PostPref: A Facebook App to Help Manage Photo Privacy

A number of years ago, Daniel Howe and Helen Nissenbaum at New York University developed and released TrackMeNot, a lightweight Firefox browser extension that protects users against search data profiling by issuing randomized queries to popular search-engines with fake data. TrackMeNot obscures users’ actual search trails in a cloud of ‘ghost’ queries, significantly increasing the difficulty of aggregating such data into accurate or identifying user profiles. I like to refer to it as “polluting your data cloud.”

TrackMeNot represents a form of technological resistance in the fight against the increasing loss of control individuals posses over their online personal information flows, and I was excited to play a very small role in its development while at NYU. Now, five years later, NYU has a thriving Privacy Research Group, filled with “students, professors, and industry professionals who are passionate about exploring, protecting, and understanding privacy in the digital age.”

Recently, two members of the NYU Privacy Research Group, Jaime Madell and Ian Spiro, have launched another privacy-enhancing technology, this time targeted at empowering Facebook users. Their creation is PostPref, a Facebook application that helps users protect the privacy of their photos.

PostPref is an attempt to remedy the lack of context on online social networks, the architectures of which tend to weaken norms of information flow by forcing the “binary” (private vs. non-private) categorization of shared information. Simply put, PostPref is a photo watermarking tool that allows users to quickly and intuitively label their photos so that others know whether they should feel free to redistribute the photos.

The concept is pretty simple: Once you authorize the PostPref app on Facebook, you have the ability to add a red, yellow, or green light, and accompanying message, to each of your photos: A “green” mark means “feel free to re-post freely.” A “yellow” mark means “please ask me first before sharing.” And a “red” mark means “do not share this photo at all!” Below is an image of myself tagged with a yellow watermark, indicating that my permission should be requested before reposting the photo.

Of course, there’s no technical restriction on what others actually can do with these photos. Anyone who has access to your photos on Facebook could download a “red light” photo and use it as they wish. (They might want to crop out the watermark to avoid making their breach of your privacy wishes obvious).

But PostPref is a good step towards putting power back into the hands of users. Facebook consistently misunderstands the nature of privacy online, and tools like PostPref help reorient services like Facebook to better respect the complex nature of privacy online.

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