Android apps for encrypting calls and texts

US company Whisper Systems has released RedPhone and TextSecure, two free applications for Android smartphones that enable secure communication. RedPhone encrypts VoIP calls using the ZRTP open standard. In contrast to many other SIP programs, RedPhone does not use a SIP gateway for communication, but establishes a direct connection to the other (RedPhone) user via WLAN or UMTS. A switch operated by Whisper Systems, which sends a text to the receiving caller to initiate the connection, is required to set-up the connection.

TextSecure encrypts texts using the Off-the-Record-Messaging protocol and elliptic curve-based cryptography. In contrast to standard protocols, this means that it's not subsequently possible to determine who has used which key, therefore facilitating deniability. An FAQ describing how the two programs work is available on the company's web site.

The applications are currently available as compiled beta versions only, but the company is intending to publish the source code shortly. Calls can currently only be made to and from US numbers, but support for international numbers is also in the pipeline.

Whisper Systems is the brainchild of Moxie Marlinspike, whose main interest is developing software for cracking encrypted connections and who is well known for his talks at security conferences.

See also:

• SSL flaw revealed at Black Hat, a report from The H.

(crve)