SSL/TLS Handshake Simulator - Learn Secure Connection Establishment
How to use this simulator
Watch how your browser establishes a secure HTTPS connection. Use the Play button for auto-advance, or Next/Prev to step through manually. Each step shows what data is exchanged between client and server.
💡 Tip: Try different TLS versions and failure scenarios to see how the handshake changes.
SSL/TLS Handshake
Visualize how secure connections are established
ClientHello
Client initiates with key share
TLS 1.2
- • 2 round-trips (2-RTT) to establish
- • Supports older cipher suites
- • RSA key exchange still allowed
- • Separate ChangeCipherSpec message
- • Widely supported (legacy systems)
TLS 1.3Recommended
- • 1 round-trip (1-RTT) - 50% faster!
- • Only AEAD ciphers (more secure)
- • Perfect Forward Secrecy required
- • Encrypted earlier in handshake
- • 0-RTT resumption possible
Key Concepts
Cipher Suite
A combination of algorithms: key exchange (ECDHE), authentication (RSA/ECDSA), encryption (AES-GCM), and hashing (SHA256).
Perfect Forward Secrecy
Even if the server's private key is compromised, past sessions remain secure because each session uses unique ephemeral keys.
Certificate Authority (CA)
A trusted organization that issues digital certificates. Browsers have a list of trusted root CAs built-in.
AEAD (Authenticated Encryption)
Combines encryption and authentication in one step (e.g., AES-GCM). Required in TLS 1.3 for better security.
Understanding SSL/TLS Handshakes
What You'll Learn
- How TLS 1.2 and TLS 1.3 handshakes differ
- Certificate chain validation process
- Key exchange mechanisms (RSA, ECDHE)
- Cipher suite negotiation
- Common TLS failure scenarios
- Perfect Forward Secrecy (PFS)
TLS Versions
🔐 Key Concepts
- • Certificate: Digital document that binds a public key to an identity
- • Cipher Suite: Set of algorithms for encryption, authentication, and key exchange
- • PFS: Ensures session keys aren't compromised even if server's private key is
- • AEAD: Authenticated Encryption with Associated Data (e.g., AES-GCM)
🎯 Best Practices
- • Use TLS 1.3 where possible, TLS 1.2 as minimum
- • Disable weak cipher suites (RC4, DES, export ciphers)
- • Enable HSTS to prevent protocol downgrade attacks
- • Keep certificates up to date and use short validity periods
- • Use Certificate Transparency (CT) logging