The office of Frank Larkin, the Sergeant at Arms of the U.S. Senate, has approved encrypted messaging app Signal for official use, according to a letter from Oregon senator Ron Wyden. This news comes alongside a move toward end-to-end HTTPS encryption on all Senate websites and allows full use of the encrypted app for all official communications. While the approval was actually granted back in March, Wyden's recent letter formally thanks Larkin for approving the app, and brings the approval into the public eye by way of a publicly available version of the letter on a document mirroring service. Signal automatically encrypts messages with no backdoor, as Wyden articulates in his letter, making it one of the safest methods of electronic communication over a mobile network that's accessible on a modern smartphone without serious tweaking.
Signal has found itself at the heart of the international conversation about cybersecurity in the past due to its fully encrypted approach to messaging, including rumors that it had been compromised by government entities. To this day, Signal remains encrypted by default, and uncracked by any known entities, making it one of the very few messaging apps out there that are fully secure out of the box and don't require any kind of setup. It does, however, require both ends of a message to pass through the Signal app, meaning that it can't be used for encrypted conversations through other apps, or protocols like SMS. According to its Play Store listing, Signal is also the only fully open source app of its kind, which uses fully peer-reviewed security protocols. Signal's own servers don't have access to metadata, meaning that encryption and decryption happen only on the two devices involved in the conversation.
Signal received an update not too long ago that included secure video calls, making it one of the more feature-rich encrypted messaging apps out there. There are multiple other options that the Senate could potentially have gone with, including Facebook Messenger, which rolled out encrypted private conversations last year, along with Silence, which uses similar protocols to Signal to encrypt SMS and MMS messages, and Telegram, which wound up in the midst of a controversy last year when it was allegedly used for acts of terrorism.