Signal is already available for iOS, but the Android app was divided into two parts: TextSecure and RedPhone. Open Whisper Systems wants with Signal to put all secure communications in one app. Signal is completely open source, is maintained by many security experts and even has the approval of whistleblower Edward Snowden.
This is what you can do with the Signal app
Signal uses end-to-end encryption, ensuring that messages can be decrypted only by you and your partner. TextSecure servers have no access to your chats or metadata such as the title and composition of a group. Signal uses your phone number and requires no additional logins, usernames, passwords or PINs. It works much the same as WhatsApp: your phone number is how you can be reached.
In addition, it is possible to make secure calls with Signal. This works through VoIP; calls over the Internet. When the call is set up an encrypted connection, which is secured by end-to-end encryption. During our testing, calling with Signal worked good, but especially if using a 4G or WiFi connection.
Open Whisper Systems earns money through donations and investments from privacy advocates. This allows a small team of developers on a freelance basis to work on the app, and there are many enthusiastic developers who help improve the code of the app and quickly fix potential vulnerabilities.
Download Signal for Android and iPhone
Signal for Android is available for free in the App Store and Google’s Play Store.