When we started working on this we absolutely did not want to build a hardware device. Option one was some form of biometrics, like what you use at the airport or for Face ID. But those are for reauthentication—one-to-one comparisons. Proof of human requires uniqueness—one-to-n comparisons across all users. Mathematically, face doesn’t have enough information; fingerprints don’t either. Iris was the most promising modality that could scale to billions—and, combined with cryptography, stay anonymous. We also assumed the next major computing platform would be AR/VR [augmented reality / virtual reality], where iris could become the new Face ID. In the next five to ten years, iris may be the default for logging in on glasses and accounts.

Joanna Stern, I Am Not a Robot- My Year U…, loc. 1179