Jonathan Evans says although encryption services have hampered terrorism fight he does not support curtailment of its use

A former head of MI5 has spoken out against curtailing use of encryption in messaging apps despite warning that Islamist terrorism will remain a threat for up to another 30 years.

Jonathan Evans said the terrorist threat to Britain was a “generational problem”, and suggested the Westminster Bridge attack in March may have had an energising effect on extremists.



Q&A What are the pros and cons of encryption? Show Hide Without encryption, everything sent over the internet – from credit card details to raunchy sexts – is readable by anyone who sits between you and the information's recipient. That includes your internet service provider, and all the other technical organisations between the two devices, but it also includes anyone else who has managed to insert themselves into the chain, from another person on the same insecure wireless network to a state surveillance agency in any country the data flows through.



With encryption, that data is scrambled in such a way that it can only be read by someone with the right key. While some older and clumsier methods of encryption have been broken, modern standards are generally considered unbreakable even by an attacker possessing a vast amount of computer power.



But while encryption can protect data that it is vital to keep secret (which is why the same technology that keeps the internet encrypted is used by militaries worldwide), it also frustrates efforts by law enforcement to eavesdrop on terrorists, criminals and spies.



That's particularly true for “end-to-end” encryption, where the two devices communicating are not a user and a company (who may be compelled to turn over the information once it has been decrypted), but two individual users.

But Lord Evans, who retired from the security service in 2013, told BBC Radio 4’s Today programme that he would not support a clampdown on use of encryption.



His comments came after Amber Rudd, the home secretary, argued that internet companies were not doing enough to tackle extremism online. She has previously singled out the use of encryption as a problem.

Acknowledging that use of encryption had hampered security agencies’ efforts to access the content of communications between extremists, Evans added: “I’m not personally one of those who thinks we should weaken encryption because I think there is a parallel issue, which is cybersecurity more broadly.

“While understandably there is a very acute concern about counter-terrorism, it is not the only threat that we face. The way in which cyberspace is being used by criminals and by governments is a potential threat to the UK’s interests more widely.

“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.”

After the home secretary’s intervention at the Global Internet Forum to Counter Terrorism in California this month, the companies taking part said they were cooperating to “substantially disrupt terrorists’ ability to use the internet in furthering their causes, while also respecting human rights”.

Looking ahead, Evans warned of the threat of a cyber-attack against the internet of things – the networking of physical devices, ranging from cars to lightbulbs to TVs – as a major issue.



“As our vehicles, air transport, our critical infrastructure is resting critically on the internet, we need to be really confident that we have secured that because our economic and daily lives are going to be dependent on the security we can put in to protect us from cyber-attack,” he said.

But the threat of Islamist terrorism was likely to remain at the fore for 20-30 years, he warned.

“We’re at least 20 years into this. My guess is that we will still be dealing with the long tail in another 20 years’ time – I think this is genuinely a generational problem,” Evans said.

“I think that we are going to be facing 20 or 30 years of terrorist threats and therefore we need absolutely critically to persevere.”

He said the London bombings in July 2005 triggered an “energising effect on the extremist networks in the UK”, and thought there would be a similar feeling after the Westminster Bridge attack.



“We did see a huge upsurge in threat intelligence after 7 July and I suspect that there’s the same sort of feeling in the period after the Westminster Bridge attack – that a lot of people who thought ‘I’d like to do this’ suddenly decided ‘Yep, if they can do it, then I can do it’.”

Since the atrocity in March, there have been attacks in Manchester, London Bridge and Finsbury Park.

Evans, now an independent crossbencher in the House of Lords, also told the programme he would be surprised if Russia had not attempted to interfere with British democracy, after repeated allegations of Kremlin interference in foreign elections.



He said: “It would be extremely surprising if the Russians were interested in interfering in America and in France and in various other European countries but were not interested in interfering with the UK, because traditionally I think we have been seen as quite hawkish and therefore I would be surprised if there had not been attempts to interfere with the election.”