rduarte (owner)

Revisions

gist: 89542 Download_button fork
public
Description:
algorithm based on base64 for general proposes
Public Clone URL: git://gist.github.com/89542.git
Embed All Files: show embed
codificador.php #
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<?php
function codificar($valor, $chave){
 
	if (($chave = codificacao_chave($chave)) !== false){
		list($inicio, $fim) = $chave;
	} else {
		return false;
	}
	$base = base64_encode($valor);
	$base = str_replace('=', '', $base);
	$base = strrev($base);
	$md5 = md5($valor);
	$base = (substr($md5, 0, $inicio) . $base . substr($md5, -$fim));
 
	return $base;
}
 
function decodificar($valor, $chave){
 
	if (($chave = codificacao_chave($chave)) !== false){
		list($inicio, $fim) = $chave;
	} else {
		return false;
	}
	$hash = (substr($valor, 0, $inicio) . substr($valor, -$fim));
	$base = substr($valor, 0, -$fim);
	$base = substr($base, $inicio);
	$base = strrev($base);
	$cmp = (strlen($base) % 4);
	if ($cmp > 0) $base .= str_repeat('=', $cmp);
	$base = base64_decode($base);
	$md5 = md5($base);
	$md5 = (substr($md5, 0, $inicio) . substr($md5, -$fim));
 
	return (($md5 == $hash) ? $base : false);
}
 
function codificacao_chave($chave){
 
	$valor = md5($chave);
	$t = strlen($valor);
	$dig1 = '';
	$dig2 = '';
 
	for ($i = 0; $i < $t; $i++){
		$ch = substr($valor, $i, 1);
		if (is_numeric($ch) && ($ch !== '0')){
			if ($dig1 == ''){
				$dig1 = $ch;
			} elseif ($dig2 == ''){
				$dig2 = $ch;
			} else {
				break;
			}
		}
	}
 
	return (($dig1 != '') && ($dig2 != '')) ? array($dig1, $dig2) : false;
}
?>