“We have a bit of a problem with the press saying that the Blackphone will make you NSA-proof,” Phil Zimmerman, one of the Blackphone’s creators, tells me at Mobile World Congress in Barcelona. “If someone [at the Blackphone booth] tells you that it’ll protect you from the NSA, I’ll fire them.”
As we’ve previously said, the Blackphone is essentially a mid-to-high-end Android smartphone (a customised build called PrivatOS) that comes with a bunch of privacy and security-oriented apps. As far as cryptography goes, the Blackphone’s implementation of Silent Circle’s secure communication apps is pretty darn good. The Blackphone also offers an encrypted file system. The per-app granular permissions system is neat (but buggy in its current implementation, as many apps revolt when they find out that they’ve had their permissions revoked without being informed of the fact).
There’s no Google Play store pre-installed, but a guy at the booth told me you could install it (though I don’t know how Google would feel about that). Priced at $630 (£375) over in the US, it’s a pretty good deal, if you want a readymade device that is more secure out of the box than the latest iPhone or Galaxy S5.
What the Blackphone isn’t, however, is a completely secure communications device. Phil Zimmerman, creator of PGP, co-founder of Silent Circle, and one of the Blackphone’s creators, knows this. The guys at Geeksphone (the hardware makers of the Blackphone) know this. I know this. You know this. Most of the press and the majority of the general public, however, appear to think otherwise.
Now, to be fair, Blackphone’s creepy, scare-mongering website was partially to blame for this (the site has now been significantly updated) – but it’s also down to the fact that most people just don’t understand how cryptography and mobile telephony works. We have been conditioned to think that good cryptography is some kind of universal security panacea – but the complete story is much more complex than that.
Basically, the Blackphone provides a good level of encryption between you and the target of your communication (VoIP). It does not provide any protection over the standard GSM/WCDMA radio. It also doesn’t provide any hardware-level security, except for the encrypted file system. Assuming the encryption doesn’t have some kind of backdoor, and that Zimmerman’s clever crypto scheme isn’t flawed, the Blackphone probably stops the NSA (and other intelligence agencies) from scanning the contents of your data packets. If you really believe that the NSA is interested in the minutiae of your everyday life, then by all means use the Blackphone.
The problem is, the Blackphone only protects your communications at the highest level – in software, running at a very high level on your Android-based smartphone. The Blackphone does not protect you against vulnerabilities in the Android subsystem, in the application processor (SoC), or in the baseband itself. Your phone’s baseband – the device that handles negotiation with cell towers and other messy stuff – is essentially a black box, with its own CPU and operating system. The baseband has complete, low-level access to your microphone – access that the Blackphone cannot mitigate against. If the NSA really wants to tap your phone, that is probably the attack vector that it would use.
He adds: “If the NSA wants to hack you, they’ll use a zero-day vulnerability,” which, as he points out, by definition, is basically impossible for the Blackphone (or indeed any device) to protect you from. Zimmerman says that during the development process, the first question he asked was whether the baseband could be secured. The answer is not yet – but if the Blackphone is a commercial success, it gets us one step closer. “The Blackphone is just the beginning of the conversation.”
To make a truly secure phone, we’d need to build a device that is completely open from the ground up. There are some ongoing efforts in open source basebands, and the emergence of software defined networking could help as well. This ignores the question of whether carriers would even let such a device onto their networks, though. The concept of a truly secure mobile communications device is certainly something we should continue to discuss, but we should be under no illusions that such a device will ever come to market.