What Is TLS?
TLS (Transport Layer Security) is the cryptographic protocol that secures internet communications. It provides privacy, data integrity, and authentication between communicating applications. TLS is the successor to SSL and is used for HTTPS, email (SMTP/IMAP), and many other protocols.
How It Works
TLS uses a combination of asymmetric and symmetric cryptography. During the handshake, the client and server use public-key cryptography to authenticate and agree on a shared secret. This secret is then used for symmetric encryption of the actual data, which is much faster.
Why It Matters
TLS protects sensitive data from eavesdropping and man-in-the-middle attacks. Using outdated TLS versions (1.0, 1.1) exposes your service to known vulnerabilities. TLS 1.2 is the minimum recommended; TLS 1.3 offers improved security and performance.
Common Issues
- Using deprecated TLS 1.0 or 1.1
- Weak cipher suites enabling attacks
- TLS handshake failures from misconfiguration
- Certificate chain issues breaking TLS