Online personalization of terminals (OPT) is a procedure to increase the security of credit card payments. It is a procedure prescribed by the Central Credit Committee
(ZKA) with which highly sensitive bank and account data for money transfers are secured. The security procedure standardized by the ZKA for the entry of
sensitivedata at ATMs and POS terminals serves to ensure the security of the data entered by the customer and transmitted to the credit institution. In the OPT procedure, the data is encrypted in a triple DES encry ption (3DES) and the messages are secured with a MAC code. This makes it impossible to spy out or manipulate the data. Cryptographic keys
can be renewed using the OPT process. To secure the transactions made at the OPT terminal, all transactions are provided with their own individual identity and a time stamp and stored. This makes it possible to check all activities without gaps at a later date.