French government’s end-to-end encrypted, open source messaging app Tchap was created by the French government to keep their officials, parliamentarians and ministers data on servers inside the country. The app is built using the Riot client, an open source instant messaging software that implements self-hostable Matrix protocol. A French security researcher who is better known by his Twitter username Elliot Alderson, found a security loophole that could allow anyone to sign up an account with the app without requiring an official email address.
Source: https://thehackernews.com/2019/04/france-Tchap-secure-messenger.html