TLS (Transport Layer Security)

What is TLS?

Transport Layer Security (TLS) is a cryptographic protocol that provides secure communication over computer networks. It's the successor to SSL and is used to secure web traffic (HTTPS), email, messaging, and other communications.

TLS Provides

Confidentiality Encryption prevents eavesdropping.

Integrity Detect data tampering.

Authentication Verify server (and optionally client) identity.

TLS Handshake

1. Client Hello

   • Supported versions
   • Cipher suites
   • Random number

2. Server Hello

   • Selected version/cipher
   • Certificate
   • Random number

3. Key Exchange

   • Establish shared secret
   • Generate session keys

4. Finished

   • Verify handshake
   • Begin encrypted communication

TLS Versions

TLS 1.3 Improvements

• Faster handshake (1-RTT)
• Removed weak ciphers
• Forward secrecy required
• Encrypted handshake

Certificate Types

• Domain Validation (DV)
• Organization Validation (OV)
• Extended Validation (EV)
• Wildcard certificates
• Multi-domain (SAN)

Best Practices

• Use TLS 1.2+ only
• Prefer TLS 1.3
• Strong cipher suites
• Valid certificates
• HSTS headers
• Regular certificate rotation