Editor: A PHP class that can generate a code valid for a limited time.Based on a secret key you can generate a code that is valid only for a limited period of time or as a one time password (OTP), so this class extends the OTP to support the valability of the code in time.The password generated can be verified on another server (or the same) without sending The Secret key and it will be valid only for a limited time.The encription is using is the HMAC Algorithm.It can be usefull to grant access for a limited time to a resource without saving the passwords and it's valability and check of it's valability.