On October 6, 2019, a pro-Islamic State (ISIS) tech group on Telegram, which is dedicated to educating Muslims on issues related to communication security, information technology, and online safety and privacy, posted on Telegram links to their Rocket Chat and Telegram channels. In the post they noted that end-to-end encryption is now active on Rocket.Chat and can also be used for chatrooms. The post also has a link to Rocket.Chat's user guide on end-to-end encryption.
Source: Telegram, October 6, 2019.