Secure Hypertext Transfer Protocol
Secure hypertext transfer protocol (S-HTTP) is an alternative mechanism to the https: URI scheme for encrypting web communications carried over HTTP. S-HTTP is defined in RFC 2660.
Web browsers typically use HTTP to communicate with web servers, sending and receiving information without encrypting it. For sensitive transactions, such as Internet e-commerce or online access to financial accounts, the browser and server must encrypt this information. The https: URI scheme and S-HTTP were both defined in the mid 1990s to address this need. Netscape and Microsoft supported https: rather than S-HTTP, leading to https: becoming the de facto standard mechanism for securing web communications. S-HTTP is an alternative mechanism that is not widely used.