Signal blocks Windows Recall’s all-seeing AI screenshots with a clever DRM hack

Signal has become a go-to chat and communications platform for users who want the peace of mind of secure, end-to-end encryption. It’s recently gotten a lot of free publicity thanks to some questionable applications of its tech, but the company has never wavered in its dedication to privacy. Following that mantra, Signal is blocking functionality for the new Windows Recall.

Windows Recall is one of the most visible and divisive features of Windows on enhanced “Copilot+” PCs, taking screenshots every few seconds and allowing the user to search through a history of their own activity. It’s certainly interesting tech, but it’s also a privacy nightmare, which is part of the reason Microsoft delayed its rollout for the better part of a year. Initially intrigued, PCWorld’s Mark Hachman now recommends that you turn Recall off as Microsoft rolls out the full version to millions of users.

The developers of Signal appear to agree with Mark. The latest version of the Windows app will simply appear as a blank black window if you try to record its activity with Windows Recall. It’s similar to the implementation of DRM in streaming services — you might have tried to take a screenshot of a Netflix show, only to get a blank black screen.

Signal is using built-in functionality in Windows and Recall, working as intended. Any developer can flip that DRM switch and keep Recall from recording its activity by default. “Apps like Signal have essentially no control over what content Recall is able to capture, and implementing ‘DRM’ that works for you (not against you) is the best choice that we had,” explains Signal developer Joshua Lund.

This isn’t without complications. Accessibility tools, such as magnifiers or text-to-speech readers, rely on the same sort of automatic screenshot functionality to help visually impaired users. With this in mind, the Signal app has an option to turn the screen security feature off (Settings>Privacy>Screen security). Users will have to click a verification when turning the setting off, but disabling that should allow Windows Recall to record Signal just like any other Windows app.

Lund didn’t pull any punches in the announcement post, with harsh words for Microsoft. In fact his criticisms are so good I’m just going to let him close out this article:

“Take a screenshot every few seconds” legitimately sounds like a suggestion from a low-parameter LLM that was given a prompt like “How do I add an arbitrary AI feature to my operating system as quickly as possible in order to make investors happy?” — but more sophisticated threats are on the horizon…It’s ultimately up to companies like Microsoft to ensure that their platforms remain a suitable foundation for privacy-preserving applications like Signal. If that ever stops being the case, we’ll have to stop supporting those platforms.”