Whitfield Diffie

In 1976, Whitfield Diffie and Martin Hellman published a paper that opened with one of the most confident sentences in the history of engineering: “We stand today on the brink of a revolution in cryptography.” It was not hyperbole. For four thousand years, the entire practice of secret communication had rested on a single assumption so obvious no one had thought to question it—that to share a secret message, the sender and receiver must first share a secret key, delivered in advance through some trusted channel. Diffie proved the assumption false. He showed that two strangers could shout numbers at each other in full view of every eavesdropper and end the exchange in possession of a secret none of the listeners could compute, because the security rested on mathematical operations easier to perform than to reverse. This was not merely a clever trick. It was a redistribution of power: public-key