It’s called zero-knowledge proof technology, and here’s how it works. Every few weeks, Americans get another letter in the mail that starts the same way: “We’re writing to inform you that your personal data has been exposed.” A retailer gets hacked. A hospital. A supermarket. A travel site. It never ends. Most of us feel like we’ve lost control over who has our information and how it’s being used. But a new kind of privacy technology, one that lets companies confirm what they need to know without ever seeing your personal details, may finally offer a way out of this mess.