Technical specification for the NullWire anonymous communication protocol. Version 0.4 — April 2026. Loopix mixnet architecture, Sphinx packet routing, Solana control plane, cryptographic stack, and threat model.
Messages are routed through Sphinx packets — fixed 2048-byte size, 3-hop relay path, configurable Poisson delays. Cover traffic architecture built in. An adversary watching the network cannot trivially correlate sender to receiver by timing or packet size. Proven cross-device on devnet.
Node registry, admission, and liveness attestation live on-chain. No central server. No kill switch. No seizure point. 2-of-3 validator-backed admission. Multi-RPC quorum validation — clients verify directory snapshots across independent endpoints before route construction.
No phone number. No email. No persistent identifier required by the transport layer. Planned: Groth16 ZK proof of legitimacy — the network verifies you are a real user without learning who you are. Not yet implemented — deferred to post-alpha.
Current: ML-KEM-1024 + X25519 hybrid key exchange (FIPS 203) — post-quantum protection on initial key agreement. HKDF-SHA3-256 (FIPS 202) key derivation.
Current: X3DH-style bootstrap + Double Ratchet-style E2E — key zeroization, skipped key expiry (48h), state file permissions, session reset with peer notification.
Current: Sphinx packet encryption — constant size, unlinkable across hops.
Next: Contact discovery, persistent state encryption, third-party cryptographic review.
| Attack | Defense | Status |
|---|---|---|
| Timing correlation | Poisson delays + cover traffic at every hop. Fixed 2048-byte packet size eliminates size correlation. | ARCHITECTURAL |
| Sybil attack | Validator-backed admission (2-of-3 quorum). Nodes cannot join routing without approval. | LIVE |
| Route poisoning via RPC compromise | Multi-RPC quorum: k-of-n agreement across independent RPC endpoints before path construction. One compromised RPC cannot poison route. | CLI PATH DEFAULT — PENDING |
| Message content interception | ML-KEM-1024 hybrid + Sphinx routing layer. X3DH-style bootstrap + Double Ratchet-style E2E with key zeroization, session management, HKDF-SHA3-256 key derivation. Pre-alpha with significant hardening. Pending: contact discovery, external audit. | PRE-ALPHA |
| Mailbox access pattern exposure | Gateway currently sees mailbox polling patterns. Sealed mailbox / PIR planned for later phase. | LATER PHASE |
| Global passive adversary | Not proven at current network size. Requires meaningful anonymity set. Loopix architecture designed for this — effective only with sufficient traffic volume. | SCALE DEPENDENCY |
Sphinx-routed 3-hop delivery across two physical machines on devnet. Not localhost theatre — real separate-device proof.
2-of-3 validator quorum required before any node becomes routable. Wrong-operator attestations rejected. Promotion after extra approval proven.
Client-side k-of-n RPC agreement before route construction. Single-RPC poisoning attack proven to fail under quorum failure test.
Fast: ~211ms median. Balanced: ~503ms median. Private: ~1.25s median. 28 msg/sec throughput on one host (localhost baseline).
X3DH-style key agreement bootstrap proven between two parties in cross-device test. Forward secrecy key material established from first message exchange. ML-KEM-1024 hybrid key exchange + HKDF-SHA3-256 key derivation implemented. Pre-alpha with significant hardening — not yet externally audited.
Double Ratchet-style per-message key ratchet proven in prototype. Forward secrecy per message — compromise of one session key does not expose prior messages. Key zeroization on drop, skipped key expiry (48h), session reset with peer notification. Pre-alpha with significant hardening — not yet externally audited.
End-to-end encrypted messages delivered across two separate physical machines on devnet. Sphinx routing privacy + X3DH/Double Ratchet E2E + ML-KEM-1024 hybrid key exchange + HKDF-SHA3-256 key derivation. Pre-alpha with significant hardening — not yet externally audited.