Good-bye ESNI, hello ECH!

What this post added

Introduces Encrypted Client Hello (ECH) as a successor to Encrypted SNI (ESNI). ECH encrypts the entire TLS handshake, protecting sensitive metadata like SNI and ALPN from network observers. It builds upon the lessons learned from ESNI and TLS 1.3's handshake encryption attempts, addressing key distribution challenges and the need for handshake parameters essential for authentication to be sent in the clear. ECH aims to enhance privacy and lay the groundwork for future security and performance features in TLS.