The methods and systems of the present invention addresses the problem of identity theft associated with the use of a credit/debit card. A security code having a predetermined expiration, or equivalently lifetime, is generated. The cardholder is informed that his/her current security code is ready for downloading by sending a “security code ready” message to the cardholder. On receiving a transaction from the cardholder with an included a second security code, the security code is verified against the current, that is, the presently unexpired, security code.