NOISE

Network Operations and Internet Security @ Princeton

Collage

 Defeating Censorship with User-Generated Content

Oppressive regimes and even democratic governments restrict Internet access. Existing anti-censorship systems often require users to connect through proxies, but these systems are relatively easy for a censor to discover and block. This project offers a possible next step in the censorship arms race: rather than relying on a single system or set of proxies to circumvent censorship firewalls, we explore whether the vast deployment of sites that host user-generated content can breach these firewalls. We have developed Collage, which allows users to exchange messages through hidden channels in sites that host user-generated content. Collage has two components: a message vector layer for embedding content in cover traffic; and a rendezvous mechanism to allow parties to publish and retrieve messages in the cover traffic. Collage uses user-generated content (e.g., photo-sharing sites) as “drop sites” for hidden messages.  To send a message, a user embeds it into cover traffic and posts the content on some site, where receivers retrieve this content using a sequence of tasks. Collage makes it difficult for a censor to monitor or block these messages by exploiting the sheer number of sites where users can exchange messages and the variety of ways that a message can be hidden. Our evaluation of Collage shows that the performance overhead is acceptable for sending small messages (e.g., Web articles, email).

Applications use Collage to send and receive messages, by hiding these messages inside user-generated cover content (e.g., images, tweets, etc.) and publishing them on user-generated content hosts like Flickr or Twitter. At the receiver, Collage fetches the cover content from content hosts and decodes the message. By hiding data inside user-generated content as they traverse the network, Collage escapes detection by censors.

You can send us email at coll@gtnoise.net. (Click ellipsis to get full address, or just take an educated guess.)

Demo Application

We have released an application demonstrating Collage. Right now, it is only recommended for use on Ubuntu Linux. Support for other systems will be coming in the next few days.

Click here to try out the demo application.

Photo Donation

We have put a photo donation service online, which lets you donate your Flickr photo album to help fight censorship. Click here fore more information.

Source Code

Collage’s source code is hosted on github.

Publications

Talks

USENIX Security 2010, Chipping Away at Censorship Firewalls with User-Generated Content. August 13, 2010.

In the Press and on the Web

M. Cooney, Researchers tout new weapon in Internet censorship arms race. Layer 8, Network World. July 9, 2010.
Nicole Kobie, Researchers hide censored files in Flickr photos. PC Pro. July 16, 2010.
Jim Giles, Hiding files in Flickr pics will fool Web censors. NewScientist. August 9, 2010.
Getting around Web censors with Flickr. Slashdot. August 15, 2010.
Ryan Paul, Beat censorship by hiding secret messages in Flickr photos. Ars Technica. August 18, 2010.
Hidden Truths: A new way of beating the web’s censors. The Economist. October 12, 2010.
M. Cooney, Researchers tout new weapon in Internet censorship arms race. Layer 8, Network World. July 9, 2010.
Internet Censorship Arms Race Gets New Weapon From Georgia Tech. Slashdot. July 9, 2010.
Software Uses Twitter, Flickr to Let Dissidents Send Secret Messages. Gigaom. July 12, 2010.
Spy Tools to Spread Dissident Information. techchange. July 15, 2010.
Nicole Kobie, Researchers hide censored files in Flickr photos. PC Pro. July 16, 2010.
Dan Thornton, Sending secret messages through Twitter to avoid censorship. 140Char. July 17, 2010.
Jim Giles, Hiding files in Flickr pics will fool Web censors. NewScientist. August 9, 2010.
Justin Robinson, Avoid online censorship with ‘Collage’ and hide your data with Flickr. Atomic MPC. August 13, 2010.
David Murphy, Collage Combats Censorship by Hiding Text in Images. PC Magazine. August 15, 2010.
Getting around Web censors with Flickr. Slashdot. August 15, 2010.
Mike Masnick, New Program Makes It Even Easier To Hide & Access Information In Flickr Photos. Tech Dirt. August 16 ,2010.
Ryan Paul, Beat censorship by hiding secret messages in Flickr photos. Ars Technica. August 18, 2010.
Brenna Ehrlich, Viral Videos and Flickr Photos Could Help You Circumvent Censorship. Mashable. August 18, 2010.
Laurent Checola. Censure : une nouvelle parade pour les cyberdissidents. Le Monde. August 18, 2010.
Priyanka Boghani. Collage challenges Internet censorship. Index on Censorship. August 24, 2010.
Bennett Haselton, Collage, and the Challenge of “Deniability”. Slashdot. August 25, 2010.
Jake Edge, Thwarting internet censors with Collage. Linux Weekly News. September 1, 2010.
Hidden Truths: A new way of beating the web’s censors. The Economist. October 12, 2010.
Richard Bejtlich, Collage: Defeating Censorship [aka Security] with User-Generated Content. TaoSecurity blog. November 1, 2010.

People

Sam Burnett
Nick Feamster
Santosh Vempala

One thought on “Collage

  1. Pingback: Nick Feamster Lectures on Censorship at ETH Zurich Workshop | GT Noise

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