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Deepfake App Zao Makes You a Movie Star. But It Also Raises Big Privacy Concerns

In a matter of seconds, Zao, a Chinese app that's gained huge momentum in a short amount of time, lets users blend their faces onto their favorite actors—putting themselves into some of their favorite movie and TV scenes.

While the app is intended to be fun, it also gives average people the tools for creating deepfake videos. The technology alters scenes from popular movies and TV shows to stitch a user's face onto the original actor's in a scene, instantly turning Leonardo DiCaprio into someone else. Right now, all that is required to create a deepfake video using Zao is a smartphone and a Chinese phone number.

The app, which was created by a subsidiary of Chinese developer Momo, has exploded in popularity since it was released last week. It's the No. 1 free app downloaded in China, according to the latest rankings from analytics company App Annie.

Users choose a scene and then upload their image, along with video showing head movements. In a few seconds, that photo is added to the faces of popular actors in TV shows, such as Game of Thrones and Big Bang Theory, and a selection of Chinese movies.

Allan Xia, a game developer based in New Zealand, shared an example showing his face on Leonardo DiCaprio's body that looks convincing.

Momo did not immediately respond to a request from Fortune for more information about the app and whether it would be released in the United States.

An online search surfaces various tools offering anyone the chance to create their own deepfake videos, whether it's a horrifying mash-up of Jennifer Lawrence and Steve Buscemi, a villainous Facebook CEO Mark Zuckerberg appearing to brag, "whoever controls the data, controls the future," or altering what President Obama is saying to prove a point.

While some deepfakes seem rudimentary, the ease of use and the speed the videos can be produced raises concerns about how they could be used to blur the truth online.

Are users trading their facial data to use the app?

Zao's oernight success has raised concerns among privacy critics about who owns a person's image —and what is being done with it—after they feed it to the app. The red flags being raised are similar to the scrutiny another face-swapping app, FaceApp, dealt with in July.

FaceApp had another viral moment during the #OldAgeChallenge, when people would take a selfie and run it through the app's filter to show what they'll look like in old age. It seems like all fun and games, but the app's Russian ties and vague privacy policy raised concerns, drew criticism, and even prompted Sen. Chuck Schumer to call on the FBI to investigate.

FaceApp offered users what it says is a process to delete their information, if they choose to do so. Wireless Labs, the owner of FaceApp, also clarified its privacy policy and the process it says it uses for uploading photos and generating various fun images for people, ranging from gender-bending to old age filters. (FaceApp founder Yaroslav Goncharov has previously apologized for a filter that lightened users' skin.)

Zao has faced similar questions about its terms of service during its meteoric rise. The company initially reserved broad rights to use images, but later amended its policy to state that it wouldn't use content without a user's consent, according to news site RADII China. Furthermore, if a person deletes the Zao app, then the company says their images and those Leonardo DiCaprio mash-ups they created will also be sent to the trash bin, supposedly to never be seen again.

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