SSL - Secure Sockets Layer
SSL (pronounced as separate letters) is short for Secure Sockets Layer.
Secure Sockets Layer (SSL) is a protocol developed by Netscape for transmitting private documents via the Internet. SSL uses a cryptographic system that uses two keys to encrypt data − a public key known to everyone and a private or secret key known only to the recipient of the message.
Most Web browsers support SSL, and many websites use the protocol to obtain confidential user information, including credit card numbers. By convention, URLs that require an SSL connection start with https: instead of http:.
How SSL Works
When a Web browser tries to connect to a website using SSL, the browser will first request the web server identify itself. This prompts the web server to send the browser a copy of the SSL Certificate. The browser checks to see if the SSL Certificate is trusted -- if the SSL Certificate is trusted, then the browser sends a message to the Web server. The server then responds to the browser with a digitally signed acknowledgement to start an SSL encrypted session. This allows encrypted data to be shared between the browser and the server. You may notice that your browsing session now starts with https (and not http).
Secure HTTP (S-HTTP)
Another protocol for transmitting data securely over the World Wide Web is Secure HTTP (S-HTTP). Whereas SSL creates a secure connection between a client and a server, over which any amount of data can be sent securely, S-HTTP is designed to transmit individual messages securely. SSL and S-HTTP, therefore, can be seen as complementary rather than competing technologies. Both protocols were approved by the Internet Engineering Task Force (IETF) as a standard.
SSL 3.0 Vulnerable and Obsolete
SSL version 3.0 is based on the 1996 draft. In 2014, the 3.0 version of SSL was considered vulnerable due to POODLE (Padding Oracle On Downgraded Legacy Encryption) attacks. These attacks allowed secure HTTP cookies or HTTP Authorization header contents to be stolen from downgraded communications. Today, SSL 3.0 is considered obsolete and has been succeeded by Transport Layer Security (TLS), but it is still widely deployed.
Going From SSL to TLS
Secure Sockets Layer (SSL) is the predecessor to Transport Layer Security (TLS). TLS is an Internet Engineering Task Force (IETF) standards track protocol that is based on the earlier SSL specifications.
Recommended Reading: Learn more about Transport Layer Security (TLS) in this Webopedia definition.
Stay up to date on the latest developments in Internet terminology with a free weekly newsletter from Webopedia. Join to subscribe now.
From A3 to LOL and ZZZ this guide lists 1,500 text message and online chat abbreviations to help you translate and understand today's texting... Read More »SEO Dictionary
From keyword analysis to backlinks and Google search engine algorithm updates, our search engine optimization glossary lists 85 SEO terms you need... Read More »Slideshow: History of Microsoft Operating Systems
Microsoft Windows is a family of operating systems for personal computers. In this article we look at the history of Microsoft operating... Read More »
Learn about each of the five generations of computers and major technology developments that have led to the computing devices that we use... Read More »Computer Architecture Study Guide
Computer architecture provides an introduction to system design basics for most computer science students. Read More »Network Fundamentals Study Guide
Networking fundamentals teaches the building blocks of modern network design. Learn different types of networks, concepts, architecture and... Read More »