Advanced Topics

Site Certificates

issued by a trusted service, these digital signature-based certificates are sent by a server to prove that it is who it purports to be; that is, that it really is (eg) http://amazon.com and not http://hackers-r-us.com masquerading as them.
 

Secure Sockets Layer

SSL is a public key encryption system. A server can publish its public key in association with its site certificate. The public key can then be used to communicate securely. You can tell if a server uses SSL for a document if the URL starts with https://... Also, if you're using Netscape, the little "key"or padlock icon will change. On the other hand, encryption is computationallyheavy, so it's typically not used for normal Web pages.