note 44532 rejected from function.mcrypt-decrypt by tomsommer

Note Submitter: php@maddcow.us ---- How do you know if the mcrypt_decrypt worked successfully. I am using the Rijndael algorithm to encrypt/decrypt cookies. But even if I pass it the wrong key, it gives me some code. Is there a way to know if it worked successfully or not. Or should I just encode some sort of thing for me to recognize in the first few characters...like: "PHP|User=x|Timeout=x...." or something? Any recommendations? Alex