Researchers hide censored files in Flickr photos

 

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By Nicole Kobie

Posted on 16 Jul 2010 at 15:12

Researchers have come up with a way to hide files in user-generated content in order to let people in heavily censored countries share materials.

Sam Burnett, a researcher at Georgia Tech, is to unveil the Collage system in a paper next month. It lets users hide files – such as a blog post or email – inside another file and publish it on sharing sites so others can retrieve it, without having to set up proxies or take the usual security precautions.

“The idea we came up with is to use the fact that you have tonnes of content that could be used to host these censored documents, and use the fact that censors are going to be less likely to block more popular websites,” Burnett told PC Pro.

It’s taking the existing photos that people publish on Flickr and using them for dual purposes

“It’s taking the existing photos that people publish on Flickr, or using the existing videos that people publish on YouTube, and using them for dual purposes. People can look at the pictures and watch the videos, but they can also use them to store censored content," he explained.

Photo encoding

Burnett said there were many ways such a system could work, but the method the paper addresses would see users donate images via Flickr. Rather than upload the pictures directly to Flickr, they would be run through the system where documents would be encoded inside them, before being posted to the photo-sharing site.

To retrieve the hidden files, a user would have to locate specially tagged photos and run them through the decryption software. If the message was particularly short, it could be embedded in only one or a small number of photos, with the link(s) shared around.

A censoring country could counter the system by blocking the entire site, but that would be difficult to achieve, draw media attention, and the host content could simply be moved to a different site. Censors could also ask sites to scrub out the additional content on the uploaded images, but that would require the site's co-operation.

Burnett expects to release the software next month. It will be open source in order to let developers create similar systems for sites other than Flickr.