The good news is that MTProto, the message encryption protocol created by Telegram’s team and used both for regular conversations and “secret chats”, does not currently have known vulnerabilities. As opposed to Telegram’s MTProto, Signals end-to-end encryption protocol is widely considered the golden standard of secure encryption protocol design. All communication on Signal is end-to-end encrypted – there is simply no way available to send a message that is not fully end-to-end encrypted message on that service.