SSL/TLS Handshake Simulator
Visualize how SSL/TLS handshakes work with certificate verification, key exchange, and cipher negotiation. Compare TLS 1.2 and 1.3 protocols.
Category: Security
Topics covered: security, networking, tls, ssl, certificates, educational
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SSL/TLS Handshake Simulator
Visualize how SSL/TLS handshakes work with certificate verification, key exchange, and cipher negotiation. Compare TLS 1.2 and 1.3 protocols.
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
- TLS 1.3: Latest version with 1-RTT handshake, mandatory PFS, and removed insecure algorithms.
- TLS 1.2: Still widely used, 2-RTT handshake with optional PFS.
- TLS 1.0/1.1: Deprecated, should not be used due to security vulnerabilities.
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.
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