Would you send a selfie to Facebook to prove who you are? That could be the future of online authentication — at least according to a recent test spotted by some users of the social network.

Confirmed by Facebook itself, the feature acts as a Captcha test. Where current Captcha systems ask the user to prove they are human by clicking a checkbox or answering a simple math question, Facebook asks for a clear and freshly taken photograph of your face.

Captcha stands for Completely Automated Public Turing test to tell Computers and Humans Apart. In this case, the system is primarily being used to verify that Facebook accounts are being used by real people and not computers attached to a botnet.

Reports of the verification system, which is currently being trialed in a small number of cases, was first spotted by Facebook users back in April. Some reported on Reddit that they would be locked out of their Facebook account for several hours while the photo they uploaded is verified.

This week, Facebook has confirmed what it is doing, telling Wired the photo test is intended to "help us catch suspicious activity at various points of interaction on the site, including creating an account, sending friend requests, setting up ads payments, and creating or editing ads."

The process of both recognizing suspicious behavior and verifying the photograph are automated, Facebook says, adding that the system looks to see if the photo uploaded as verification is new and unique, or already exists online. Using a preexisting image which Facebook finds during its search would fail the Captcha test.

A screenshot of the verification system, posted on Twitter, reads: "Please upload a photo of yourself that clearly shows your face. We'll check it and then permanently delete it from our servers."

Another, now deleted, post suggested that users are locked out of their Facebook account while the image is being analyzed. It read: "You can't log in right now. We'll get in touch with you after we've reviewed your photo. You'll now be logged out of Facebook as a security precaution."

One Reddit user claimed the system had locked them out of their Facebook account for 12 hours. Once they were let back in, they were kicked out again after just 30 minutes, they said.

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