Signal has begun using a practice called domain fronting to counter the Egyptian government’s censorship of their service. Instead of using Open Whisper servers and domains to send content, they are using the Google App Engine. This effectively hides traffic under an encrypted and trusted domain, masking it among the noise of Google traffic. What looks similar to Google searches, calendar requests, and document collaboration could now hold encrypted messages.
Domain fronting works… too well.
@Google there’s a problem in using your search page and gmail through ur chrome app on both iPhone and laptop. In Egypt! What’s wrong?
— Youssra Selim (@YoussraSelim) January 5, 2017
In order to combat this, Egypt would have to blacklist all Google traffic, which they did… for a little bit. A blog called Egyptian Chronicles reported that both Signal and Google have been intermittently going up and down over the last week or so.