Signal must have very good encryption. The app has now moved higher in my opinion of its security and privacy since Egypt has blocked the use of Signal within the country. The Egyptian government apparently has not been able to break the encryption used in Signal.
Mada Masr, an Egypt-based media organization, reported yesterday that several users took to Twitter over the weekend to report that they could no longer send or receive messages while on Egyptian IP addresses. Open Whisper Systems, the team behind the app, told a user asking about a situation that everything was working just as intended on their end. Now that the company has confirmed that the country is blocking access to Edward Snowden’s preferred messaging app, it has begun working on a way to circumvent the ban. They intend to deploy their solution over the next few weeks.
Details may be found in the Engadget web site at https://www.engadget.com/2016/12/20/egypt-blocks-signal/.