Freebird Security Documentation¶

Freebird is pre-1.0 software. Public deployments are experimental and must be reviewed against the operator's own threat model, configuration, and operational controls. The project has not had an external security audit.

This section separates what the current implementation is intended to do from deployment assumptions, known limits, and future work. It is not a security certification, a production-readiness statement, or a promise of anonymity.

Pages¶

Threat model — actors, assets, security properties, threats, assumptions, and non-goals.
Privacy properties — the token-layer privacy claim and the metadata that remains visible to surrounding systems.
Non-goals — claims Freebird does not make.
Cryptographic assumptions — the assumptions behind the current V4 and V7 token flows, without claiming formal proof or interoperability.
Audit status — current review status, operational logging, and known security exceptions.

Current boundary¶

The current issuance API is transitional and experimental. V4 uses a Freebird-specific bespoke P-256 VOPRF-like construction and is not RFC 9497 interoperable. V7 uses randomized RSA blind signatures and issuer-published discovery metadata. In both cases, the client obtains a blinded issuance result, finalizes a token, and the verifier checks and consumes a replay identity or nullifier.

Optional Sybil mechanisms are issuer admission controls. They can raise cost, apply local quotas, or require configured credentials, but none proves global human uniqueness. A weak or disabled Sybil configuration can allow token farming even when token verification works as intended.

Operational minimum¶

For an internet-exposed deployment, the repository security guidance calls for TLS, a high-entropy admin key, protected key and state storage, Redis-backed verifier nullifiers, and Redis-backed Sybil-proof replay protection. In-memory replay storage is an explicitly unsafe development option: verifier nullifiers are lost on verifier restart, and the default Sybil replay store is process local unless configured otherwise.

See the root Security Policy and the repository's existing deployment and Sybil documentation for configuration details.