Android still tends to be the default platform for secure messaging apps, but iOS versions usually become available after a short delay. The issue of platform support is more important than it might first appear.
Even if you don’t personally use an iPhone, for example, the fact that your favoured contacts do will render any app that doesn’t support both platforms useless if the same app is needed at both ends.
Some apps integrate with third-party applications, for instance email clients. That can be important for businesses – can the app support the preferred communications software used by an organisation and will it work across desktop as well as mobile? Some can, some can’t.
It should be noted that Apple has significantly ramped up privacy and security in its devices of late. Controversially, American intelligence recently demanded that Apple undermine its own encryption as part of a terrorist shooting investigation. But Apple said that it couldn’t, even if it wanted to.
At the end of the day, if you want to guarantee true privacy, you should be using a messaging service which works on a secure mobile browser or at least a trustworthy VPN combined with private mode on your phone.
But for those who want at least a surface level of safety assurance, here are the most secure messaging services for mobile out there.
Whatsapp CEO and cofounder Jan Koum grew up in communist Ukraine – where open dissent was not tolerated by the government. Leaving the country at 16 for Mountain View, California, in 1992, it wasn’t until 2009 when he and Whatsapp cofounder Brian Acton created an app designed to cut the number of missed calls they were getting.
This eventually mutated into Whatsapp, and by 2014 it had over 400 million users. Today it’s one of the most popular messaging apps out there. In 2016, the company revealed that it had more than one billion users.
There were three principles integral to Koum, listed in this extensive profile from Wired. The first two could be traced back to his Soviet roots, the good and the bad: one that the app should promote privacy and protect freedom of speech. The second: no adverts. The third was that it should be a gimmick-free user-friendly experience.
That said, the fact that Facebook owns Whatsapp will not be reassuring to the privacy-conscious. Facebook is notoriously aggressive about collecting user data and Facebook has signposted its intention to target users with ads based on Whatsapp data.
Where Whatsapp tends to be unavoidable at the moment is the sheer number of people on it, similarly to Facebook Messenger. While there are more secure messaging apps on the market, its popularity does sell it – and at least it does tout a degree of privacy (even if it’s Facebook that owns the data).
Here’s the technical stuff.
Whatsapp started using the TextSecure platform (now called Signal – see below) from the Open Whisper Systems in 2015, which improves security by using true end-to-end encryption with perfect forward secrecy (PFS). This means the keys used to scramble communication can’t be captured through a server and no single key gives access to past messages.
In April 2016, the Signal protocol was rolled out as a mandatory upgrade to all WhatsApp users across all mobile platforms, an important moment for a technology that had spent years on the fringes. At a stroke it also made Open Whisper Systems the most widely used encryption platform on earth.