GCHQ has criticised reports that the UK government is turning the nation into a police state, arguing that the agency does not have the resources for umbrella surveillance.
Ciaran Martin, GCHQ's director general for cyber security, called for businesses to begin working with the agency, arguing that many concerns about its surveillance activities are exaggerated.
"Our intelligence gathering has been the source of controversy recently. I can't comment on that. The Queen's Speech laid out the plans," he said during a keynote speech at InfoSec Europe.
"But I would note that we use our powers extremely carefully. One of the things that's been said flippantly in our defence is that we don't have the power to do a mass intrusion."
Martin claimed that this is true. "We're simply not big enough to put a big cyber umbrella over the entire country. Our focus has to be on the high-end attacks: risks to national infrastructure, securing defence assets and assisting government departments making the transition to digital services."
Martin's comments follow concerns about the UK government's plans to revisit the controversial Snoopers' Charter and introduce legislation that would hamper companies' abilities to encrypt customer data in a way that the GCHQ could not access.
The concerns led to a backlash against the government and GCHQ in the security industry.
Pretty Good Privacy encryption creator and Silent Circle chief Phil Zimmermann described the UK's plans as Orwellian, while revealing his intention to move his company from the US to Switzerland for the same reason.
When asked about these concerns, Martin said that the ultimate decision regarding GCHQ's powers will be made by the government after a "lengthy and thorough period of debate and examination".
Martin added that the UK government has plans to improve the nation's digital economy, and would not let GCHQ mount any operations undermining this effort.
"The tech boom is a huge economic and social opportunity. This is something the government attaches great importance to," he said. "It is not our aim to slow or shut down the march of tech and, even if it was, we wouldn't be allowed to."
Looking to the future, Martin said that the public and private sectors will have to work together to achieve the government's growth plans, claiming that the cyber threats facing industry are too big for any firm to take on alone.
"We see real threats to the UK on a daily basis and the scale and rate are showing no signs of abating," he said.
"We think about motivation, why the bad people do what they do. Looking at this there are three words that explain the motivation in my mind: money, power and propaganda."
Martin highlighted the 2014 attack on Sony as proof of his claim, arguing that businesses are now the targets of criminals, state-sponsored groups and rogue hacktivists.
"Any organisation with money on a system is a target for cyber attacks. [Additionally] for some states operating outside national norms, getting one over on a rival who is more developed is attractive," he said.
"In an age when the reputation of organisations counts for so much, never discount this as motive. The Sony attack was destructive, but the goal was making a loud media splash. The same is true of hacktivists."
He added that the need for collaboration is pressing as many companies are still failing to follow basic cyber security best practice.
Martin has urged firms to take advantage of existing government guidance, such as GCHQ's 10 Steps to Cyber Security, the Cyber Essentials scheme and CERT-UK's Common Cyber Attacks: Reducing the Impact, and adopt more dynamic security strategies.
"Following the basic approach - boundary firewalls, malware protections, whitelisting, user access control - you can dissuade the casual hacker. Making it a bit more trouble can be a big deterrent," he said.
"[However] a determined attack will always have a decent chance of getting in. What is important is finding what matters most and giving that the most robust security.
"If you are attacked, know how to clean up. Know how to keep the business going. This again comes down to knowing what matters most: keeping resources going in worst case scenarios."
Martin cited GCHQ's efforts in combatting distributed denial of service (DDoS) attacks on its public website as an example.
"Our public site, which is a series of static pages, has been the subject of DDoS attacks. We defend this as best we can as it's bad if they're successful," he said.
"But our public website is not a priority essential mission security area, so if it goes down we don't stop. We have better areas to place resources. We've figured out what's essential."
GCHQ is one of many government departments calling for increased collaboration between the public and private sectors in combating cyber threats.
US secretary of defence Ash Carter urged businesses to work with government departments when combating cyber threats during a speech at Stanford University in April.
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