Director general of the Australian Security Intelligence Organisation Mike Burgess told a hearing on Thursday that the laws hadn't created systemic weaknesses in networks.

Independent National Security Legislation Monitor James Renwick is reviewing the use of laws that allow law enforcement bodies to compel telecommunications and tech companies to allow access to encrypted communications.

Mr Burgess said more than 95 per cent of ASIO's most dangerous counter-terrorism targets use encrypted communications and that almost all electronic communications that have investigative value are encrypted.

Using the laws within 10 days of receiving assent was "a clear indication of its significance to our organisation," he said.

Opponents of the laws have argued that they would impede on the privacy of Australians, while also creating systemic weaknesses or back doors in communication platforms that could be exploited.

Mr Burgess said so far telecommunication providers had designed capabilities to view encrypted communications in collaboration with the intelligence agency.

"This assistance has not involved the development of any back doors to encryption or systemic weaknesses to networks or devices," he said.

Mr Burgess said his agency had no intention of introducing any weakness that would put the private communications of Australians at risk.

Dr Renwick is reviewing the law that was passed at the end of 2018, at the same time as a similar review by the powerful parliamentary intelligence and security committee.

In his opening statement, Dr Renwick said there was no "bright line" between content and metadata.

"The so-called 'golden age' when such unencrypted content or to an extent metadata could easily be read and comprehended by police, integrity and intelligence agencies, acting with lawful authority, has gone, perhaps forever."

"Instead such agencies now speak of a virtual world, which has gone dark, gone spotty, or even gone different."

Dr Renwick said he was "wary" of a binary argument between encryption for privacy and law enforcement

"Nothing I have seen to date suggests there's been anything like the idea of quote "mass surveillance" unquote as a result [of the law]," Dr Renwick said.