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An Optical Trick Makes Disappearing Messages Harder to Screenshot

An app called Yovo uses a clever trick to make it hard to preserve its ephemeral messages.
October 8, 2014

A new app called Yovo aims to make disappearing messages truly short-lived by foiling a recipient’s attempts to take screenshots.

How a Yovo image will appear if someone tries to take a screenshot.

Like Snapchat and other ephemeral-messaging apps, Yovo lets you send photos with notes on them that can be viewed for a limited amount of time before they self-destruct. But Yovo, available Wednesday and initially only for the iPhone, also includes a feature called D-fence that yields only an image interrupted by opaque vertical bars when you try to take a screenshot or a photo with another camera.

The free app was created by ContentGuard, a company that makes private document-sharing software. Scott Richardson, ContentGuard’s product head, says the company wanted to make a privacy-oriented app that is also social—somewhere between privacy-oriented apps like Wickr and Snapchat and apps like Instagram, where users post photos that are preserved and often available for anyone to see.

Richardson says the app’s makers realized early on that they needed a way to make images impervious to screen captures, because as long as a user can do that, the app remains “kind of leaky.”

Their solution takes advantage of visual perception, specifically the fact that you can clearly see what’s behind a slatted fence if you drive by at a certain speed. Photos sent through Yovo can be set to be viewable for as short as a second or as long as a day, and if you choose to use the D-fence filter on a photo shared through the app, the photo is interleaved with a virtual “fence” on the viewer’s end.

This fence moves across the image so quickly that it looks to you as if you’re seeing the full image, Richardson says, yet if someone takes a screen shot of a D-fenced image, or takes a photo of it with another camera, they’ll get an image with slats obscuring much of its content.

There are other image-obscuring options, too, such as the ability to blur images and decide who can see the blurred portion. Users can send images to people outside the app as well—if sent via e-mail, text, Facebook, or Twitter, a viewer would receive a URL that works once to see the image.

The D-fence filter still needs work: in a demo video the flickering fence line is definitely noticeable, but Richardson says a newer version is in the works for iOS and Android that runs at a higher frame rate and gives off only a faint flicker. He expects this to be available in the next month.

“It’s totally cool,” he says.

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