Messaging app Signal is at the centre of questions about security and the operation of government after a journalist said he had been added to a group chat in which secret and official US plans were discussed.
Jeffrey Goldberg, the editor-in-chief of The Atlantic, said he had been added to a group chat on the messaging app hours before strikes on Houthi rebels in Yemen. In there US national security officials were discussing those strikes, he said.
Signal is less well known than some other competing messaging apps, such as Meta’s WhatsApp and Messenger or the iMessage app built into the iPhone. But it offers much the same features: a way to chat with contacts, through secure ways.
The National Security Council has since said the text chain “appears to be authentic" and that it is looking into how a journalist’s number was added to the chain.
Here's a look at how Signal works.
What is signal?
It's an app that can be used for direct messaging and group chats as well as phone and video calls.
Signal uses end-to-end encryption for its messaging and calling services that prevents any third-party from viewing conversation content or listening in on calls.
In other words, messages and calls sent on Signal are scrambled and only the sender and recipient at each end will have the key to decipher them.
Signal's encryption protocol is open source, meaning anyone that it's freely available for anyone to inspect, use or modify. The encryption protocol is also used by another popular chat service, social media company Meta's WhatsApp platform.
Encryption on Signal is turned on by default, unlike another popular messaging app, Telegram, which requires users to turn it on and does not make it available for group chats.
Signal has features that are found on other messaging apps. It allows users to host group chats with up to 1,000 people and messages can be set to automatically disappear after a certain time.
Is it secure?
Signal touts the privacy of its service — and experts agree it is more secure than conventional texting.
But it could be hacked.
Government officials have used Signal for organizational correspondence, such as scheduling sensitive meetings, but in the Biden administration, people who had permission to download it on their White House-issued phones were instructed to use the app sparingly, according to a former national security official who served in the administration.
The official, who requested anonymity to speak about methods used to share sensitive information, said Signal was most commonly used to notify someone that they should check for a classified message sent through other means.
Beyond concerns about security, Signal and other similar apps may allow users to skirt open records laws. Without special archiving software, the messages frequently aren’t returned under public information requests.
In the Atlantic article, Goldberg wrote that some messages were set to disappear after one week and some after four.
Is it easy to add people to a group?
Signal works much the same as other platforms: to add someone to a group, you need a mobile number or to have them as a contact. The actual act of adding them is relatively simple: a user clicks the group options, chooses “add members” and then picks the people they want to add, before being asked to confirm.
It is fairly easy to add someone to a group, therefore. It is also possible to see how you might accidentally add the wrong person, such as if they had the same first name as somebody else.
Who’s behind Signal?
The app's origins date back more than a decade, when it was set up by an entrepreneur who goes by the name Moxie Marlinspike, who was briefly head of product security at Twitter after he sold his mobile security startup to the social media company. Marlinspike merged two existing open source apps, one for texting and one for voice calls, to create Signal.
The nonprofit Signal Foundation was set up in 2018 to support the app's operations as well as “investigate the future of private communication,” according to the foundation's website. The foundation says it is a 501c3 nonprofit “with no advertisers or investors, sustained only by the people who use and value it.”
The foundation's board has five members, including Brian Acton, who cofounded WhatsApp and donated $50 million to set up the foundation.
Additional reporting by Associated Press
