The Secure Electronic Transactions (SET) protocol is an open, interoperable standard for Certificates are heavily used by SET, both for certifying a cardholder and for certifying that the merchant has a relationship with the financial institution. The mechanism is illustrated in Figure 19.11. While both Microsoft and Visa International are major participants in the SET specifications, they currently provide the Secure Transaction Technology (STT) protocol, which has been designed to handle secure bank payments over the Internet. STT uses DES encryption of information, RSA encryption of bankcard information, and strong
authentication of all parties involved in the transaction.