(Reuters) - Elon Musk's team working to dismantle the federal bureaucracy and the protesters hoping to stop him have something in common.

They use Signal to keep their communications secure.

Signal, a text-and-voice app that is a little over a decade old, is seen as the gold standard for end-to-end encrypted communications, according to mobile security experts. It has been widely adopted - not just by privacy-conscious dissidents but by officials, lawmakers, generals, and corporate leaders as well.

Even before the app became a national talking point when senior Trump officials inadvertently added a reporter to their sensitive discussions about impending airstrikes on Yemen, Signal was taking the capital by storm.

Data from Sensor Tower, an analytics firm, shows that U.S. app downloads of Signal in the first three months of 2025 are up 16% compared to the prior quarter and 25% compared to the same period in 2024.

In Washington, it is hard to find a congressional aide or political appointee who does not use the app, which is run by the nonprofit Signal Foundation. The words, "Let's take this to Signal," are the universal indication that the conversation is about to get interesting. A recent review by the Associated Press found more than 1,100 government officials across all 50 states on Signal.

Musk's Department of Government Efficiency is coordinating its government-cutting work over Signal, according to reports in the New York Times and the Wall Street Journal. Musk himself used the app during his 2022 purchase of the social media site Twitter and recently used the platform to talk to one of the mothers of his children, right-wing social media personality Ashley St. Clair.

GOVERNMENT APPROVAL

Some governments have officially blessed the use of Signal. In 2020, the European Commission told its staff to use Signal, adding that its guidance applied to "public instant messaging." U.S. officials have not been that explicit but, in guidance published late last year, the Cybersecurity and Infrastructure Security Agency urged senior government officials to immediately switch to end-to-end encrypted communications apps, of which Signal is among the most prominent.

The U.S. Senate has long approved Signal for use by legislative staffers.

Signal's privacy protections - the company says it captures only the bare minimum amount of data about its users - have also made it attractive to criminals.

Drug dealers routinely steer conversations with clients to Signal and other encrypted apps, the Drug Enforcement Agency said in a 2022 report, while the rioters who plotted to frustrate the peaceful transfer of power on January 6, 2021 used Signal to coordinate their attack on the U.S. Capitol, according to court filings that cited their chats.

The movement to oppose President Donald Trump's effort to dramatically downsize the federal bureaucracy and challenge longstanding constitutional protections is also taking place over Signal. Civil service whistleblowers are turning to Signal to avoid surveillance from Trump's appointees. Three recently fired employees told Reuters their colleagues have scrambled to download the app.

Some of the anti-Tesla protesters who have swarmed dealerships across the country after Trump's return to the presidency have also turned to the app, according to a person who is active in the movement.