Best secure mobile messaging apps - Pryvate

Launched in November 2015, Cryptique’s Pryvate is intended for use by businesses as competition for high-end mobile security such as the Blackphone/Silent Circle which embeds software inside a secured version of Android. As with that service, Pryvate is another do-it-all voice, video, messaging, IM, secure file transfer, and secure storage app (integrating with Dropbox, One drive, BOX) and will integrate with third-party email clients for added convenience.

On the subject of Silent Circle, the underlying voice and IM protocol used by Pryvate is Phil Zimmermann’s ZRTP perfect forward secrecy encryption. Other features is IP shielding whereby uses can bypass VoIP and IM blocking without giving away their real IP address – the app tunnels across the Internet using Pryvate’s own UK Jersey-based servers.

The mobile service costs £4.68 (about $7) per month as a subscription but can be used after the one-month trial in the form of PryvateLite, which allows full secure IM and picture sharing with unlimited phone calls up to a duration of 1 minute. We’re not sure how practical that would be to use but it’s an option. A version including desktop capability is available for $9.99 (about $14) per month.

We weren’t able to organise a subscription in time for this article but will test this app more thoroughly in future and update this feature.

Security: 4096-bit encryption, with AES 256-bit key management. Complex mini PKI design with perfect forward secrecy design.

Pro: mature underlying technology, messaging, IM, video, voice and storage integration

Con: free service a bit limited despite reasonable month subscription

Others to consider:

SaltDNA Enterprise – launched in November 2015, this promises centralised IT control which will appeal to organisations that prefer to manage security for themselves.

Blackphone - the most mature if expensive platform by some distance, complete with tight integration in the dedicated £658 Android-based smartphone that gives the company its name. The software behind the Blackphone is from Silent Circle, a company founded in 2012 to exploit technology developed by Phil Zimmermann, the iconic figure who in the early 1990s invented the famous PGP secure messaging program that pioneered encrypted communications. Zimmermann was - and still is - the real Snowden.