Brits who want to watch adult material without handing over their credit card details may soon have to buy 'porn pass' codes from their local dairy.

But there's doubt such a system will do much to stop kids accessing material they shouldn't be.

Later this year, the UK government will require websites with age-restricted material to verify users' ages before letting them in.

"The Government is committed to keeping children safe from harmful pornographic content online and that is exactly what we are doing," Secretary of State for Culture, Media and Sport Karen Bradley said when the new rules were announced in late 2016.

"Only adults should be allowed to view such content. If sites refuse to comply, they should be blocked."

Fines for websites that don't abide by the rules face fines of up to £250,000 (NZ$486,000).

The system was due to go live in April, but has been pushed back until a workable age verification system can be put in place.

Since not everyone's comfortable handing over their credit card details to porn merchants, the British Board of Film Classification (BBFC) has proposed selling 'porn passes' at corner stores and newsagents, reports The Telegraph.

The 16-digit codes would cost around £10 (NZ$19.44), and shopkeepers would have to check the buyer's age, much like they do now for alcohol and cigarettes.

Director of technology at NetSafe Sean Lyons says it'll stop some kids, but not all.

"With any technological solution, there are also technological route-arounds," he told Newshub. "Eventually, somebody will work it out."

One simple method will be to use what's known as a VPN - a virtual private network - which makes it so your internet connection appears to be coming from a different country.

"Does this connection look like it comes from Britain? If so, switch on age verification," said Mr Lyons. "If it says it comes from the British Virgin Islands, they've got free rein."

Others include cheap prepaid credit cards and just plain hacking.

Hackers regularly 'crack' software that requires a code to install, offering piracy software known as 'keygens' - short for key generator - by figuring out the algorithm used to generate valid keys. It's not clear if any of the 'porn pass' systems would have workarounds for this, or be able to prevent 'brute force' hackers who use software to try every combination possible until one works.

The BBFC won't run the 'porn pass' system, but will ensure operators that do meet "high standards".

"We expect data security to be a high priority in the BBFC's guidance on age verification arrangements," a spokesperson told The Telegraph.

Mr Lyons believes the decentralised system will give kids several different ways to get in.

"There are different technologies that work in different ways, therefore there will be lots of different ways of getting around it."

And people might not be happy that private companies will be the gatekeepers to adult material online, even if the data is - in theory - anonymised.

"If we build these kinds of databases of people that are legitimately signing up for the use of adult content sites, every time I hear these stories it reminds me of what happens with Ashley Madison."

Ashley Madison was a dating site aimed at people looking to cheat on their partners, which two years ago suffered a devastating data leak - thousands of people's affairs being released online for all to see.

The 'porn pass' idea is currently undergoing public consultation.

Newshub.