A few weeks before a major change to the way in which UK viewers access online pornography, neither the government nor the appointed regulator has been able to provide details to the BBC about how it will work.
From April 2018, people accessing porn sites will have to prove they are aged 18 or over.
The regulation is designed to protect children from explicit content.
Both bodies said more information would be available soon.
The British Board of Film Classification (BBFC) was named by parliament as the regulator in December 2017.
The rule is part of the Digital Economy Act, overseen by the Department for Digital, Culture, Media and Sport.
The porn industry has been left to develop its own age verification tools.
Prof Alan Woodward, cybersecurity expert at Surrey University, told the BBC this presented porn sites with a dilemma – needing to comply with the regulation but not wanting to make it difficult for their customers to access content.
"I suspect what the industry is trying to produce is an age verification system that is pseudo anonymous as opposed to the current totally anonymous sites that currently exist," he said.
"I can't imagine many porn-site visitors will be happy uploading copies of passports and driving licences to such a site. And, the site operators know that."
He also questioned how any verification tool would get around the use of virtual private networks (VPNs) which mask the geography of a device – the rule will only apply in the UK.
"I understand why the government is doing this but the devil is in the detail and it doesn't appear to have been thought through," he said.
"I can see how the government's move will perhaps prevent casual viewing by underage visitors but I'm not sure it will prevent any 'tech-savvy' underage viewer."
One verification tool, called AgeID, has been built by Mindgeek, which styles itself as an IT firm and also runs porn sites PornHub, YouPorn and RedTube.
The firm said in a statement about AgeID that data protection and privacy principles were "at its core".
It also told Sky News that it would not store personal data related to the age verification process.
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