Threema adds end-to-end encrypted calling to messenger

The secure messenger app Threema now has the ability to make encrypted voice calls. The feature was added to the application last week after a beta testing phase. The app can make a ‘phone call’ without also sharing the user’s phone number.

Threema has received the update with both the iOS and Android versions. The Windows Mobile version of the app has not been given the feature and the Swiss developer is not saying anything about any development of this. Like the application’s text chats, the voice conversations are end-to-end encrypted. Threema’s encryption uses the open source encryption library NaCl, which was developed by Daniel Bernstein.

Threema goes the extra mile in addition to e2e encryption. Thanks to the use of a constant bit rate in the audio encoding, the format of the data packets that are exchanged must not be inferred by a ‘listening’ party. Threema is not free: the developers ask 2.99 euros for the app.