New encryption technologies are reducing the ability of Five Eyes' countries to make sense of some of data they intercept.

A fresh push by "Five Eyes" countries to ensure authorities can intercept and read secret online communications will be a threat to Kiwis' online privacy and security, New Zealand's non-profit internet society InternetNZ fears.

The governments of the United States, Britain, Canada, Australia and New Zealand expressed concern about the use of powerful "end-to-end" encryption technology by "child sex offenders, terrorists and organised crime groups" in a communique issued last week.

They indicated it was becoming harder for law enforcement agencies to make sense of data they intercepted.

They agreed that if they continued to encounter "impediments to lawful access to information", they might pursue "technological, enforcement, legislative or other measures to achieve lawful access solutions".

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InternetNZ said encryption had practical benefits in protecting people's data from hackers and was also "an important part of stopping the internet being used as a surveillance tool".

It said in a statement that it was worried the Government might "sacrifice the online security of all New Zealanders".

"One recommendation the Five Eyes put forward could possibly break end-to-end encryption – and this is really worrying for New Zealanders," chief executive Jordan Carter said.

"We need encryption for things like online banking and booking travel safely. We need it to keep ourselves safe and secure online. Without it no one will have trust in the internet."

End-to-end encryption – which is used by some popular messaging apps such as WhatsApp – involves encrypting data as soon at it is created on a device and until it is read by the recipient.

That means communications may not be able to be easily deciphered even with the assistance of the technology companies that carry them.

About 18 per cent of all internet traffic was secured by end-to-end encryption and that was expected to grow to 22 per cent next year, InternetNZ estimated.

Carter said intercepting communications was not the only way, or a sure way, of foiling the likes of terrorist plots and "the fundamental point is what is the trade-off that we are being asked to make?".

CRAIG SIMCOX/STUFF InternetNZ chief executive Jordan Carter says there is a "false dilemma" but if trade-offs need to be considered, there should be broad debate.

Any decisions on encryption should be made following a broad public debate and not made by organisations whose sole interests were crime-fighting and which might view any trade-offs through their own particular lens, he said.

"This is the other problem with the Five Eyes environment – they are not having a considered debate with economic policy makes and technology firms in the room and that is a major problem."

The Five Eyes communique said each of the five countries would consider how best to implement the principles they had set out.

"Any response, be it legislative or otherwise, will adhere to requirements for proper authorisation and oversight, and to the traditional requirements that access to information is underpinned by warrant or other legal process," they said.

"We recognise that, in giving effect to these principles, governments may have need to engage with a range of stakeholders, consistent with their domestic environment and legal frameworks," the communique also said.