Signal CEO Steps Down, Replaced By WhatsApp Co-founder

Moxie Marlinspike resigns as CEO of Signal, with WhatsApp co-founder Brian Acton taking over as interim chief executive in the meantime

Signal co-founder and CEO Moxie Marlinspike (aka Matthew Rosenfeld) has announced his resignation, after working at the encrypted messaging service for over ten years.

He will be replaced by Brian Acton, currently the Signal Foundation’s executive chairman, who steps in as interim chief executive until a permanent CEO is found. Acton of course is the co-founder of rival messaging service WhatsApp.

Marlinspike will transition from the CEO role over the next month, but will remain a board member of the Signal Foundation.

Stepping down

Marlinspike announced his decision on Monday in a blog post, entitled ‘new year, new CEO’.

“I have now been working on Signal for almost a decade,” he wrote. “It has always been my goal for Signal to grow and sustain beyond my involvement, but four years ago that would still not have been possible. I was writing all the Android code, was writing all of the server code, was the only person on call for the service, was facilitating all product development, and was managing everyone.”

“I couldn’t ever leave cell service, had to take my laptop with me everywhere in case of emergencies, and occasionally found myself sitting alone on the sidewalk in the rain late at night trying to diagnose a service degradation,” he added.

Marlinspike said that in the past four years he has been endeavouring to change that, and Signal is made up of “an amazing group of 30 people.”

“Simultaneously, Signal has grown in adoption and popularity around the world even faster than I imagined” he wrote. “In other words, after a decade or more, it’s difficult to overstate how important Signal is to me, but I now feel very comfortable replacing myself as CEO based on the team we have, and also believe that it is an important step for expanding on Signal’s success.”

“I will continue to remain on the Signal board, committed to helping manifest Signal’s mission from that role, and I will be transitioning out as CEO over the next month in order to focus on the candidate search,” he wrote.

“Brian Acton, who is also on the Signal Foundation board, has volunteered to serve as interim CEO during the search period,” he said. “I have every confidence in his commitment to the mission and ability to facilitate the team for this time.”

Marlinspike has helped Signal achieve more than 40 million users, and it experienced a major growth surge after changes to WhatsApp’s privacy policy caused some users to switch.

Such was the concern at the WhatsApp move at the time, that Signal began to be recommended by users such as Tesla CEO Elon Musk and NSA whistleblower Edward Snowden.

Cellebrite clash

Moxie Marlinspike in a prior life was the former head of the security team at Twitter, but left the platform in 2013.

He, along with Trevor Perrin then started developing the Signal Protocol, which eventually became Signal.

On 21 February 2018, Marlinspike and WhatsApp co-founder Brian Acton announced the formation of the Signal Technology Foundation, with $50m in funding from Acton.

In recent times Marlinspike rose to prominence in Signal’s clash with security specialist Cellebrite, after it astonished the security industry in December 2020 when it claimed it had cracked the encryption of Signal.

Signal is one of the most secure messaging apps on the market, and Cellebrite’s claim was quickly dismissed by Moxie Marlinspike, after it emerged that the exploit seemed to work via an unlocked Android phone.

Matters were not helped when Cellebrite significantly altered its original blog on the hacking claim, leading to question marks over the reliability of its original claim.

Marlinspike had his revenge in April 2021 however, when he revealed that he had hacked Cellebrite’s own hacking equipment and software, used by law enforcement to break into Android or iOS phones and allegedly extract secure messages.

Marlinspike said at the time that he and his team had managed to obtain a Cellebrite UFED, complete with the software and hardware dongle.

He joked that it fell off a truck while he was out for a walk.

Brian Acton

The interim CEO of Signal is Brian Acton, who was co-founder of WhatsApp

He left Facebook in November 2017, and was soon followed by Jan Koum in May 2018, after both men clashed with Facebook’s attempts to use its personal data and weaken its encryption.

Facebook of course acquired WhatsApp in 2014 for a staggering $22bn, despite the fact that WhatsApp at the time had a tiny revenue stream.

Acton in 2018 admitted that he had sold the privacy of WhatsApp users, and disagreements happened between him and Facebook boss Mark Zuckerberg and chief operating officer Sheryl Sandberg before he left the firm.

Since his departure, Acton then joined a number of former executives critical of Facebook and in 2018 he tweeted “it is time. #deletefacebook” following the Cambridge Analytica data sharing scandal.

Although the acquisition by Facebook made Acton a billionaire, he apparently departed Facebook before his final tranche of stock grants matured. That decision to leave before his grants matured is reported to have cost him $850m.

“At the end of the day, I sold my company,” Acton said. “I sold my users’ privacy to a larger benefit. I made a choice and a compromise. And I live with that every day.”