TLS Handshake

ELI5 — The Vibe Check

The TLS handshake is the 'hello, do we trust each other?' ceremony that happens before any HTTPS data flows. The browser and server exchange certificates, agree on encryption methods, and swap keys. After the handshake, all data is encrypted. It takes a fraction of a second.

Real Talk

The TLS handshake establishes an encrypted session between a client and server. In TLS 1.3: the client sends supported cipher suites, the server selects one and sends its certificate, the client verifies the certificate and they derive session keys. TLS 1.3 completes in one round-trip.

Show Me The Code

# View TLS handshake details with curl
curl -v https://example.com 2>&1 | grep -E 'SSL|TLS|certificate'

# Check TLS version and cipher
openssl s_client -connect example.com:443

# Output shows:
# TLSv1.3, TLS handshake, Certificate
# SSL-Session: Protocol: TLSv1.3

When You'll Hear This

"The TLS handshake is failing because the certificate is expired." / "TLS 1.3 completes the handshake in one round trip."