TMCTF2015-crypto500.php

<?php
	$cs=str_split("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ");
	foreach ($cs as $i) {
		test($i);
		foreach ($cs as $j) {
			test($i.$j);
			foreach ($cs as $k) {
				test($i.$j.$k);
			}
		}
	}
	$sol=[];
	foreach (array_merge($cs,["+","/"]) as $i) {
		if(!isset($a[$i])) $sol[]=$i;
	}
	usort($sol, function($a,$b){return ord($a)-ord($b);});
	echo implode("",$sol)."\n";
	echo 'TMCTF{'.sha1(implode("",$sol)).'}';
	function test($s){
		global $a;
		foreach(str_split(base64_encode($s)) as $c) $a[$c]=1;
	}
?>