How TLS 1.3 0-RTT resumption actually works on the wire, why replay attacks make it risky for non-idempotent requests, and the patterns real teams use to deploy it safely behind NGINX, Envoy, and HAProxy.
Introduction If you put anything on the internet—an API, a website, an admin portal—you need SSL/TLS. It’s what turns http into https, encrypts traffic, and lets users verify they’re talking to the right server. But “turn on TLS” hides a lot of complexity: ciphers, certificates, OCSP, mTLS, key rotation, HTTP/2, QUIC, and more. This in-depth, zero-to-hero guide demystifies SSL/TLS. You’ll learn the concepts, how the protocol works, how to issue and deploy certificates, how to configure popular servers securely, how to test and monitor, and how to avoid common pitfalls. By the end, you’ll be able to ship production-grade TLS with confidence. ...