The Secure Socket Layer (SSL) protocol is used between a web server and client and provides entire session encryption, thus preventing from session hijacking. RSA is asymmetric encryption algorithm that can be used in setting up a SSL session. SET is the Secure Electronic Transaction protocol that was introduced by Visa and Mastercard to allow for more credit card transaction possibilities. PPP is a point-to-point protocol. Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, John Wiley & Sons, 2001, Chapter 3: Telecommunications and Network Security (page 89).