[WEB4LIB] RE: Gray Hats Re: Re: Jack Valenti: Copyright and

[Tony Barry]

At 2:53 PM -0800 20/3/01, Chris Deweese wrote:
>Again we see hacking being classified in a "dark" manner.  As matt 
>said, hacking is about the method and not the context.  Might I 
>suggest this story:
>Seven-Line Perl code beats DVD Crypto
>http://www.theregister.co.uk/content/4/17444.html
>A seven-line program written in perl script beats the MPAA's DVD 
>encryption scheme.  The program was written by a former MIT student 
>and a currnet undergrad.  A pure example of hacking being about the 
>method.
>These guys didnt write this program to copy dvd's.  They wrote it to 
>prove how weak the system currently used is.  deCSS the original 
>program to decrypt dvds was written by a 15 year old kid.
>I see no wrong doing in this.  But the MPAA has been in an uproar 
>about it.  Why? Because it shows how little money they really 
>invested in coming up with a copy protection system.  More money is 
>probably invested in child safety caps for medicine.(thats a guess 
>not a fact)

The code is -

#!/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

It has also been written as an ever shorter c++ program and(using a 
bit of a trick) as a prime number.

Also the web4lib archives may be in breach of the copyright 
legislation for publishing this ;^)

Tony
-- 
phone  +61 2 6241 7659
mailto:me at Tony-Barry.emu.id.au
http://purl.oclc.org/NET/Tony.Barry