#!/usr/bin/perl -s
# coded by Oromis92
# <nicolabbi@libero.it>




$key = shift or die "usage: perl $0 [-d] <key> [infile [>> outfile]]\n";
while (<>) {
	$plain .= $_;
}
chomp($plain);
@key = split //,$key;
@plain = split //,$plain;
@key = map(ord, @key);

@S = 0..255;
foreach $i (0..255)  { 
	$K[$i]=$key[$i%($#key+1)]; 
}



sub KSA {
	$j=0;
	for ($i=0;$i<255;$i++){
		$j = ($j + $S[$i] + $K[$i])%256;
		$temp = $S[$i];
		$S[$i] = $S[$j];
		$S[$j] = $temp;
	}
}



sub PRGA {
	$i = 0;
	$j = 0;
	for ($count=0;$count<length($plain);$count++) {
		$i = ($i + 1)%256;
		$j = ($j + $S[$i])%256;
		$temp = $S[$i];
		$S[$i] = $S[$j];
		$S[$j] = $temp;
		$t = ($S[$i] + $S[$j])%256;

		if (!$d) {
			$output = sprintf('%X', ($S[$t] ^ ord($plain[$count])));
			if (length($output) % 2 == 0) {
				$result .= $output;
			} else {
				$output .= "0" ;
				$result .= $output;
				$output = "";	
			}
		} else {
			if ($count*2 < length($plain)) {
				$output = chr($S[$t] ^ (hex(substr($plain,($count*2),2))));
				$result .= $output;
				$output = "";
			}
		}
	}
	print "$result\n";
}
KSA;
PRGA;