Signal Secure Messenger Review & Test Drive: Free And Open Source Alternative To WhatsApp/Telegram/Facebook Messenger


This article is a new episode of the Free Messenger Heroic Saga (Tox, Matrix, Tor Messenger). I highly recommend to read it for comparison. Privacy – very important thing for everyone today and tomorrow it may be a myth in the world of mega corporations, user tracking, automatic email parsing, security agencies with full access to everything and everyone.

Signal Secure Messenger – free and open source messenger for general platform: Linux/Windows/OSX as Google Chrome or Chromium extension and Android/iOS created by Whisper Systems. All desktops and mobile clients are open source and licensed with GNU GENERAL PUBLIC LICENSE v3; source code is available on Github.

Technical details

General features:

  • end-to-end encryption: no one can read messages, only users of private conversation/chat
  • private keys are saved only in each device, not in cloud
  • authentication via SMS or mobile call, no registration/personal information
  • multimedia: audio call, SMS and MMS analog via internet with pictures and video, chat groups
  • screenshot preventing: Signal does not allow other programs to make a screenshot of the conversation
  • free as free beer – use Signal without paying and without advertisements
  • it can replace the standard program for SMS/MMS and calls

Android version of Signal needs Google Apps, proprietary pack of application. This fork and repository for Fdroid can afford to use Signal without Google Apps. Cryptography from Whisper Systems has a good rating from the experts:

Bruce Schneier, internationally renowned security technologist:

I am regularly impressed with the thought and care put into both the security and the usability of this app. It’s my first choice for an encrypted conversation.

Matt Green, Cryptographer, Johns Hopkins University:

After reading the code, I literally discovered a line of drool running down my face. It’s really nice.

Edward Snowden:

Use anything by Open Whisper Systems

Signal’s cryptography uses AES-256, HMAC-SHA256 and Curve25519. Signal also don’t support  OTR cause it’s unreal in asynchronous messaging. More information about the Signal protocol you can find here. Whisper Systems do not have access to any messages, multimedia content, call logs or private keys.

Note about firewall: TCP port 31337 and all UDP ports (Signal use random UDP port everytime) need to be open.

And remember about login: no usernames – only mobile number, SIP or Google Voice number.

You can also host your own Signal server, more information about it here.


The graphic interfaces of Signal are very easy and intuitive. After first run you need to authenticate via mobile phone or SIP:

Desktop version currently in beta stage:

Settings window:

Privacy settings – you can look application with passphrase, block contacts and prevent a screenshot from other applications

Pairing device via QR-code in desktop version:


The Signal is very interested secure, open source, and free messenger with good reputation. He now has a small popularity, but it’s difficult without the big advertisement companies, good financial support and hundred of developers. Please use and share it, donates also can help – this program needs more attention. Thanks for reading, stay secure and use the open source software.


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