By Rowland Manthorpe, technology correspondent
From photography and home video to webcams and internet streaming, the next wave of technology has been often heralded by porn.
Today, that pattern is being repeated. Only this time the technology in question isn't a new way of consuming porn, but a new way of policing it - and it is driven not by sexual desire, but government regulation.
In less than two months, the UK will become the first country in the world to bring in age checks for online porn. Anyone visiting a porn website will be required to prove they are over 18, using a variety of methods (more on which later).Beset by poor planning and bad handling, porn block, as it is known, has been treated for the most part as a bizarre one-off, an online equivalent of Brexit. The New York Times called it "a distinctly British moral crusade".
That may be true. But the porn block is anything but a one-off. It is a testing ground for a system of digital identity checks, which could become an integral part of everything from internet shopping to social media.
A crucial - yet, strangely, barely recognised - milestone in the death of anonymity online. That might sound like an exaggeration. In fact, it's on its way to becoming government policy.
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Whereas the white paper addresses harms once they've happened, the code is designed to change the broken business model that produces them in the first place.
Its measures are ingenious and far-reaching. They include restricting the collection of data and limiting "nudge techniques" - a move which could spell an end to "likes" and "streaks" on social media.
Yet the most important aspect of the code - which is currently out for consultation, but expected to come into effect before the end of the year - is not its policy proposals, but the very idea that young people can be identified and treated differently online.
The ICO suggested a way to accomplish this. If tech firms couldn't treat everyone like young people, it said, then they should introduce a system to make sure young users didn't see anything they shouldn't.
The name for that system? Robust age verification. In other words: a porn block, only this time for the entire internet.
The word "robust" is significant. According to people familiar with its operations, the porn block is not intended to be impermeable. Rather than trying to prevent every young person seeing porn (something which would be impossible, short of confiscating computers from every teenager in the country), it will aim to keep out the majority; adding friction to a currently friction-less process.
A robust age verification system goes one further. Under this system, the barrier is designed to be inescapable. ID checks are built into the foundation of browsing.
The government is already rolling this out in other areas. On 7 May, it introduced strict age verification for online gambling. Now, gambling websites have to verify the name, address and date of birth of each customer - often more, as the gambling commission considers these requirements "a minimum".
Age checks are also being introduced for online sales of knives and alcohol. At present, big retailers "remind" customers - as if they didn't know - that knives and alcohol are age-restricted products.
As a barrier, it's hardly insurmountable. That's why the home office is exploring the use of, you guessed it, age verification technology. It's the perfect technological fix - if you're a minister.
"It is an area where more needs to happen, and more will happen," the CEO of one company in the field told me recently, as he ran me through his plan for rapid expansion."It'll be introduced for vaping, websites that sell alcohol, all the way through to places like Netflix and YouTube."
It will - as long the porn block proves successful. That is the key test. If politicians believe it's gone well, they'll happily extend age verification everywhere it will go.
Is this a problem? Libertarians won't like it; but then, they wouldn't. And for many parents, the introduction of age verification would come as a blessed relief.
But, on the internet, nothing is ever as easy as it seems. In the absence of digital ID cards, creating a robust age verification system often involves amassing an enormous store of personal data.Did you know, for instance, that the companies which set exams send your data to the government, which then passes it on for age verification? Or that data brokers such as Experian collect electoral roll and tax information for the same purposes?Privacy-protecting alternatives are emerging. One company, OCL, has created a "porn pass", which can be picked up in person, so no personal data is exchanged across the internet. Another, Yoti, promises to encrypt user data, so that even its employees can't see what's been entered. With demand growing swiftly, these firms are racing to do more. OCL is preparing to offer identity cards for students. Yoti is working with nightclubs, supermarkets and the government of Jersey. Both are aiming at one of the holy grails of technology entrepreneurs: to "own" identity on your smartphone. Listen to "Computer says no: The predictive algorithms that are changing lives" on Spreaker. :: Listen to New Lines on Apple podcasts, Google Podcasts, Spotify, Spreaker
And this is what gives me pause - because once you start to think about all the places digital ID checks could be introduced, and how powerful the companies that provide those checks would be, you realise how profound this shift is.
Thanks to its ill-conceived porn block, the government has quietly blundered into the creation of a digital passport - then outsourced its development to private firms, without setting clear limits on how it is to be used.Shouldn't there be a public debate before this happens? Shouldn't we be told? Or are we too busy being distracted by what Sajid Javid calls the "monsters" of the internet to notice what is happening right under our eyes?