Metadata Can Expose Person’s Identity Even Without Name

Your shopping habits can expose who you are even when you are just one of a million nameless customers in a database of anonymous credit-card records, according to a new study that shows how so-called metadata can be used to circumvent privacy protections in commercial and government databases.

Researchers at the Massachusetts Institute of Technology, writing in the journal Science, analyzed anonymous credit-card transactions by 1.1 million people. Using a new analytic formula, they needed only four bits of secondary information -- metadata such as location or timing—to identify the unique individual purchasing patterns of 90% of the people involved, even when the data were scrubbed of any names, account numbers or other obvious identifiers.