Netflix anonymous data is not so anonymous...

It amazes me that people still think they have a veil of anonymity online anymore. I'm reminded of the AOL searches that were made public last year; although AOL assured the public that individuals could not be identified, of course it was possible to determine personal information like names, addresses, etc.

Luckily, I don't mind who knows that I'm radical...Four stars to Fahrenheit 9/11!

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"Of course, Netflix assured everybody that the data had been anonymized by removing any personal details.

That turns out to have been a tad optimistic. Arvind Narayanan and Vitaly Shmatikov at the the University of Texas at Austin have just de-anonymized it.

Here’s how: turns out that an individual’s set of ratings and the dates on which they were made are pretty unique, particularly if the ratings involve films outside the most popular 100 movies. So it’s straightforward to find a match by comparing the anonymized data against publicly available ratings on the Internet Movie Database (IMDb).

....

Here’s what the dynamic duo have to say about one person whose data they outed:

“First, we can immediately find his political orientation based on his strong opinions about “Power and Terror: Noam Chomsky in Our Times” and “Fahrenheit 9/11.” Strong guesses about his religious views can be made based on his ratings on “Jesus of Nazareth” and “The Gospel of John”. He did not like “Super Size Me” at all; perhaps this implies something about his physical size? Both items that we found with predominantly gay themes, “Bent” and “Queer as folk” were rated one star out of five. He is a cultish follower of “Mystery Science Theater 3000”. This is far from all we found about this one person, but having made our point, we will spare the reader further lurid details. “

So Netflix may have inadvertently revealed the political affiliation, sexual orientation, BMI and God-knows-what else of 500,00 of their subscribers. Way to go!"

http://arxivblog.com/?p=142