Microsoft to set time limit for storing data on Web searches

Microsoft is announcing changes to its privacy policy today that set a time limit on how long the company will retain data about customer queries through its search engine.

The policy, seen as an attempt to distinguish itself from Google, also allows people to opt out of targeted ads by third-party advertisers using Microsoft's Windows Live service.

Separately, Microsoft and Ask.com proposed that search providers, online-advertising companies and privacy advocates come up with a common set of global privacy practices for data collection and use.

"We have been thinking deeply about privacy related to search and online advertising and believe it is critical to evolve our privacy principles," said Peter Cullen, Microsoft's chief privacy strategist. "We're really focusing on: how do we be more transparent ... how do we give customers more control over what they want."

Microsoft will make all search-query data anonymous after 18 months, unless it receives consent to hold it longer, by permanently removing cookies, IP addresses or other information that links a specific customer to search terms, the company said.

The policy will apply retroactively and worldwide, Cullen said. Microsoft said the 18-month time period is the default, so people could opt in to allow their data to be retained longer.

The changes at Microsoft follow an announcement by Google last week that it would reduce the lifetime "cookies" — files that track people's Internet use — to two years. In March, Google also said search data stored on its servers would become anonymous after 18 months.

Tough European privacy regulations are looming for both companies. Europe's privacy directive states data no longer needed for the purpose it was collected must be deleted. The EU data-protection agency has criticized Google for holding on to user information too long.

Microsoft will retain the search data for 18 months for several reasons, Cullen said. Search engines rely on analyzing large amounts of data over time to deliver relevant results.

If you delete it too soon, "you don't improve the service," Cullen said.

Microsoft also relies on customer data to pay advertisers, and it maintains security by looking at data over time to pinpoint threats, he said.

Marc Hedlund, co-founder of Wesabe.com and a tech entrepreneur regarded as a privacy innovator, said Microsoft is making a good move to strengthen its privacy protections.

Large companies tend to do a bad job of keeping personally identifiable data separate from search terms.

"If Microsoft is going to do that, that's probably the single largest company I've ever heard of taking that approach," Hedlund said.

The key question, he said, is whether there's any way to re-associate search terms with personally identifiable data in the future, in response to a government subpoena, for example.

"If there's a way for an employee or a bad actor or a subpoena to force the association to occur, then, effectively, the association is still there," he said.

Cullen said that would not be the case. Once the histories are deleted, they cannot be retrieved, he said. "When we say 'anonymous,' we mean totally anonymous."

The company's decision to allow consumers to opt-out of third-party targeted ads sounds like a way to differentiate itself from Google, Hedlund said.

Microsoft also said it will develop new user controls to let people "search and surf its sites without being associated with a unique identifier used for behavioral ad targeting."

"Those are exactly the opt-out provisions that Google has refused to permit," Hedlund said.

Still, opting out of anything online has limited effectiveness for consumers, he added.

"Most of the time opt-outs don't work that well" because they're generally ignored and only used by people "who are extremely sensitive on these issues."

The changes also call for Microsoft to store search terms separately from account information such as a name, e-mail address or phone number.

Microsoft said it will improve protection to prevent the unauthorized correlation of such data and offer user consent before any service requiring search terms to be linked to identifiable account information.

Kristi Heim: 206-464-2718 or kheim@seattletimes.com