SSL vs TLS: What's the Difference?
A comprehensive guide to understanding SSL and TLS protocols
The Short Answer
TLS (Transport Layer Security) is the modern successor to SSL (Secure Sockets Layer). They serve the same purpose: encrypting data between a client and server. SSL is deprecated and should not be used. When people say "SSL certificate," they almost always mean a certificate used with the TLS protocol.
A Brief History
SSL was developed by Netscape in the 1990s. SSL 2.0 was the first publicly released version (1995), followed by SSL 3.0 (1996). TLS 1.0 was introduced in 1999 as a standards-based upgrade. TLS 1.1 arrived in 2006, TLS 1.2 in 2008, and TLS 1.3 in 2018. All SSL versions and TLS 1.0/1.1 are now deprecated due to known vulnerabilities.
Key Differences
- Security - TLS uses stronger cryptographic algorithms and eliminates vulnerabilities present in SSL.
- Performance - TLS 1.3 reduces handshake roundtrips, making connections faster.
- Cipher Suites - TLS 1.3 removes support for legacy algorithms like RC4, DES, and 3DES.
- Compatibility - Modern browsers require TLS 1.2 or higher. SSL connections will be rejected.
Why Do People Still Say "SSL"?
The term "SSL" became the generic name for web encryption. Even though TLS replaced SSL over 20 years ago, "SSL certificate" remains the common term. The certificates themselves work with any protocol version - they are not specific to SSL or TLS.
What Should You Use?
Always use TLS 1.2 or TLS 1.3. Disable all SSL versions and TLS 1.0/1.1 on your server. Modern web servers default to secure settings, but older configurations may still have legacy protocols enabled.