For those who prefer transactions in cash, and would rather not reveal their name, it takes only three questions of the sort that are routinely and "innocently" asked online, and at the mall, to be pinpointed and identified effectively as individuals: gender, zip code and date of birth.

But your privacy is no better than that of one of Santa's reindeer if you are tethered to a smartphone, because it knows precisely where you are and quite a bit about what you are doing day and night, indoors and out. It's an appealing one-stop shop and information source for data collectors who crave to "connect the dots" between identity, address, shopping habits, phone records and real-time location. If you like to e-mail, tweet or text, it's also a ready directory of friends and an indication of online predilections and peccadilloes.

Yahoo and Google have been scanning the content, down to how you dot the last "i" and cross the last "t" in e-mail messages for years, though we are supposed to feel reassured that it is mostly machines, not gentlemen, reading our mail, and similar "protections" are said to be in place through the process of anonymizing PII, personally identifiable information, though this process is as leaky as human nature. Whenever an aggressive, profit-driven commercial giant says, "trust us" it's usually a good time to look for the nearest exit.

The way data miners and data exploiters get around the weak provisions of US law protecting PII is to mix and match partial data from different sources, collecting one type of data from one source, let's say a phone number, while getting another kind of data, let's say the anonymized content of your emails, or photos you've posted online, with things that interest you, as judged by your postings on Facebook, your "likes," your surfing habits and your search term profile.

Auto sales in both China and the US have been tainted by reports of misuse of personal data, which is not entirely surprising since cars are a big-ticket item, necessarily licensed and relatively easy to track, and often unwittingly reveal things about the owner.

The Wall Street Journal carried a telling story this month, "They know what you're shopping for" suggesting that one's effort to research autos online may backfire in the sense that the details of your search are available to the very salesmen you are hoping to negotiate with in your purchase of a new car. The more you try to learn about them, the more they know about you, even before you step into the auto showroom.

Just when you thought you had been long since liberated from the all-knowing gaze of the bearded dude in the red suit you find out that you are being tracked and rated in an eerily familiar, all-encompassing manner by people who want your money.

The alchemy of turning soft information into hard cash must appear outright magical, if not a bit spooky, to someone unacquainted with the latest snooping technology.

Happy holiday shopping! Ho, ho, ho!

The author is a visiting research fellow at Cornell University, New York.

(China Daily 12/28/2012 page9)