Microsoft® Windows® 2000 Security Handbook

Understanding SSL/TLS

In this chapter so far, I have discussed how Windows 2000 authenticates using NTLM. But you can also use SSL as you move across the Internet and get involved with electronic commerce. What is SSL/TLS (Secure Sockets Layer/Transport Layer Security), and how does itwork?

SSL was first introduced around 1994 with the Netscape Navigator browser. That same year, the S-HTTP protocol was introduced by a group called CommerceNet. The SSL protocol works at a lower level of the network than S-HTTP and can therefore be used to encrypt many different kinds of connections and not just HTTP.

SSL operates at the TCP/IP transport layer (offering transport-layer security), just below the application-specific type protocols such as HTTP