This is illegal

Keith Winstein and Marc Horowitz are programmers at MIT in the US. They are clever guys, and have been able to come up with a DVD anti-encryption program that runs with just seven lines of Perl. The pair decided to write and publish the code to

Keith Winstein and Marc Horowitz are programmers at MIT in the US. They are clever guys, and have been able to come up with a DVD anti-encryption program that runs with just seven lines of Perl. The pair decided to write and publish the code to demonstrate just how flimsy current DVD encryption is, and already the seven lines are being scanned onto T shirts, added to email .sigs, and generally shown around.

Not lone ago DeCCS, a similar, though not as compact piece of code, was the center of a legal battle between the publishers of 2600 Magazine and the Motion Picture Association of America. The court ruled that even linking to the DeCCS code was illegal. This sparked a sudden interest in T shirts depicting the code, and even songs using the code as lyrics. Now 'qrpff', the name of the code, has come along - small enough to distribute on a business card say the creators.

So what is this terribly malicious and copyright threatening string of commands. Well, I'm glad you asked:

#!/usr/bin/perl -w
# 531-byte qrpff-fast, Keith Winstein and Marc Horowitz
# 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;$t^=(72,@z=(64,72,$a^=12*($_%16 -2?0:$m&17)),$b^=$_%64?12:0,@z)[$_%8]}(16..271);if((@a=unx"C*",$_)[20]&48){$h =5;$_=unxb24,join"",@b=map{xB8,unxb8,chr($_^$a[--$h+84])}@ARGV;s/...$/1$&/;$ d=unxV,xb25,$_;$e=256|(ord$b[4])<<9|ord$b[3];$d=$d8^($f=$t&($d12^$d4^ $d^$d/8))<<17,$e=$e8^($t&($g=($q=$e14&7^$e)^$q*8^$q<<6))<<9,$_=$t[$_]^ (($h=8)+=$f+(~$g&$t))for@a[128..$#a]}print+x"C*",@a}';s/x/pack+/g;eval

I feel so evil now.