Crypto chat app Signal bypasses censorship in Egypt and Emirates

Crypto chat app Signal has made a previously announced change that will allow Android users in Egypt and the United Arab Emirates to bypass the app’s traffic blockade. The software uses domain fronting for this.

Open Whisper Systems, the organization behind Signal, writes that with this technique, censorship is only possible by switching off the internet completely. The method works by using a known domain in the dns request and in the designation of the tls server and sending an https request to it. For example, a request on the ‘outside’ seems to be sent to Google, Amazon or Akamai. If a country wants to block such requests, it must shut down all traffic to these services, Open Whisper Systems considers.

In addition, the http host header, which is hidden by the encryption of https, contains the domain that is actually communicated with. This is the address of the Signal servers. According to the organization, domain fronting has now been enabled for all users with a phone number in Egypt and the United Arab Emirates. In subsequent Signal releases, Open Whisper Systems plans to include tools with which the app itself detects and, if necessary, bypasses censorship. That way, Signal users can travel to other countries without having to use a VPN.

The iOS version with domain fronting is in beta and should get a stable version soon. Signing up for the beta channel of the iOS version is possible by sending an email to Open Whisper Systems. The Android release includes some other features such as adding text and stickers to images.

Open Whisper Systems announced the censorship bypass feature earlier this week after it was found to be blocking communications through Signal in Egypt. According to the organization, if governments cannot eavesdrop on communication, they will try to block it.