USA Today‘s revelation that the National Security Agency has assembled a giant database containing hundreds of millions of business and personal phone records hit civil libertarians like a bomb.

But the news that the government stores a record of every incoming and outgoing call, the time it was made and its duration was welcomed by almost two-thirds of the country. Or so it would seem from the results of a Washington Post/ABC News poll.

The majority attitude is “no skin off my nose.” Since there cannot be more than a few score Al Qaeda agents in the entire United States, the general reaction to what a prickly minority of civil liberty fanatics considers a gross and illegal infringement has been the usual: “It doesn’t bother me. I have nothing to hide.” Which is true in a limited sense.

A few dozen would-be jihadists aside, nobody in the United States has anything to hide when it comes to plotting acts of mayhem, terrorism or any other violent political crime. But this gigantic body of information, which the government collects to discover what terrorists are up to, is just as useful in exposing other kinds of secrets.

For example, the program can be used to find out who of us is cheating on our wives, husbands or domestic partners. Vast numbers of people are doing something they do not want other people to know about, and if they are doing any part of it by telephone, the NSA operation can find out about it and use it against them.

Once you have a telephone number, a stroke or two on the computer will convert it to a name, and once you have a name, elementary data-mining will tell you all about the person behind the name. In a trice you will know that Bill has been calling Dr. So-and-So, a prostate cancer specialist, and that Harriet has been doing the same with a different kind of oncologist.

The possibilities for gaining information that is none of your beeswax is endless. People with a talent for doping things out should be able to make a stock-market killing by getting an early read on what companies are about to be bought or sold.

With this government data treasure hoard, it would be possible to find out whom a candidate for public office is trying to hit up for money–and to try to block the payment. It could be used by company executives to find out which of their employees are involved in the union organizing campaign–and to quietly get rid of them. It could be used for jury tampering, for unfair advantage in bidding for contracts, for tracking down reporters’ confidential sources, for anything where the telephone plays a large part–and that is almost everything.

Once USA Today‘s scoop hit the streets, President Bush rushed to the microphones to reassure whoever cared that “we’re not mining or trolling through the personal lives of millions of innocent Americans…. Our efforts are focused on links to Al Qaeda and their known affiliates.”

Our telephone calling patterns will be “fiercely protected” as long as nobody in the NSA leaks the telephone numbers. How comforting. The very existence of the NSA was supposed to be a secret. It was called No Such Agency until somebody leaked its existence. The NSA’s practice of eavesdropping on international calls was a deep dark secret until it got leaked. The telephone number database was a secret until it got leaked. If the government cannot protect its own privacy, no sensible person can give President Bush’s assurances any credence.

The leaking we hear about is evidently done by foolish people worried about historic American liberties. Those are the big-time leaks that have little to do with leaks that might reveal the results of testing a new drug, information that could send the stock of a pharmaceutical company flying up or down.

If your personal secrets or the commercial secrets of some company are leaked, it will likely be by government employees who do it for money. In the past few years we’ve had more than a spate of corruption in the Pentagon and in the intelligence services. These are cases we know of, but many of these agencies are not subject to any kind of public audit, so we are left to guess about how many dirty deals we may not know about. That’s one kind of secret they do manage to keep.