messenger-encryption
The multi-year effort to make end-to-end encryption the default for personal chats and calls on Messenger, built on the Signal Protocol and Meta's own Labyrinth protocol for encrypted history.
Default end-to-end encryption for personal chats and calls, rolled out across Messenger in December 2023.
Messenger end-to-end encryption made encrypted personal chats and calls the default for more than a billion people, rather than an opt-in mode tucked inside a settings menu. Messages and calls are readable only on the devices of the people in the conversation, and Meta's servers cannot see their contents.
Delivering that required rearchitecting nearly every Messenger feature. In many cases, it also meant redesigning the experience so it could work without Meta's servers reading message content. Message transport runs on the Signal Protocol; encrypted history runs on Meta's own Labyrinth protocol, which stores ciphertext on Meta's servers that only the user's keys can open and keeps it in sync across devices. The rollout moved in stages, from testing encrypted backups in 2022 to the default launch in December 2023, with the feature set expanding in between.
Much of the design work was making strong cryptography feel routine rather than technical, from setting up a recovery PIN to managing which devices can read your history. The goal was for Messenger to feel familiar even as the architecture underneath it was rebuilt for privacy.