This is the story of a bug that was discovered and fixed in Telegram's self-rolled cryptographic protocol about seven years ago. The bug didn't get any press, and no one seems to know about it, probably because it was only published in Russian. To this day, it's the most backdoor-looking bug I've ever seen. Google Translate does a good enough job on the original article, which is still available on Habr, but I'm going to walk you through it along with some context. Telegram is a popular chat app...