Factbox-What to know about Signal messaging app used by Trump aides to share war plans

(Reuters) – Top Trump administration officials used messaging app Signal to share war plans and mistakenly included a journalist in the encrypted chat, spurring calls by Democratic lawmakers for a congressional investigation into the security breach.

Under U.S. law, it can be a crime to mishandle, misuse or abuse classified information, though it is unclear whether those provisions might have been violated in this case.

Below are some of the main facts about Signal:

HOW DOES SIGNAL WORK?

Signal is a secure messaging service that uses end-to-end encryption, meaning the service provider cannot access and read private conversations and calls from users on its app, therefore guaranteeing its users’ privacy.

Signal’s software is available across platforms, both on smartphones and computers, and enables messaging, voice and video calls. A telephone number is necessary to register and create an account.

Unlike other messaging apps, Signal does not track or store user data, and its code is publicly available, so security experts can verify how it works and ensure it remains safe.

HOW SAFE IS IT?

Signal is an open-source and fully encrypted messaging service that runs on centralised servers maintained by Signal Messenger.

The only user data it stores on its servers are phone numbers, the date a user joined the service, and the last login information.

Users’ contacts, chats and other communications are instead stored on the user’s phone, with the possibility of setting the option to automatically delete conversations after a certain amount of time.

The company uses no ads or affiliate marketers, and doesn’t track users’ data, as stated on its website.

Signal also gives users the possibility to hide their phone number from others and use an additional safety number to verify the safety of their messages, it adds.

Signal does not use U.S. government encryption or that of any other governments, and is not hosted on government servers.

“All indications point towards Signal as one of the most trusted and secure services for communication,” said PP Foresight analyst Paolo Pescatore. “This is clearly underlined by the use within the U.S. government.”

WHO FOUNDED SIGNAL?

Signal was founded in 2012 by entrepreneur Moxie Marlinspike and its current president is Meredith Whittaker, according to the company’s website.

In February 2018, Marlinspike alongside WhatsApp co-founder Brian Acton started the non-profit Signal Foundation, which currently oversees the app. Acton provided an initial funding of $50 million. Acton left WhatsApp in 2017 due to differences around the use of customer data and targeted advertising.