- var_dump: documentation ( source)
- base64_decode: documentation ( source)
- unserialize: documentation ( source)
<?php
$signed_string = '{"Tzo4OiJzdGRDbGFzcyI6MDp7fQ==":"1","adminhash":null,"ajax":null,"postvars":null}';
var_dump($signed_string, base64_decode($signed_string), unserialize(base64_decode($signed_string)));