Somebody posted a note on Tuesday. Signed "Wayne." "We have a problem here." It would've been funny, except Wayne signed it with a private key that belongs to @eMudhra, a certificate authority in India. That key sits behind one of eight intermediate certificates your browser was built to trust. Hold one, and you can mint a valid certificate for any site on the internet. Your bank's login page included. So how did Wayne get it? Most people assumed a breach. An insider, maybe, or a spy agency. But he didn't steal anything. The keys were guessable. A normal P-384 key carries about 384 bits of randomness. That's a number 116 digits long, and nobody guesses that. The @eMudhra keys were 3 to 8 bits. One private key was literally the number 4. Another was 56. The biggest was 237. A laptop cracks all eight faster than you can finish this sentence. Filippo Valsorda, who maintains crypto code for Go, put it in the "this should not be possible" category. Ben Cartwright-Cox of https://t.co/Rg3ue0zZqK thinks example code slipped into production. And nobody noticed. Therefore browser makers moved fast. By late Tuesday morning, they had blocked all eight certs, along with some major apps and programming languages. Certificate transparency logs show no sign of anyone abusing the keys. Crisis over? Not even close. The browser was the easy part. Valsorda says this cleanup will be bigger than #Heartbleed, the 2014 OpenSSL bug that took years to mop up. The trouble is everything that ships its own copy of trusted roots and never updates: IoT gadgets, Docker containers, forgotten Linux boxes, old CLI tools. Some Linux distros didn't have fixes ready yet. Edge on Windows 10 was still connecting to 12 vulnerable hosts when Ars published. There's one catch for attackers. A bad cert only helps if you sit in the middle of someone's connection, decrypting and re-encrypting their traffic. That's hard on the open internet. It's a lot easier on coffee shop Wi-Fi, or in a country that already snoops on VPN traffic. Apps like Signal and WireGuard are fine, because they don't rely on TLS for privacy. Here's what bugs me. The lock icon in your address bar is not one company's promise. It's hundreds of companies promising at once, and it's only as strong as the sloppiest one. On Tuesday, the sloppiest one used a key of 4. Wayne told everyone. The next person might not. https://t.co/vSK9GTDYLa