Adding a third person to an encrypted conversation seems like it should be simple. It isn't. The cryptographic properties that make 1:1 messaging secure — forward secrecy, post-compromise security, deniability — become significantly harder to preserve as group size grows. When Signal introduced group chats, they faced a problem that doesn't exist in 1:1 messaging: how do you efficiently encrypt a
Part 2 of 5 in The New Engineering Contract - what it means to lead engineers when AI is doing more of the coding. Stripe never skipped the boring stuff. They ship 1,300 AI PRs a week. Amazon skipped it. Their storefront went down for six hours. Kent Beck wrote the answer in Extreme Programming Explained in 1999. We read it. Then chose velocity anyway. A friend of mine leads engineering at a funde