OhMyECH - ECH Indicator от 27justin

This extension adds an icon to Firefox’s address bar which indicates whether this page used Encrypted-Client-Hello (ECH) or not.

ECH is a extension to TLSv1.3 which encrypts the TLS Client-Hello. Before ECH any middle-man between your PC and the server was able to read out the SNI (Server-Name-Indication), i.e. the domain you were visiting.

The extension displays a green/red-lock to the right side of your address bar, similar to the HTTP(S) lock.

The source code for this extension is available at https://github.com/27justin/ohmyech