> Simple information theory; in a world of 6 billion people, 33 bits serves to uniquely identify anyone. 33 bits is a really low bar. It works because it can't hardly help but to work, sort of like the birthday paradox. In the US with approx 312 million (wikipedia) that's approximately 28.2 bits.

It's a powerful idea. I wrote a whole essay analyzing the anime _Death Note_ using the 33 bits idea (http://www.gwern.net/Death%20Note%20Anonymity) and I'm sure that's not even the tip of the iceberg.