SSL/TLS

SSL (Secure Sockets Layer) and TLS (Transport Layer Security) are cryptographic protocols that encrypt communication between two parties on the internet. TLS is the modern successor to SSL; when people say "SSL" today, they usually mean TLS. The protocol works through a handshake where the client and server agree on cipher suites and exchange keys, protecting against eavesdropping and tampering. RFC 8996 (2021) formally deprecated TLS 1.0 and 1.1, so TLS 1.2 is the practical floor (required by PCI DSS and modern browsers) and TLS 1.3 (RFC 8446) is the recommended target. Cloudflare errors 525 and 526 are caused by TLS problems between Cloudflare and the origin.