Visa and MasterCard have jointly developed the Secure Electronic Transaction (SET) protocol as a method for secure, cost effective bankcard transactions over open networks. SET includes protocols for purchasing goods and services electronically, requesting authorization of payment, and requesting ``credentials'' (that is, certificates) binding public keys to identities, among other services. Once SET is fully adopted, the necessary confidence in secure electronic transactions will be in place, allowing merchants and customers to partake in electronic commerce.
SET supports DES (see Section 3.2) for bulk data encryption and RSA (see Question 3.1.1) for signatures and public-key encryption of data encryption keys and bankcard numbers. The RSA public-key encryption employs Optimal Asymmetric Encryption Padding [BR94].
SET is being published as open specifications for the industry, which may be used by software vendors to develop applications.