Technolgy Rules: Signal now has built-in face blurring for photos

Thursday, June 4, 2020

Signal now has built-in face blurring for photos

Apps like Signal are proving invaluable in these days of unrest, and anything we can do to simplify and secure the way we share sensitive information is welcome. To that end Signal has added the ability to blur faces in photos sent via the app, making it easy to protect someone’s identity without leaving any trace on other, less secure apps.

After noting Signal’s support of the protests occurring all over the world right now against police brutality, the company’s founder Moxie Marlinspike writes in a blog post that “We’ve also been working to figure out additional ways we can support everyone in the street right now. One immediate thing seems clear: 2020 is a pretty good year to cover your face.”

Fortunately there are perfectly good tools out there both to find faces in photographs and to blur imagery (presumably irreversibly, given Signal’s past attention to detail in these matters, but the company has not returned request for comment). Put them together and boom, a new feature that lets you blur all the faces in a photo with a single tap.

This is helpful for the many users of Signal who use it to send sensitive information, including photos where someone might rather not be identifiable. Normally one would blur the face in another photo editor app, which is simple enough but not necessarily secure. Some editing apps, for instance, host computation-intensive processes on cloud infrastructure and may retain a copy of a photo being edited there — and who knows what their privacy or law enforcement policy may be?

If it’s sensitive at all, it’s better to keep everything on your phone and in apps you trust. And Signal is among the few apps trusted by the justifiably paranoid.

All face detection and blurring takes place on your phone, Marlinspike wrote. But he warned that the face detection isn’t 100 percent reliable, so be ready to manually draw or expand blur regions in case someone isn’t detected.

The new feature should appear in the latest versions of the app as soon as those are approved by Google and Apple.

Lastly Marlinspike wrote that the company is planning “distributing versatile face coverings to the community free of charge”; the picture shows a neck gaiter like those sold for warmth and face protection. Something to look forward to, then.