Twitter is testing an end-to-end encrypted messaging feature on Android app for Android users. The Secret Conversation feature has been spotted in the latest version of Android application package (APK) for Twitter by Jane Manchun Wong, a computer science student at the University of Massachusetts Dartmouth. Secret Conversation appears to allow Twitter users to send encrypted direct messages and beef up the security of their conversation. Twitter is also working on an in-app mode, which if enabled, saves some of your bandwidth and speeds up the app.
Source: https://thehackernews.com/2018/05/encrypted-twitter-direct-messages.html