The secure smartphone that won’t get you beaten with rubber hoses

Interest in secure communications is at an all time high, with many concerned about spying by both governments and corporations. This concern has stimulated developments such as the Blackphone, a custom-designed handset running a forked version of Android that’s built with security in mind.

But the Blackphone has a problem. The mere fact of holding one in your hand advertises to the world that you’re using a Blackphone. That might not be a big problem for people who can safely be assumed to have access to sensitive information—politicians, security contractors, say—but if you’re a journalist investigating your own corrupt government or a dissident fearful of arrest, the Blackphone is a really bad idea. Using such a phone is advertising that you have sensitive material that you’re trying to keep secret and is an invitation to break out the rubber hoses.

That’s what led a team of security researchers to develop DarkMatter, unveiled today at the Hack In The Box security conference in Kuala Lumpur. DarkMatter is a secure Android fork, but unlike Blackphone and its custom hardware, DarkMatter is a secure Android that runs on regular Android phones (including the Galaxy S4 and Nexus 5) and which, at first glance, looks just like it’s stock Android. The special sauce of DarkMatter is secure encrypted storage that selected apps can transparently access. If the firmware believes it’s under attack, the secure storage will be silently dismounted, and the phone will appear, to all intents and purposes, to be a regular non-secure device.

The full details of DarkMatter still aren’t nailed down, and it won’t reach the market until some time next year.

A secure phone is only one of the things that a person needs for secure communications. While there are ways of securing e-mail and instant messaging communications, we’ve written before about the awkwardness that these systems generally impose on their users. They’re annoying to use, especially for things like setting up first contact with someone.

Recognizing the importance of secure messaging to a secure phone, the developer behind DarkMatter, pseudonymous Thailand-based South African security researcher known as the grugq, is releasing a new mobile messaging client that addresses this problem.

The messaging client is built on the foundation provided by Adam Langley’s Pond messaging system. Unlike systems like PGP e-mail or Off-The-Record instant messaging, Pond is designed from the ground up to be a secure messaging protocol. Pond has a few particular features that make it compelling. First, it’s secure by default. It has no non-secure version to fall back to if someone makes a mistake, for example. Message transport is provided over the tor network, effectively masking sender and recipient identities and locations. The messages themselves are fixed length, at just under 16 kilobytes, to prevent detection of traffic patterns.

Second, Pond has a neat solution to the “first contact” problem. Unlike e-mail, Pond communication can only occur between two people who’ve already agreed to communicate; there’s no way of sending unsolicited spam. That two-way communication is established in the first place by mutual agreement of a passphrase, which can be communicated through IM, voice chat, in person, or however else two parties want to share it. Both parties post a (time-limited) message derived from the passphrase to a server and use this to share keys with each other. Once this key sharing has taken place, the passphrase isn’t used, and even if an attacker discovers it, it’s no longer useful.

Third, it’s anonymous. PGP, for example, is tied up with questions of identity. Pond deliberately has no kind of identity system, with the communication between two parties being entirely anonymous.

Pond has impressed crypto experts. Well-known cryptography professor Matthew Green at Johns Hopkins University says that it is “probably the most sophisticated anonymous, secure messaging client out there.” As a fairly new piece of software, it could do with further scrutiny, but Green is “more confident in it than in quite a few common privacy tools.”

The grugq and others have created an Android version of the Pond client software, making this secure messaging system easy to use, and available on the devices that people tend to carry with them everywhere. The software isn’t quite finished yet, but will be available soon through Google Play.

It’s designed to be very simple and easy to use, to ensure that even those who are not particularly technically adept can use it—a recurring theme in secure communications software is that it’s impenetrably complex to non-experts. The workflow is straightforward and similar to that of Gmail or the Telegram messaging client. With Pond’s simple initial key exchange, and no risk of ever accidentally using the software insecurely, it should be a boon for journalists, dissidents, and freedom fighters around the world who need secure comms.