The thing to know about Mr. White Hat is that he doesn’t use that name himself. The hacker, location unknown, has divulged few personal details, and who knows if those are even true? English isn’t his first language, he has said, and he’s a cybersecurity professional who’s been breaking into computers since he was young. That’s about it. (He also says he recently saw the movie Wrath of Man, the heist flick where Jason Statham kills a bunch of bank robbers, but that might be a joke.) What’s clear, though, is that he — or she, or they — is the force behind the $600 million heist of a lively but relatively obscure cryptocurrency project called Poly Network. The theft is the largest-ever crypto hack and highlighted the level of uncertainty and vulnerability in the exploding world of decentralized finance, or DeFi.