We're giving up privacy and getting no security in return!

Wired News - Mar, 09, 2006
Commentary by Bruce Schneier

In the post-9/11 world, there's much focus on connecting the dots. Many believe data mining is the crystal ball that will enable us to uncover future terrorist plots. But even in the most wildly optimistic projections, data mining isn't tenable for that purpose. We're not trading privacy for security; we're giving up privacy and getting no security in return....The promise of data mining is compelling, and convinces many. But it's wrong. We're not going to find terrorist plots through systems like this, and we're going to waste valuable resources chasing down false alarms. To understand why, we have to look at the economics of the system.

Data mining works best when you're searching for a well-defined profile, a reasonable number of attacks per year and a low cost of false alarms. Credit-card fraud is one of data mining's success stories: all credit-card companies mine their transaction databases for data for spending patterns that indicate a stolen card...Terrorist plots are different. There is no well-defined profile and attacks are very rare. Taken together, these facts mean that data-mining systems won't uncover any terrorist plots until they are very accurate, and that even very accurate systems will be so flooded with false alarms that they will be useless.

Data mining is like searching for a needle in a haystack. There are 900 million credit cards in circulation in the United States. According to the FTC September 2003 Identity Theft Survey Report, about 1 percent (10 million) cards are stolen and fraudulently used each year. When it comes to terrorism, however, trillions of connections exist between people and events -- things that the data-mining system will have to "look at" -- and very few plots. This rarity makes even accurate identification systems useless.

This is exactly the sort of thing we saw with the NSA's eavesdropping program: the New York Times reported that the computers spat out thousands of tips per month. Every one of them turned out to be a false alarm. And the cost was enormous -- not just for the FBI agents running around chasing dead-end leads instead of doing things that might actually make us safer, but also the cost in civil liberties.

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