New tool promises private photo sharing


LOS ANGELES — In the next five minutes, roughly a half-million photos will be shared online.

Embarrassing or not, many are only intended for a certain audience — family, or friends maybe — not the whole world. And yet, relatively few will be encrypted, leaving them vulnerable to simple data harvesting.

Thanks to a new tool developed by a research team at the University of Southern California, that could all be about to change.


The tool, dubbed “P3” for “Privacy-Preserving Photo Sharing” removes small amounts of crucial data from a photo and encrypts them, allowing cloud file-sharing services like Facebook and Flickr to have only the unencrypted — but now unrecognizable — portion.

The photo’s owner can then choose to share the encrypted portion with other parties — allowing them to see the whole picture — without ever uploading it to the cloud.
If the whole photo is encrypted, Facebook and Flickr cannot resize it, making the photo unusable.

However, with P3 such cloud file-sharing services can use the unencrypted portions of the photo (which are degraded beyond recognition) to resize it for viewing on multiple devices.

The tool is the brainchild of Antonio Ortega and Ramesh Govindan, both professors at the USC Viterbi School of Engineering. They collaborated with USC Ph.D. student Moo-Ryong Ra on the project.

Cloud-based sharing

“Nobody doubts the convenience of cloud-based sharing, the question is whether we can trust third parties to protect our photos from unauthorized distribution or use,” Ortega said.

“With P3 you decide how your photos can be used, without losing the convenience of sharing them on through the cloud.”

In addition to ensuring privacy, the tool also allows the photo’s owner to retain the rights to the photo. When you upload a photo to Facebook, for example, its Statement of Rights and Responsibilities indicates it has a non-exclusive license to use that photo until you delete your account (provided that the photo hasn’t already been shared with another person whose account is still active).

Retaining the rights

With P3, Facebook still retains the rights to the portion of the photo that you’ve uploaded — but that portion is a degraded, unrecognizable mess. Only you retain the rights to the complete photo.

P3 is already protected under a provisional patent, and Ortega and Govindan plan to launch a company this summer.


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