TM Signal is compatible with Signal and would expose messages sent in a chat with someone using TM Signal, whether all participants are using it or some are using the genuine Signal app. Lee found that TM Signal is designed to save Signal communication data in a local database on a user's device and then send this to an archive server for long-term retention. The messages, he says, are sent directly to the archive server, seemingly as plaintext chat logs in the cases examined by Lee. Conducting the analysis, he says, “confirmed the archive server has access to plaintext chat logs.”Data taken from the TeleMessage archive server in the hack included chat logs, usernames and plaintext passwords, and even private encryption keys. “They have given their users something that looks and feels like Signal, the most widely trusted secure communications app.