In 1980, a young MIT professor named Silvio Micali @silviomicali asked a strange question during an informal conversation:

"Can I prove that I know something — without revealing anything about it?"

To answer it, he designed an interactive proof system: a multi-round challenge-response protocol where the verifier becomes convinced with high probability, without ever seeing the actual secret.

It was a probabilistic model of verification that broke away from static, traditional proof systems.