Google is changing its data retention practices to make it harder to identify the specific computers used in searches.
Google's servers log information every time someone conducts a Web search, keeping data such as the keywords used, the Internet Protocol address or unique number assigned to that person's computer, and information from Web cookies, which are small bits of data exchanged between a server and a Web browser each time the browser accesses the server. Cookies are used to authenticate the user and maintain information such as the user's site preferences.
Currently, Google maintains the search data logs indefinitely. Under the new policy announced on Wednesday, which Google expects to have fully implemented by the end of the year, the company will anonymize the final eight bits of the IP address and the cookie data after somewhere between 18 months and 24 months, unless legally required to retain the data for longer. The information on specific searches will remain indefinitely, but it will be much harder to tie the searches to specific individuals or computers.
"Logs anonymization does not guarantee that the government will not be able to identify a specific computer or user, but it does add another layer of privacy protection to our users' data," the company said.
The policy change will apply to future Web search data as well as archived logs and all copies of the data stored on other servers, Google said. Users will be able to opt out of the practice and request that their search data be maintained indefinitely.
Privacy advocates in general said Google's policy change is a step in the right direction but not nearly enough to really protect Web searchers from overzealous law enforcers. Keeping the search histories could enable investigators and governments to get to all sorts of personal information about people, they argue.
"I don't think the Google proposal is adequate. This period is too long and it's not in fact data destruction, it's more data de-identification, and that should be happening in 18 to 24 hours, not months," said Marc Rotenberg, executive director of the Electronic Privacy Information Center. "I'm not persuaded that this isn't still a ticking time bomb for Google's search engine."
Richard M. Smith, an Internet security and privacy consultant at Boston Software Forensics, said Google should never be archiving the IP address and cookies on servers. "Google should not be in the spy business," he said. "By logging IP addresses and search strings they are running the largest intelligence operation in the world."
Anonymizing the last eight bits of the IP address effectively would enable investigators to narrow the IP address down to 256 possible computers or users. That would be similar to obscuring the last digit in someone's street address.
"Google should not be in the spy business. By logging IP addresses and search strings they are running the largest intelligence operation in the world."
--Richard M. Smith, consultant, Boston Software Forensics
"For most average consumers that is pretty much anonymous," because many people connect to the Internet through large companies that dynamically assign IP addresses, making it even harder to determine exactly which person conducted a search, said Ari Schwartz, deputy director for the Center for Democracy and Technology. "It is a risk, but it is better than what we have today."
Kevin Bankston, staff attorney at the Electronic Frontier Foundation, said he would like to see Google scrub the entire IP address within six months, but praised Google for making this "positive first step."
"We hope other online service providers will heed this example and work to minimize the amount of data they keep about their customers," Bankston said.
Yahoo and Microsoft have declined to disclose their exact data retention policies with respect to Web searches. AOL saves personally-identifiable search data for up to 30 days in a way that's visible to the user and uses an encryption hashing technique to obscure it thereafter, said AOL spokesman Andrew Weinstein.
"We do not keep any IP addresses in our search database, and we de-identify any associated account information through an encryption algorithm," he said. "We have also made a business decision not to keep any unique identifiers (i.e. the hashed user ID) for longer than 13 months. ..."That said, it still might contain information of a personal nature, as the data released last year clearly did."
The risks associated with Web search data were highlighted last August when AOL inadvertently exposed on the Internet the search history of more than 650,000 of its users. The move prompted widespread criticism from privacy advocates and Congress and the filing of a complaint against AOL with the Federal Trade Commission, as well as the firing of two AOL employees and the resignation of its chief technology officer and a class action lawsuit.
The lawsuit was later dismissed because AOL's user agreement requires lawsuits filed against it to be filed in its home state of Virginia, said Bankston.
Google said it can't anonymize the entire IP address, delete it altogether or anonymize any of it sooner than 18 months because it needs the data to analyze usage patterns and diagnose system problems. For example, Google uses the information for fraud detection and prevention and to combat denial of service attacks that can temporarily cripple or shut down servers. "Knowing what country a user is coming from helps us figure out whether or not we are delivering the right search," said Nicole Wong, deputy general counsel for Google.
Why wait 18 to 24 months?
The proposed timeframe for retaining the data in identifiable form was chosen because data retention laws in Europe require communications service providers to hold on to the information for that long, according to Wong.
If governments in various countries enact legislation to require communications service providers to archive Internet traffic for specific lengths of time including up to four years, as some are considering, Google would then have to abide by the laws, the company said. Law enforcement will still be able to subpoena server log data after it is anonymized, but every request will be considered on its merits and Google's response will depend on how narrow the request is and how relevant the data is to the investigation, Google said.
However, EPIC's Rotenberg said two years is that "top end" of the timeframe European governments are seeking for requiring communications service providers retain user data.
Google said it is making the changes in response to feedback from privacy activists and others, including the Norwegian Data Protection Authority with which Google executives met in January. A team of Google executives, engineers and lawyers were involved in establishing the new policy, Wong said.
Of all the major search engines, Google is the only one to publicly disclose that it has fought government efforts for consumer data. A year ago, Google challenged a subpoena received by the U.S. Department of Justice that ordered Google to hand over a random sample of a week's worth of search terms and one million Web pages from its index to aid in the Bush administration's defense of an Internet pornography law. One month later a federal judge sided mostly with Google and ordered the company to provide half of the amount of Web pages sought but none of the search queries.
The new policy would not have affected that situation because the government was not asking for searches tied to individual IP addresses, Wong said.