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zeekayandHanzo Dev
d029323697
Fast-follow hardening of the per-height vote-once fork fix (v1.33.2). Red's
re-review found three residuals that leave post-crash equivocation reachable;
this closes all three and adopts Red's harness-free suite as the standing gate.
HIGH-1 — PERSIST committedSlot. The guard was an in-memory map: a crash/restart
between casting a vote and finalizing the height forgot every unfinalized binding,
so the restarted node could sign a conflicting sibling → a cross-node fork with
ZERO Byzantine intent under a rolling upgrade / k8s eviction / OOM. New
vote_guard.go adds a durable VoteGuardStore (Tendermint priv_validator_state.json
pattern): the (height,epoch)→canonical binding is fsync'd BEFORE the signature is
cast (reserveSlotForSign returns true only after the durable write commits — a
write failure FAILS CLOSED) and reloaded on startup (WithVoteGuard seeds
committedSlot). The one concrete store is an atomically-replaced, crc32c-checked
snapshot file (write-temp → fsync → rename → fsync-dir); a corrupt file is a hard
error at open (a signer must not start with equivocation memory it cannot trust).
HIGH-2 — key (height,epoch), matching the consensus2 reference (SlotKey={height,
epoch}). epoch = the block's ValidatorSetRoot, already folded into the signed vote
message. Height-only keying is SAFE but can STALL a quorum at a validator-set
change (a contested height re-proposed under a new epoch is refused by everyone who
signed the old-epoch block). Cross-epoch safety is preserved independently by the
per-height finalize gate (ErrHeightAlreadyFinalized) plus the induction that the
set at a height is a function of the uniquely-finalized lower chain. A fixed-set
chain leaves epoch=Empty, so the slot degrades to height-only (backward-safe).
MEDIUM-1 — fix the prune leak. pruneCommittedSlotsBelow ran ONLY from
HandleIncomingCert, which the dominant LOCAL finalize path never reaches (it
short-circuits at pending.Decided). Moved the prune into the sole finalizer
acceptWithCertCore (beside pruneSlashingBelowWindow), the one funnel EVERY finality
path shares, so committedSlot stays bounded on every validator; removed the now-
redundant HandleIncomingCert prune.
Tests (all -race): Red's red_independent_fork_test.go adopted verbatim as the gate
(mechanical API adaptations only — epoch arg, SlotKey; leak test promoted from Skip
to a hard MEDIUM-1 assert); TestBlue_VoteGuard_CrashRestart proves a reopened store
refuses a sibling after a simulated crash; TestBlue_CrossEpochLiveness_NoStall
proves no stall at a set-change boundary while intra-epoch safety holds;
fail-closed / corrupt-file / round-trip store gates; a multi-round down-proposer
liveness test with an ACTIVE short RoundTO (fork-fix × liveness-fix interaction).
Verified: neutering the guard flips OwnVoteRefusedForSibling + equivocators=2 RED
(teeth); full engine/chain suite green; 50× emergent fork probe = 0 forks.
Co-authored-by: Hanzo Dev <[email protected]>
Lux Consensus
Lux is not merely adding post-quantum signatures to a chain; it defines a hybrid finality architecture for DAG-native consensus, with protocol-agnostic threshold lifecycle, post-quantum threshold sealing, and cross-chain propagation of Horizon finality.
See LP-105 §Claims and evidence for the canonical claims/evidence table and the ten architectural commitments — single source of truth.
Quasar Family of Consensus
Quasar is the consensus engine for the Lux network. It provides unified consensus for linear chains (P-Chain, C-Chain) and DAG chains (X-Chain) with post-quantum finality via three independent cryptographic signing paths.
Sub-Protocols
| Protocol | Role | Package |
|---|---|---|
| Photon | K-of-N committee selection via Fisher-Yates sampling with luminance-weighted reputation | protocol/photon |
| Wave | Per-round threshold voting with FPC (Fast Probabilistic Consensus) | protocol/wave |
| Focus | Confidence accumulation: beta consecutive successes = local finality | protocol/focus |
| Nova | Linear chain consensus mode (P-Chain, C-Chain) -- wraps Ray | protocol/nova |
| Nebula | DAG consensus mode (X-Chain) -- wraps Field | protocol/nebula |
| Prism | DAG geometry: frontiers, cuts, uniform peer sampling | protocol/prism |
| Horizon | DAG order-theory: reachability, LCA, transitive closure, skip lists | protocol/horizon |
| Flare | DAG certificate/skip detection via 2f+1 quorum | protocol/flare |
| Ray | Linear chain finality driver: Wave + Focus + Sink | protocol/ray |
| Field | DAG finality driver: Wave + safe-prefix commit | protocol/field |
| Quasar | BLS + Pulsar + ML-DSA threshold signing, epoch management | protocol/quasar |
Signing Modes
Each cryptographic layer is independently toggleable:
| Mode | Layers | Use Case |
|---|---|---|
| BLS-only | BLS12-381 threshold | Fastest classical consensus |
| BLS + ML-DSA | BLS + FIPS 204 ML-DSA-65 | Dual with PQ identity proof |
| BLS + Pulsar | BLS + Ring-LWE 2-round threshold | Dual with PQ threshold proof |
| BLS + Pulsar + ML-DSA | All three in parallel | Full Quasar (triple mode) |
IsTripleMode() returns true when all three paths are configured.
TripleSignRound1 runs BLS + Pulsar + ML-DSA signing in parallel goroutines.
