<?php
/* (27/09/2006)
 Ramon Forns (ramonforns@gmail.com)
*/

function desencripta($buffer){

	$buffer = preg_replace(\"/([2-9]){1}/\",\'\\1\\1\\1\\1\',$buffer);

	if ((strlen($buffer) % 4) == 0) {

		preg_match_all(\"/.{4}/\",$buffer,$cadena_partes);

		$total = \'\';

		foreach($cadena_partes[0] AS $clau => $parte) {

			$n = \'\';

			if (ereg(\"[0-9]{4}\",$parte)) {

				$n = \'\';

				for ($i = 1;$i<$parte{0};$i++) {

					$n .= substr($total,-1,1);

				}

			} else {

				$p = 0;

				for ($i = 0; $i < 4; $i++)  {

					$y = 3 - $i;

					if ($parte{$i} == \'$\')  {

						$p += pow(4,$y)*1;

					} elseif ($parte{$i} == \'*\') {

						$p += pow(4,$y)*0;

					} elseif ($parte{$i} == \'&\') {

						$p += pow(4,$y)*2;

					} elseif ($parte{$i} == \'#\') {

						$p += pow(4,$y)*3;

					}

				}

				$n = chr($p);

			}

			$total .= $n;

		}



		if (substr($total,-32,32) == md5($mensaje)) {

			return substr($total,0,-32);

		} else {

			return false;

		}

	} else {

		return false;

	}

}



function encripta($buffer){

	$valores = array(\'0\',\'1\',\'2\',\'3\');

	$convert = array(\'*\',\'$\',\'&\',\'#\');

	$buffer .= md5($buffer);

	preg_match_all(\"/.{1}/\",$buffer,$caracters);

	$total = \'\';

	foreach($caracters[0] AS $clau=>$caracter) {

		if ($caracter == $caracters[0][$clau-1]){

			if (ereg(\"[0-9]+\",$total{strlen($total)-1})) {

				$num = substr($total,-1,1)+1;

				$total = substr($total,0,-1);

				$total .= $num;

			} else {

				$total .= \'2\';

			}

		} else {

			$num = ord($caracter);

			$total .= str_replace($valores,$convert,str_pad(base_convert($num,10,4),4,0, STR_PAD_LEFT));

		}

	}

	return $total;

}

?>