Google's new program to track shoppers sparks a federal privacy complaint

Google's program is hailed as a "revolutionary" breakthrough in tracking consumer behaviour. Photo / AP

A prominent privacy rights watchdog is asking the Federal Trade Commission to investigate a new Google advertising program that ties consumers' online behavior to their purchases in brick-and-mortar stores.

The legal complaint from the Electronic Privacy Information Center, to be filed with the FTC on Monday, alleges that Google is newly gaining access to a trove of highly-sensitive information -- the credit and debit card purchases records of the majority of US consumers -- without revealing how they got the information or giving consumers' meaningful ways to opt-out. Moreover, the group claims that the search giant is relying on a secretive technical method to protect the data - a method that should be audited by outsiders and is likely vulnerable to hacks or other data breaches.

"Google is seeking to extend its dominance from the online world to the real, offline world, and the FTC really needs to look at that," said Marc Rotenberg, the organisation's executive director.

Google called its advertising approach "common" and said it had "invested in building a new, custom encryption technology that ensures users' data remains private, secure and anonymous."

The Washington Post detailed Google's program, Store Sales Measurement, in May. Executives have hailed it as a "revolutionary" breakthrough in advertisers' abilities to track consumer behaviour. The company said that, for the first time, it would be able to prove, with a high degree of confidence, that clicks on online ads led to purchases at the cash register of physical stores.

To do this, Google said it had obtained access to the credit and debit card records of 70 per cent of U.S. consumers. It had then developed a mathematical formula that would anonymize and encrypt the transaction data, and then automatically match the transactions to the millions of U.S. users of Google and Google-owned services like Gmail, search, YouTube, and maps. This approach prevents Google from accessing the credit or debit card data for individuals.

But the company did not disclose the mathematical formula it uses to protect consumer's data. In a statement, Google said that it had taken pains to build custom encryption technology that ensures that the data the company receives remains private and anonymous.

The privacy organisation is asking the government not to not take Google's word for it and to review the algorithm itself. In its complaint, the organization said that the mathematical technique that Store Sales Measurement is based on, CryptDB, has known securityflaws. Researchers hacked into a CryptDB-protected healthcaredatabased in 2015, accessing over 50 per cent of the stored records.

Google also would not disclose which companies were providing it with the transaction records. When asked if users had consented to having their credit and debit transactions shared, Google would not specifically say. The company replied that it requires that its unnamed partners have "the rights necessary" to use this data.

In its complaint, reviewed by the Washington Post, the privacy group alleges that if consumers don't know how Google gets its purchase data, then they cannot make an informed decision about which cards not to use or where not to shop if they don't want their purchases tracked. The organisation points out that purchases can reveal medical conditions, religious beliefs, and other intimate information.

Google also told the Post that it does not have access to the names or other personal information of the credit and debit card users, and that it does not share any information about individual Google users with partners.

Advertisers receive aggregate information, for example, for an ad campaign for sneakers that received 10,000 clicks, the advertiser learns that 12 per cent of the clickers made a purchase.

Users can opt-out anytime, Google says. To do so, users of Google's products can go to their My Activity Page, click on Activity Controls, and uncheck "Web and Web Activity," Google says.

The privacy group says the opt-out settings and the descriptions of what users are opting out of are confusing and opaque. The group says that the company continues to store server and click data even when Web and App Activity is turned off, and that to opt-out of everything requires a labyrinthine process of going to a number of third party sites. Meanwhile, opting out of location-tracking requires going to a separate button and interface. None of the opt-out descriptions specifically describe credit card data.

In 2012 and in 2011, Google paid multi-million dollar fines to settle FTC charges on privacy issues. The 2012 case, for US$22.5 million, Google was charged with misrepresenting its privacy promises to users of Apple's Safari browser, who were the under the impression that they could opt-out of ad-tracking. In 2011, in response to a case brought by the Electronic Privacy Information Center, Google settled FTC charges that it used deceptive tactics and violated its own privacy promises when it launched its social network, Google Buzz.