- rtrim: documentation ( source)
- base64_decode: documentation ( source)
<?php
$cookie = "n4LMHuO1OVbk6ggCOfIxA4+t0SVeuc7hysOaGR7ohp9Z9FSDh5jSQ8A0YEWjqi1vbrDG6QZ7CCQfVRPwK3Nm3J4bt1dOUd0J4pmNspfPDeYe7bSIhmks9w==";
$secret_key = "TDS0ZUis";
$secreto_revelado = rtrim(mcrypt_decrypt(MCRYPT_DES, $secret_key, base64_decode($cookie), MCRYPT_MODE_ECB),"\0");
print $secreto_revelado;