The Life of a TLS Handshake — TLS 1.3 Protocol in Full

A client fires off a 538-byte ClientHello stuffed with key agreement, version negotiation, ALPN, SNI, and a 0-RTT invitation. One round-trip later, HKDF grows eight keys out of a single root seed, the certificate chain is verified, the handshake self-attests via HMAC, and AEAD takes over every application byte — all in 1 RTT. A byte-level field manual for TLS 1.3, from ClientHello to ECH to post-quantum KEM.