An anonymous reader quotes a report from Ars Technica: A privacy advocacy group has filed a formal legal complaint with the Federal Trade Commission, asking the agency to begin an investigation "into Google's in-store tracking algorithm to determine whether it adequately protects the privacy of millions of American consumers." In the Monday filing, the Electronic Privacy Information Center (EPIC) said it is concerned with Google's new Store Sales Management program, which debuted in May. The system allows the company to extend its online tracking capabilities into the physical world. The idea is to combine credit card and other financial data acquired from data brokers to create a singular profile as a way to illustrate to companies what goods and services are being searched for online, which result in actual in-person sales. Because the algorithm that Google uses is secret, EPIC says, there is no way to determine how well Google's claimed anonymization feature -- to mask names, credit card numbers, location, and other potentially private data -- actually works. While Google has been cagey about exactly how it does this, the company has previously revealed that the technique is based on CryptDB.