- var_dump: documentation ( source)
- base64_decode: documentation ( source)
- htmlspecialchars_decode: documentation ( source)
<?php
$signature = 'g2siuSxWBKiASwb7Ir%2BRZJ%2FXKV44Scfr3WE8mVK65iCmaj1CF57kfyjueCvqPESu4szZEKDR9ediU5mIAkl2Sa82q6SyXILECMrslJceKk6OLNJm5ftArIYx%2F86iJZlTUN0qefc98pFJSN1QBUZStpfEHU7X1Vr0RqGQslAIrLuDEx8aZ5F0kMVEEN14iP7MlISw9GMAP%2FsE29gtol97kMsdZ9rqTWa5s2YEXg09KdaaoUUaONK5zN7hDp0ATtbn2YX8XvVrVy5Er6c4MvL4oWPyjXIyD9CrQOBduBTMWK32OT1%2BU0sVo2yM5w71pwRu%2BnIu%2Ba2sd6H6uLxI%2FfF7Gw%3D%3D';
$signature = base64_decode(htmlspecialchars_decode($signature));
var_dump($signature);