Personal privacy is in danger of being killed off by the profit-making motives of firms which hold our data, security expert Bruce Schneier has warned.
BT's chief technology officer expressed his concerns at the RSA Security Europe Conference in London.
While the death of personal privacy had been predicted for a long time, rapid technological changes posed a mortal danger to it, he said.
Mr Schneier urged lawmakers to do more to help preserve and protect privacy.
The death of privacy had been predicted before with the emergence of many different technologies, he said. But before now that threat had been largely overblown.
"Just because the technology is there does not mean that privacy invasions must happen," he said.
The difference now, he said, was that the falling cost of storage and processing power made it far easier to keep data such as e-mail conversations, Tweets or postings to a social network page than it was to spend the time managing and deleting the information.
The migration of human social interaction from ephemeral forms that took place face to face into data that never goes away and does not allow us to forget or leave behind our past actions was undoubtedly going to change society, he said.
"Forgetting is a very powerful social tool that helps us get by and get along," he said.
"That's new and fundamentally unnatural," he said.
Deciding what data we are prepared to surrender would be fine if people were given a proper choice, he said.
Unfortunately, he said, users of social networking sites or any online service were being presented with choices defined by priorities they did not choose.
The choices are filtered through the law, which is being outstripped by technological change, leaving people with only what net firms give them or can get away with.
"The social rules are being set by businesses with a profit motive," he said.
Facebook has faced a barrage of criticism about its privacy settings and despite effort to address user concerns, has continued to worry privacy campaigners.
Google boss Eric Schmidt said, after the row about its StreetView service scooping up wi-fi data: "If you have something that you don't want anyone to know, maybe you shouldn't be doing it in the first place."
Talking about privacy policies on web sites, Mr Schneier said they were hard to find and understand because it was in the interest of those sites to confuse people into disclosing more than they were comfortable with.
The more data about their members that sites gathered the better they can serve advertisers or use the data for their own marketing purposes, he said.
"We are now seeing the death of privacy," he said. "Those CEOs are doing it and doing things to hasten its demise."
In some senses, he said, this was not their fault because the production of data was a natural by-product of the way that computers work.
But, he said, this did not mean that legal and technological protections were not needed. The law was currently abdicating its role and there was a pressing need for tools that could help people manage their online presences.
He said that how we deal with privacy now would define how future generations regard us in the same way that commentators now look critically on the pollution produced as a by-product of the industrial revolution.
"They are going to look back at us and look at the things we do to deal with the pollution problem of the information age and judge us," he said.