Google collects a vast amount of information about its users, said Marlinspike, who gave a presentation at last week's Black Hat conference. The company collects IP (Internet protocol) addresses, search requests, browser type and more.
Google as well as other major search companies have taken steps to allay concerns over data collection, such as anonymizing parts of IP addresses held in their records after certain periods of time. But Google dictates how it anonymizes information that could potentially be collated later to profile a user, Marlinspike said.
With IP addresses, for example, Google anonymizes the last octet of the address after nine months, Marlinspike said. Some privacy advocates argue that does not go far enough. Google also uses cookies, or data files stored by a browser, to associate search queries with a particular installation of a browser on a given computer.