What is Signal? The Messaging App Trump’s National Security Team Used For Sensitive Information

A magazine journalist’s unexpected inclusion in a group chat of U.S. national security officials has ignited concerns about the handling of sensitive government information.

Jeffrey Goldberg, Editor-in-Chief of The Atlantic, revealed that the discussion—held over the encrypted messaging app Signal—took place just hours before the U.S. launched airstrikes on Iran-backed Houthi rebels in Yemen.

Following the revelation, the National Security Council acknowledged the authenticity of the text chain and announced an internal review into how the journalist’s number ended up in the chat.

What Makes Signal Unique?

Signal is a widely used messaging app that supports direct messages, group chats, and phone and video calls. What sets it apart is its robust security: the app employs end-to-end encryption, ensuring that only the sender and recipient can access the conversation.

Unlike some messaging platforms, Signal enables encryption by default, even for group chats—something that rival app Telegram does not offer.

The app’s encryption protocol is open-source, meaning anyone can inspect and verify its security features. This same encryption technology is also used by WhatsApp, the messaging service owned by Meta.

Beyond encryption, Signal offers features such as disappearing messages, which can be set to erase conversations after a specified period, and support for large group chats of up to 1,000 users.

Is Signal Truly Secure?

While Signal is widely regarded as one of the most secure messaging apps, no platform is entirely hack-proof. Government officials have turned to Signal for quick and confidential communications, including scheduling sensitive meetings.

However, according to a former national security official from the Biden administration, White House staff were advised to limit their use of the app on government-issued phones.

“Signal was most commonly used to notify someone that they should check for a classified message sent through other means,” the former official explained. This suggests that while Signal is a secure tool, it is not the primary method for transmitting classified information.

Another concern with Signal—and similar encrypted messaging apps—is the potential for evading public records laws. Without archiving mechanisms, messages can disappear before they can be retrieved through official public information requests. Goldberg’s article in The Atlantic noted that messages in the group chat were set to disappear after either one or four weeks.

Signal’s Founders and Its Mission

The origins of Signal trace back more than a decade to its creator, Moxie Marlinspike, a security entrepreneur who briefly worked at Twitter after selling his mobile security startup to the company. Marlinspike combined two existing open-source apps—one for texting and another for voice calls—to develop Signal.

In 2018, the nonprofit Signal Foundation was established to sustain the app’s development and explore the future of private communication. The foundation operates without advertisers or investors and relies entirely on user donations. Among its key supporters is Brian Acton, co-founder of WhatsApp, who contributed $50 million to launch the foundation.

The Bigger Picture

Encrypted messaging apps like Signal are becoming more prevalent in government communications, with officials at all levels using them to discuss sensitive matters. A review by a leading news agency found that government personnel in nearly every U.S. state have registered accounts on such apps, with many using official government phone numbers.

As concerns over digital privacy and security grow, Signal remains a go-to platform for those seeking encrypted communication. However, as this recent controversy demonstrates, even the most secure tools can pose risks when used in unintended ways.

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