Open Whisper Systems, which offers encrypted communications, has equipped its iOS app with the ability to send encrypted messages. Until now, Signal could only be used to make encrypted VoIP calls.
The Open Whisper Systems project already had an Android app that let users send encrypted messages: TextSecure. However, iOS users could only use the app to make encrypted calls. However, Signal has now gained support for encrypted chats, the non-commercial project has revealed.
Signal is fully compatible with TextSecure: users of the iOS app can therefore exchange messages with users of TextSecure, which is only available on Android. In addition, Signal still offers the ability to set up encrypted VoIP calls, with the app being compatible with RedPhone, Open Whisper Systems’ encrypted VoIP client for Android.
Use of the apps, whose source code is public, is free; the Open Whisper Systems team consists of volunteers. According to security researcher Moxie Marlinspike, who is collaborating on the project, costs so far have been covered by donations, although he does not rule out the possibility that the project may require a small contribution from users in the future.
TextSecure, Signal and RedPhone offer end-to-end encryption, which means that the encryption is set up directly between the interlocutors. Messages are encrypted by the sender and only decrypted again by the receiver; messages are therefore not transparent to the organization behind the project, nor to attackers and governments. Previously, Open Whisper Systems built in end-to-end encryption for Android users in conjunction with WhatsApp.
There are few apps that offer cross-platform encrypted chats. One of the services is the paid app Threema. Telegram also has the option to set up encrypted chats, although not everyone is charmed by the cryptography developed by Telegram itself.