Special Edition is the blog for security testing business SE Labs. It explains how we test security products, reports on the internet threats we find and provides security tips for businesses, other organisations and home users.
Monday, 21 August 2017
The Government Encryption Enigma
Is Amber Rudd right about encryption? Jon Thompson isn't so sure.
UK Home Secretary Amber Rudd recently claimed in an article that "real people" prefer ease of use to unbreakable security when online. She was met immediately by outrage from industry pundits, but does she have a point?
Though paywalled, as reported elsewhere, Rudd asks in her article, "Who uses WhatsApp because it is end-to-end encrypted, rather than because it is an incredibly user-friendly and cheap way of staying in touch with friends and family?"
Rudd name-checked Khalid Masood, who used WhatsApp minutes before he drove a van into pedestrians on Westminster Bridge killing three, and then fatally stabbed a police officer outside Parliament before being shot dead. However, Masood was not part of any MI5 investigation. In fact, a week after the attack, police had to appeal for information about him. His final WhatsApp message seems to have been the first sign that he was about to strike. The recipient was entirely innocent, and knew nothing of his murderous intentions.
There are plenty of other atrocities that were planned in part via social media apps. The attacks on Paris in December 2015, and the Stockholm lorry attack to name but two. In the UK the new UK Investigatory Powers Act 2016 (IPA), which caused so much fuss last year, can compel vendors to decrypt. So, why not just use that? The answer is somewhat complicated.
The IPA makes provision for Communications Service Providers to be served with a notice that they must remove encryption from messages to assist in the execution of an interception warrant. Apart from Providers needing access to private decryption keys, reports suggest that any move to enforce this measure would meet stiff opposition, and may not even be enforceable.
Many of the most popular secure messaging apps use the Signal Protocol, developed by Open Whisper Systems. This is a non-profit organisation and lies outside the UK's jurisdiction, so its compliance would be difficult to obtain, even if the companies using the protocol agreed to re-engineer their platforms to include backdoors, or to lower encryption standards. There are also plenty of other issues to be resolved if Rudd is to get her way.
If the government mandates weaker encryption for messaging apps in the UK, then companies will face difficult business choices and technological challenges. It boils down to a choice: they could weaken their encryption globally, or they could just weaken encryption in the UK. But what happens
if you send a secure message from outside the UK to someone inside the country? Can the UK authorities read it? Can the recipient, using a lower encryption standard, decrypt it? How would international business communications work if the UK office doesn't use the same encryption standard as a foreign parent company?
This isn’t the first time the UK government has attempted to find an answer to the problem of encryption. Back in January 2015, the then-Prime Minister David Cameron gave a speech in which he said there should be no means of communication "which we cannot read". He was roundly criticised as "technologically illiterate" by opposition parties, and later clarified his views, saying he didn’t want to ban encryption, just have the ability to read anyone's encrypted communications.
Authoritative voices have since waded into the argument. Lord Evans, the former head of MI5, has recently spoken out about the problems posed by strong encryption: “It’s very important that we should be seen and be a country in which people can operate securely – that’s important for our commercial interests as well as our security interests, so encryption in that context is very positive.”
Besides, if the government can decrypt all messages in the UK, won’t genuine terrorists simply set up their own "dark" services? Ten seconds on Google Search shows plenty of open source, secure chat packages they could use. If such groups are as technologically advanced as we're led to believe, then it should be simple for them, and terrifying for the rest of us. Wouldn’t it be better to keep such groups using mainstream apps and quietly develop better tools for tracking them via their metadata?
Rudd's argument that "real people" want ease of use over strong encryption implies that secure apps are in some way difficult to set up and require effort to maintain. The opposite is plainly true, as anyone who's ever 'butt dialled' with their mobile phone can tell you.
Rudd's argument also plays into the idea that if you have nothing to hide you have nothing to fear. While writing this piece, I accessed several dozen online information sources, from mainstream news reports of terrorist outrages to super paranoid guides for setting up secure chat services. I accessed many of these sources multiple times. I didn’t access any extremist material, but my browsing history shows a clear and persistent interest in recent atrocities perpetrated on UK soil, secure chat methods, MI5 and GCHQ surveillance methods, encryption algorithms, and so on. Joining the dots to arrive at the wrong conclusion would be a grave mistake, and yet without the wider context of this blog piece to explain myself, how would authorities know I'm not planning to be the next Khalid Masood or Darren Osborne? The answer lies in developing better tools that gather more context than just what apps you use.