Writing that "privacy has never been an absolute right," Robert Hannigan, the head of British spy agency GCHG, urged the US tech sector to assist the fight against terrorism and other crimes by opening up their proprietary networks to government authorities. Hannigan, in a Financial Times editorial on Monday, suggested that "technology companies are in denial" over the Internet's use "to facilitate murder or child abuse." He wrote that the time was ripe for "addressing some uncomfortable truths" and went on to say the public wouldn't mind if technology companies gave governments backdoor access either.

They do not want the media platforms they use with their friends and families to facilitate murder or child abuse. They know the Internet grew out of the values of western democracy, not vice versa. I think those customers would be comfortable with a better, more sustainable relationship between the agencies and the technology companies.

"Better do it now than in the aftermath of greater violence," Hannigan added.

Hannigan's opinion piece follows similar comments by FBI Director James Comey and US Attorney General Eric Holder. And a day after Hannigan's comments, the Electronic Frontier Foundation of San Francisco released a "Secure Messaging Scorecard" that rated which messaging technologies are "truly safe and secure."

Holder, for example, blasted Apple and Google last month for building encryption by default into their latest mobile operating systems—meaning that authorities could not physically unlock a phone to scour its contents even with a valid court order. Holder urged the tech sector "to work with us to ensure that law enforcement retains the ability, with court-authorization, to lawfully obtain information in the course of an investigation, such as catching kidnappers and sexual predators."

Comey, for his part, said he was troubled about the marketing of smart phones that can't be physically searched by law enforcement.

"What concerns me about this is companies marketing something expressly to allow people to place themselves beyond the law," Comey said. He said the bureau has reached out to Apple and Google "to understand what they're thinking and why they think it makes sense."

At its core, the latest crypto wars follow the leak of classified documents by former National Security Agency contractor Edward Snowden. After that event, the public has become increasingly wary of overreaching surveillance by government agencies. Anti-spy technology has become much more popular, gaining huge support on Kickstarter for example.

That was not lost on Hannigan.

"Terrorists have always found ways of hiding their operations," he wrote. "But today mobile technology and smartphones have increased the options available exponentially. Techniques for encrypting messages or making them anonymous which were once the preserve of the most sophisticated criminals or nation states now come as standard. These are supplemented by freely available programs and apps adding extra layers of security, many of them proudly advertising that they are 'Snowden approved.' There is no doubt that young foreign fighters have learnt and benefited from the leaks of the past two years."

Hannigan added: