Privacy

Some years ago, I made a thing that could determine whether two different player characters in an online game with global chat were likely to be the same person by using a classification algorithm on their public chat. The popular text classification algorithms at the time didn't work very well for that use case, but I came up with one that did. It was fun and useful that my internet friends and I could know who we were dealing with when they thought they were being sneaky.

I read that DARPA was offering grants for exactly that kind of work, and thought up several ideas for commercializing the technology. Then I did exactly none of that because privacy is good and accelerating the availability of de-anonymization technology is bad.