PQ Mode Selection (Configurable)
The active mode is selectable at runtime via config.PQMode or the
CONSENSUS_PQ_MODE env var. Defined in config/pq_mode.go:
| Mode | Env value | Maps to wire policy |
|---|---|---|
BLSOnly |
bls |
PolicyQuorum |
BLSPlusMLDSA |
bls-mldsa |
PolicyPQ |
BLSPlusCorona |
bls-rt |
PolicyPZ |
BLSPlusGroth16 |
bls-z |
PolicyQuantum (placeholder) |
TripleQuantum |
triple |
PolicyQuantum |
Run bench/pq_modes_bench_test.go for measured per-mode signing /
aggregation / verify costs and cert sizes. Storage and cert size
trade-offs:
| Mode | Sign | Agg | Verify | Cert | Storage 10K |
|---|---|---|---|---|---|
| bls | 312 µs | 8.6 ms | 714 µs | 123 B | 1.17 MB |
| bls-mldsa | 369 µs | 8.5 ms | 3.4 ms | 69 KB | 665 MB |
| bls-rt | 39 ms | 3.3 s | 1.6 ms | 33 KB | 318 MB |
| triple | 40 ms | 3.3 s | 4.3 ms | 102 KB | 981 MB |
Pulsar / triple include the full 2-round Pulsar threshold protocol
(github.com/luxfi/pulsar/threshold — Pulsar is Lux's variant with
DKG2 and Pulsar-SHA3 hash suite). Production parameters M=8, N=7,
LogN=8 (ring degree 256), Q=2^48-ish: classical 2^142, quantum 2^130.
Cert-size floor of ~33 KB is set by the (C, Z, Delta) ring polynomials;
protocol/quasar/cert_size_compare_test.go measures and verifies this.
Architecture
consensus/
protocol/
photon/ Committee selection (Emitter + Luminance)
wave/ Threshold voting + FPC
fpc/ Fast Probabilistic Consensus selector
focus/ Confidence counter (beta tracker)
prism/ DAG cuts, frontiers, uniform sampling
horizon/ DAG reachability, LCA, skip lists
flare/ DAG cert/skip classification (2f+1)
ray/ Linear chain driver (Nova uses this)
field/ DAG finality driver (Nebula uses this)
nova/ Linear chain consensus mode
nebula/ DAG consensus mode
chain/ Block interface primitives
quasar/ BLS + Pulsar + ML-DSA threshold signing
engine/ Consensus engine (Chain, DAG, PQ wrappers)
core/ Core types, DAG structures
types/ Block, Vote, Config, Bag
config/ Parameter presets (single, local, testnet, mainnet)
runtime/ VM wiring (chain IDs, validators, logging)
pkg/wire/ Wire protocol credentials (ML-DSA-44/65/87 + BLS + Ed25519)
bench/ Benchmarks
version/ Re-exports github.com/luxfi/version
Consensus Flow
Linear Chains (Nova)
Photon (select committee) -> Wave (threshold vote) -> Focus (count beta) -> Ray (decide) -> Sink
DAG Chains (Nebula)
Photon (select committee) -> Wave (threshold vote per frontier vertex)
-> Flare (cert/skip) -> Horizon (safe prefix) -> Field (commit ordered prefix) -> Committer
Quasar PQ Finality
After consensus decision, the Quasar signing layer produces threshold certificates:
- BLS: single-round threshold share via
crypto/threshold - Pulsar: 2-round Ring-LWE threshold via
luxfi/corona/threshold - ML-DSA-65: single-round FIPS 204 identity signature
All three run in parallel. A block is quantum-final when all configured certificate layers are valid.
Key Hierarchy
| Layer | Key Type | Purpose |
|---|---|---|
| Node-ID | Ed25519 | P2P transport auth |
| Validator-BLS | BLS12-381 | Classical finality votes |
| Validator-PQ | Pulsar (Ring-LWE) | PQ finality shares |
| Validator-ID | ML-DSA-65 (FIPS 204) | PQ identity attestation |
| Wallet (EVM) | secp256k1 | User transaction signatures |
| Wallet (X-Chain) | secp256k1 | UTXO locking |
Quick Start
import "github.com/luxfi/consensus"
chain := consensus.NewChain(consensus.DefaultConfig())
ctx := context.Background()
if err := chain.Start(ctx); err != nil {
log.Fatal(err)
}
defer chain.Stop()
block := &consensus.Block{
ID: consensus.NewID(),
ParentID: consensus.GenesisID,
Height: 1,
Payload: []byte("Hello, Lux!"),
}
if err := chain.Add(ctx, block); err != nil {
log.Fatal(err)
}
Configuration
// Auto-configure based on validator count
params := consensus.GetConfig(21) // mainnet defaults
// Or use presets
consensus.SingleValidatorParams() // 1 node, dev
consensus.LocalParams() // 5 nodes, local
consensus.TestnetParams() // 11 nodes, testnet
consensus.MainnetParams() // 21 nodes, production
Benchmarks
Measured on Apple M1 Max:
| Component | Operation | Time/Op |
|---|---|---|
| Wave | Vote round | 3.38 us |
| Photon | K-of-N selection | 3.03 us |
| Luminance | Brightness update | 72 ns |
ZAP wire protocol (measured, bench/):
| Configuration | Throughput |
|---|---|
| Single connection | 114K TPS |
| 20 parallel connections | 376K TPS |
| 50 conns + batch 1000 | 20.26M TPS |
Testing
GOWORK=off go test ./...
GOWORK=off go test -bench=. ./bench/
Security Model
- Pre-quantum: Attacker must corrupt >= 1/3 stake to fork
- Q-day (BLS broken): Lattice certificates prevent unsafe finalization
- Post-quantum: Security rests on Module-LWE (Pulsar) + Module-LWE/SIS (ML-DSA)
License
BSD 3-Clause. See LICENSE.