With GoogleSharing,"what you're trying to protect are your searches ... that are only valuable in aggregate that paint a really big picture of who you are," Marlinspike said.
Anyone can run a GoogleSharing proxy server. Although those running one of those proxies would have access to the same information Google would have received, "those that are running a GoogleSharing proxy server are in a much worse position than Google to make use of that information," Marlinspike said.
If enough people run GoogleSharing proxies, queries could be distributed among all of the proxies, further diluting the information pool. The add-on can also be configured to use a specific proxy, he said.
"Your intent in using Google is not actually to share information with them," Marlinspike said. "When you're using Google you're not actually trying to give them your personal information. You're just trying to make use of the services."
Google did not have an immediate comment, although the company explains on its privacy pages that it keeps search engine data such as queries in order to improve the service and for the security of its systems.
Google introduced a dashboard in November 2009 that lets users see and manage some of the data that the company holds. But users must have an account to access that panel, and it doesn't show other information the company may have collected.