Labyrinth 1.1: Making End-to-End Encrypted Backups Even More Reliable

Why Labyrinth 1.1 Changes How Message Backups Work

Meta has released version 1.1 of Labyrinth, the encrypted storage system and protocol that secures messages and history on Messenger. The update improves the reliability of end-to-end encrypted (E2EE) backups by introducing a sub-protocol designed to keep messages safe when a device is lost, when users switch devices, or after long gaps between sign-ins.

Since encrypted backups were launched for Messenger in 2023, message history has been protected with end-to-end encryption so it can move across devices without being readable by any other party, including Meta. With Labyrinth 1.1, the key change is timing: messages reach the encrypted backup as they are sent, rather than waiting for the device to come back online, which is how current Messenger encrypted backups operate.

How the New Sub-Protocol Works

The new approach wraps each message with a message encryption key that the sender places directly into the recipient’s encrypted backup. The described mechanism is akin to dropping a sealed envelope into a locked box that only the recipient can open. This ensures messages are preserved even if the recipient’s device is unavailable or permanently lost.

The result is that no one other than the sender and the intended recipient can read the messages—including Meta. By shifting backup creation to the moment of sending, Labyrinth 1.1 avoids the dependency on device availability that previously left gaps in backup coverage.

Deployment and Impact

Meta is rolling Labyrinth 1.1 out broadly to Messenger. Early results show meaningful gains, with more messages successfully backed up and more users restoring their full message history when moving to a new device.

Further Reading

For a complete technical description, see the updated white paper, “The Labyrinth Encrypted Message Storage Protocol.”