White Noise
White Noise is a private group-messaging application built on Marmot Protocol. Marmot supplies the protocol profile; White Noise supplies a user-facing client, local key and state handling, relay interaction, encrypted media, notifications, and account lifecycle.
Encryption boundary
White Noise uses Messaging Layer Security for authenticated group state, forward secrecy, and post-compromise recovery. Each device is represented by a separate MLS leaf. Marmot group events use fresh ephemeral Nostr signing keys and carry an MLS message inside an additional ChaCha20-Poly1305 envelope. Encrypted media is stored through configurable Blossom servers.
The default MLS ciphersuite uses X25519 key agreement, AES-128-GCM authenticated encryption, SHA-256 hashing, and Ed25519 signatures. These are strong classical primitives, but the profile does not currently provide post-quantum key agreement.
Metadata boundary
Relay operators cannot read message content. Ephemeral outer signing keys avoid placing a sender’s long-term Nostr key directly on each group event. The outer event nevertheless contains a stable group-routing tag, and relays can observe IP addresses, subscriptions, message timing, size, and encrypted-event persistence. Ephemeral keys therefore reduce direct identity exposure; they do not provide network anonymity by themselves.
Evidence and maturity
Least Authority reviewed the Marmot specification in November 2025, the Marmot Development Kit in March 2026, and the White Noise Rust backend in April 2026. The implementation audits found critical identity, authorization, local-storage, and group-state defects; the published verification reports mark the critical findings as resolved. One high-severity reusable-KeyPackage finding remained unresolved in the MDK audit, and the application audit left dependency updating partially resolved.
This is meaningful security work, but it also places White Noise in a different maturity class from Signal. The application and wire profile remain young, have recently made breaking changes, and have much less deployment and adversarial history.
White Noise and Marmot security reviews preserves the review artifacts and their scope.