Pornhub will ask users to provide passport information or their mobile phone number in order to access the site when a new law comes into effect.
Mindgeek, which owns sites Pornhub, Redtube, YouPorn and Brazzers, is preparing to role out AgeID when the Digital Economy Act 2018 is implemented.
But the system has alarmed privacy campaigners who claims it could lead to an Ashley Madison-style leak.
Porn Site owner Pandora Blake said last year: 'You can imagine how much data that is going to give MindGeek, if they're going to have stats on what people click on, what porn sites people click on, what they pay for.
'Once you've got a MindGeek login, you're going to be giving them your entire web browsing history, because they're going to be able to track every time you log in to anything.'
In August 2015 millions of cheating spouses using the Ashley Madison infidelity website were outed after hackers leaked their personal details and sex fantasies.
Names, ages, addresses, phone numbers and credit card details of up to 37million users - including 1.2million in the UK - were laid bare in a 9.7 gigabyte file called 'Time's Up!' posted on the dark web.
Bankers, civil servants, UN peacekeepers and even Vatican employees were outed by hackers from the Impact Team because they are considered 'cheating dirtbags'.
Jim Killock Executive Director of the privacy group Open Rights Group added, 'The BBFC will struggle to ensure that Age Verification is safe, secure and anonymous. They are powerless to ensure people's privacy.
'The major publisher, MindGeek, looks like it will dominate the AV market. We are very worried about their product, AgeID, which could track people's porn use.
'The way this product develops is completely out of BBFC's hands. 'Users will not be able to choose how to access websites.
'They'll be at the mercy of porn companies. And the blame lies squarely with Theresa May's government for pushing incomplete legislation.'
But a MindGeek spokesman said the 'principles of privacy by designed' are at the core of the AgeID system.
The spokesnan added: 'AgeID has been built from the ground up with data protection, data minimisation and the principles of privacy by design at its core, while also complying with the GDPR.
'This is why we where do not store any personal data entered during the age-verification process.'
'Due to the encrypted nature of AgeID's login credentials, such data cannot be exposed in the unlikely event of a hack.'
However, critics argue the new law could lead to a large number of sites being blocked.
Online ID checks will require viewers prove they are 18 before viewing any porn online, as part of the Digital Economy Act 2018.
The system will be overseen by the British Board of Film Censorship but porn publishers will carry out their own age checks.
Users will need to make their AgeID account using a passport or mobile phone to confirm their age.
The information will then be passed to a government-approved service to confirm the user is over 18.
Porn sites which fail to ID users could be fined up to £250,000.
The Government will also be able to ask payment service to withdraw their support.
Mindgeek, which owns sites Pornhub, Redtube, YouPorn and Brazzers, is preparing to role out AgeID when the Digital Economy Act 2018 is implemented.
But the system has alarmed privacy campaigners who claims it could lead to an Ashley Madison-style leak.
Porn Site owner Pandora Blake said last year: 'You can imagine how much data that is going to give MindGeek, if they're going to have stats on what people click on, what porn sites people click on, what they pay for.
'Once you've got a MindGeek login, you're going to be giving them your entire web browsing history, because they're going to be able to track every time you log in to anything.'
In August 2015 millions of cheating spouses using the Ashley Madison infidelity website were outed after hackers leaked their personal details and sex fantasies.
Names, ages, addresses, phone numbers and credit card details of up to 37million users - including 1.2million in the UK - were laid bare in a 9.7 gigabyte file called 'Time's Up!' posted on the dark web.
Bankers, civil servants, UN peacekeepers and even Vatican employees were outed by hackers from the Impact Team because they are considered 'cheating dirtbags'.
Jim Killock Executive Director of the privacy group Open Rights Group added, 'The BBFC will struggle to ensure that Age Verification is safe, secure and anonymous. They are powerless to ensure people's privacy.
'The major publisher, MindGeek, looks like it will dominate the AV market. We are very worried about their product, AgeID, which could track people's porn use.
'The way this product develops is completely out of BBFC's hands. 'Users will not be able to choose how to access websites.
'They'll be at the mercy of porn companies. And the blame lies squarely with Theresa May's government for pushing incomplete legislation.'
But a MindGeek spokesman said the 'principles of privacy by designed' are at the core of the AgeID system.
The spokesnan added: 'AgeID has been built from the ground up with data protection, data minimisation and the principles of privacy by design at its core, while also complying with the GDPR.
'This is why we where do not store any personal data entered during the age-verification process.'
'Due to the encrypted nature of AgeID's login credentials, such data cannot be exposed in the unlikely event of a hack.'
However, critics argue the new law could lead to a large number of sites being blocked.
Online ID checks will require viewers prove they are 18 before viewing any porn online, as part of the Digital Economy Act 2018.
The system will be overseen by the British Board of Film Censorship but porn publishers will carry out their own age checks.
Users will need to make their AgeID account using a passport or mobile phone to confirm their age.
The information will then be passed to a government-approved service to confirm the user is over 18.
Porn sites which fail to ID users could be fined up to £250,000.
The Government will also be able to ask payment service to withdraw their support.
