Secure Hypertext Transfer Protocol

Secure Hypertext Transfer Protocol (S-HTTP) is an obsolete alternative to the HTTPS protocol for encrypting web communications carried over HTTP. It was developed by Eric Rescorla and Allan M. Schiffman, and published in 1999 as 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. HTTPS and S-HTTP were both defined in the mid-1990s to address this need. S-HTTP was used by Spyglass's web server, while Netscape and Microsoft supported HTTPS rather than S-HTTP, leading to HTTPS becoming the de facto standard mechanism for securing web communications.