Open Whisper Systems, creator of the encrypted chat app ‘Signal,’ launched a new update to its app to circumvent government censorship efforts. The update came just days after the company confirmed that the Egyptian government had censored access to the app.
“We’ve been investigating over the weekend, and have confirmed that Egypt is censoring access to Signal,” Open Whisper Systems tweeted on Monday. Minutes later, the company tweeted, “We’ll begin deploying censorship circumvention in Signal over the next several weeks.”
The newly launched update skirts censorship efforts across the United Arab Emirates and Egypt.
The anti-censorship feature uses “domain fronting.” Countries with tight control over internet service providers can block direct requests to services on its blacklist. Service providers can circumvent this by using encrypted connections to major internet services to hide traffic. In Signal’s case, the major internet service is Google’s App Engine.
Google’s App Engine gives developers the option to redirect traffic from Google.com to their website. Because Google uses TLS encryption, the ISP only sees that a user has connected to Google.com.
When users in censored areas send messages through the Signal app, it will look identical to a Google search. Essentially, Google is serving as a proxy for Signal. Using this method, governments would have to block Google in order to block Signal.
Blocking major services, or the entire Internet, is a possibility. In 2011, the Egyptian government shut down the Internet. Brazil blocked use of WhatsApp after a drug investigation went wrong. The blocks did not last long in either case.
A handful of countries, including Iran, China and North Korea, have permanently censored a large swathe of the web.
Other anti-censorship tools also use domain fronting to circumvent censorship, including Psiphon, Tor, and Lantern. In addition to Google, these tools also use CDNs, like Akamai, Cloudflare, and Amazon Cloudfront.