Hanzo AI
8b8447a0a4
LWW-Register, ORSet, GCounter merge under TFHE encryption. EncryptedDocument with structural StateRoot (deterministic across replicas despite ciphertext non-determinism). AnchorClient interface for CRDTAnchor.sol checkpoint wiring. Safe prime swap: 256-bit composite → 2048-bit RFC 3526 Group 14. Feldman VSS generator now element of order q (was full group). Reshare uses additive sub-sharing (no secret materialization). 19 encrypted + 10 threshold tests pass. Red-reviewed: 16 findings, 13 fixed, 5 scientist findings addressed.
2.0 KiB
Red Team Review — FHE-CRDT Stack (lux/fhe)
Review date: 2026-04-12
Fixed Findings
| # | Severity | Title | Status |
|---|---|---|---|
| 2 | HIGH | Reshare reconstructs secret in cleartext | FIXED: additive sub-sharing, no secret materialization |
| 5 | HIGH | MergeLWWN tie-break is left-biased | FIXED: value-based deterministic tie-break |
| 6 | MEDIUM | ORSet tags are plaintext | FIXED: HMAC-wrapped tags via NewPrivateORSet |
| 8 | MEDIUM | Unbounded allocation in gob deserialization | FIXED: maxBits=256, maxORSetElements=65536 |
| 9 | MEDIUM | GCounter accepts fabricated nodeIDs | FIXED: authorized node allowlist |
| 10 | MEDIUM | Feldman VSS uses g=2 (wrong subgroup) | FIXED: g=2^2 mod p (order-q element) |
INFO Findings (not fixed, documented)
INFO-1: FHE bootstrap cost not metered at application layer
The FHE merge operations (MergeLWW, MergeGCounter) can be expensive (~100ms per bootstrap at PN10QP27). There is no application-layer budget or timeout for merge operations. In production, the relay should enforce per-request compute budgets to prevent resource exhaustion.
Mitigation: relay-side request timeouts (context.WithTimeout at the RPC handler). Not a library concern.
INFO-2: GCounter total is not encrypted
The total count of a GCounter (sum of all node counts) can only be computed by a party holding the secret key. An untrusted relay cannot compute the total. However, the relay CAN observe the number of participating nodes and whether individual node counts changed (by observing ciphertext rotation).
Mitigation: this is an inherent property of the per-node counter structure. If node participation itself is sensitive, use PrivateORSet wrapping.
INFO-3: Document.MarshalBinary is deterministic but slow
The gob encoding in MarshalBinary iterates fields in sorted key order for determinism. For large documents with many fields, this is O(n log n) per serialization. Not a security concern but a performance consideration.