Why measure Web censorship?

Web censorship is a growing problem affecting users in an increasing number of countries. Collecting accurate data about what sites and services are censored will help educate users about its effects and shape future Internet policy discussions surrounding Internet regulation and control.

What is Encore?

Encore collects information about how Web users experience censorship. It causes every visitor to your Web site to attempt to access small pieces of data from other, potentially-censored Web sites, and sends us information about whether or not each visitor could access those censored sites. These measurements happen automatically in the background after your page has loaded and do not impact your site's performance or user experience; most users won't ever notice them or realize they are helping to measure Web censorship.

How do I install Encore on my site?

Add this line anywhere in the body of your page:

<iframe src="//encore.noise.gatech.edu/task.html" width="0" height="0" style="display: none"></iframe>

That's it! Your page's visitors will now collect measurements about how they experience Web censorship.

Read the full installation instructions for optional configuration steps that can help Encore better integrate with your site.

What sites does Encore measure?

Encore currently instructs its clients to measure a list of sites compiled by Herdict, which Herdict and its partners feel are important to measure. Herdict already asks its users to measure these same sites manually using its Web site and browser extension; Encore simply automates these measurements.

Can my site's visitors opt-out of Encore?

Yes, you can direct your users to the Encore settings page.

Is Encore ethical?

Except in egregious cases (e.g., child pornography), we are unaware of any instances where a user would get into trouble simply for attempting to access blocked content, especially because users typically have no knowledge of which sites are blocked. Encore does not measure pornographic sites and further mitigates user risk because requests are initiated by the user's browser as cross-origin requests, not as explicit user "clicks", similar to how a browser loads other third-party content and tracking software.

For abundance of caution, Encore currently only conducts a conservative set of measurements meant to demonstrate its technical merit. We are investigating how to tailor the set of sites that Encore measures to both yield interesting results and minimize risk to users. This includes discussions with experts in Internet policy. Our Institutional Review Board (IRB) has declined to formally review Encore because it isn't considered human subjects research.

Please contact us with your questions and concerns about Encore's ethics. We are eager to hear your experiences and feedback.

Do I need to inform my site's visitors about Encore?

Although we cannot provide legal advice, we believe that you are not required to inform your site's visitors about Encore or obtain their consent before collecting measurements. That said, Encore's installation instructions explain how your can inform your visitors of Encore's presence and allow them to disable Encore entirely.

Countless sites already load resources from numerous third parties and record detailed measurements about users' browsing behavior without informing them or obtaining their consent. (For example, this paper studies the pervasiveness of third-party Web tracking.) Rather than loading third party resources for commerical purposes (e.g., to track users or build consumer advertising profiles), Encore uses the same mechanisms "for good" to measure Internet censorship.

Ultimately, you and your institution should evaluate the legality and ethics of Encore for yourselves, particularly if you are outside the United States.

How can I learn more about Encore?

Our paper in SIGCOMM 2015 explains Encore's design, implementation, and evaluation in great detail.

Is Encore open source?

Yes, Encore's source is available under the MIT license from the Encore git repository.

Who are you?

We are Sam Burnett and Nick Feamster, researchers at Georgia Tech and Princeton University.

Please email us if you have questions or comments about Encore.