- unserialize: documentation ( source)
- base64_encode: documentation ( source)
<?php
$t = '26%7CaU0qPfB4CCAOFIxzW9F5KA%3D%3D%7CAi6ivHQUFe9lwMc1a0tVmGJNHWFd%2BVafbvsRic5iL2LE3Bh72665IZ1vDTwdKEV3%7Cb6M4oPHIy8m4KwnoveOoiQqXbFgoGc3wX261BRuOwsk%3D';
$t = base64_encode($t);
echo unserialize($t);