+
-----END GEEK CODE BLOCK-----

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