Signal is planning to launch an upgraded secure group messaging and communities function. Signal’s groups are private, meaning that the service itself doesn t keep a record of a user s group memberships, group titles, group avatars or group attributes. But the way the privacy controls have been implemented have raised a few usability issues, including users having access to disparate group states and it precludes role-based access control. Signal said it has worked with Melissa Chase and Greg Zaverucha from Microsoft Research to extend their keyed-verification concept.
Source: https://threatpost.com/signal-upgraded-cryptography-groups-function/151017/