The Private Key Was Four

Every time a browser loads a page over HTTPS, it is trusting a chain of signatures. A certificate authority signs the website's certificate, and the browser accepts it because that authority sits on a short list the browser ships with. Most authorities keep their top-level root keys offline and do their daily signing with intermediates, subordinate keys the root has vouched for. Whoever holds an intermediate's private key can issue a certificate for any website, and browsers will accept it. So everything rests on the private key staying secret and unguessable. For the elliptic curve in this story, P-384, a private key is a number picked at random from a range about 116 digits long. No computer that will ever be built could search that range. In April 2025 eMudhra, a certificate authority based in India and trusted by Apple, Google, Microsoft and Mozilla, created a batch of new intermediates. The private key of one of them, EM OV TLS CA - G3C, was the number 4. Written out as a P-384…