CAT(Cellular Authentication Token) is a Strong 2 Factor Authentication (TFA) system that uses a cellular phone to generate a one-time-password. CAT was developed using mature standards based cryptographic technology. CAT generates a new one-time-password (OTP) on the cellular device every 60 seconds. CAT replaces the insecure fixed password with Strong TFA. CAT challenges the hardware proprietary token by its simplicity, availabily and usability;