Anonymous data not so anonymous after all


Like Hansel and Gretel’s trail of breadcrumbs, we all leave a trail of personal information as we navigate the internet.

Your friend sent you a birthday drink! A post about taxes in your hamlet, another about your toddler’s eating habits, a flight or hotel reservation, your Netflix queue… I think every internet user has a bit of a creeping bit of nervousness about what the web collective “knows” about their lives.

Ars Technica has an interesting post on this very subject today, summed up in a slightly jarring quote here:

“For almost every person on earth, there is at least one fact about them stored in a computer database that an adversary could use to blackmail, discriminate against, harass, or steal the identity of him or her. I mean more than mere embarrassment or inconvenience; I mean legally cognizable harm. Perhaps it is a fact about past conduct, health, or family shame. For almost every one of us, then, we can assume a hypothetical ‘database of ruin,’ the one containing this fact but until now splintered across dozens of databases on computers around the world, and thus disconnected from our identity. Reidentification has formed the database of ruin and given access to it to our worst enemies.”

Luckily for all of us, we’re Joe Average. The majority of us will never run for office or be in the headlines, but woe betide those of us who do. Google knows who you are, and it doesn’t keep secrets. Everyone laughed at Caribou Barbie Sarah Palin when some enterprising /b/tards youths hacked her e-mail account. But how secure are your security questions?

We all think we’re careful, not spilling an awful lot in public space and hey, my Facebook profile is set to private! (But as the ACLU pointed out not too long ago, our random FB tidbits also leak out through the profiles of our friends, of which I have over 150. I haven’t even met 150 people, in my life.) The linked Ars Technica article points out that even the benign stuff is not necessarily benign, when combined with other data that’s readily available. For instance, 87% of Americans are identifiable by birth date, zip code, and gender alone. How many places on the internet is that information readily available about you?

Perhaps the most worrying part is that information leakage seems to be trending toward being perpetuated forward but becoming relevant backwards. Let me explain with another anecdote from the article. In the mid-90s, a grad student in Massachusetts took an admittedly dopey initiative to study “anonymized” medical records data for all state employees to try to identify one. She was quickly successful in finding and delivering the Governor’s personal data to him:

Only six people in Cambridge shared his birth date, only three of them men, and of them, only he lived in his ZIP code. In a theatrical flourish, Dr. Sweeney sent the Governor’s health records (which included diagnoses and prescriptions) to his office.

So while you may be anonymous for now, bear in mind that almost unlike the fairly recent past, most of the information you release is leaving a trail. Could a forum post made in haste about a chronic cough affect your health coverage in 15 years? Could an old Netflix queue be used against you in court?

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