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PrivacyProtecting web users’ privacy

By Larry Hardesty

Published 24 March 2017

Most website visits these days entail a database query — to look up airline flights, for example, or to find the fastest driving route between two addresses. But online database queries can reveal a surprising amount of information about the people making them. And some travel sites have been known to jack up the prices on flights whose routes are drawing an unusually high volume of queries. MIT researchers next week will present a new encryption system that disguises users’ database queries so that they reveal no private information.

Most website visits these days entail a database query — to look up airline flights, for example, or to find the fastest driving route between two addresses.

But online database queries can reveal a surprising amount of information about the people making them. And some travel sites have been known to jack up the prices on flights whose routes are drawing an unusually high volume of queries.

At the USENIX Symposium on Networked Systems Design and Implementation next week, researchers from MIT’s Computer Science and Artificial Intelligence Laboratory and Stanford University will present a new encryption system that disguises users’ database queries so that they reveal no private information.

The system is called Splinter because it splits a query up and distributes it across copies of the same database on multiple servers. The servers return results that make sense only when recombined according to a procedure that the user alone knows. As long as at least one of the servers can be trusted, it’s impossible for anyone other than the user to determine what query the servers executed.

“The canonical example behind this line of work was public patent databases,” says Frank Wang, an MIT graduate student in electrical engineering and computer science and first author on the conference paper. “When people were searching for certain kinds of patents, they gave away the research they were working on. Stock prices is another example: A lot of the time, when you search for stock quotes, it gives away information about what stocks you’re going to buy. Another example is maps: When you’re searching for where you are and where you’re going to go, it reveals a wealth of information about you.”

Honest broker
Of course, if the site that hosts the database is itself collecting users’ data without their consent, the requirement of at least one trusted server is difficult to enforce.

Wang, however, points to the increasing popularity of services such as DuckDuckGo, a search engine that uses search results from other sites, such as Bing and Yahoo, but vows not to profile its customers.