zeekayandHanzo Dev
6cf38d2e48
SECURITY: every wallet keyed by these rings was a 1-of-n key — any single
node's share could produce a valid signature, with no threshold protection
against single-node compromise. This affects real value: the bridge-mpc
`bridge-oracle` (LUX↔ZOO corridor signer), zoo-treasury-v1, and the
hanzo-dao wallet were all keyed at CGGMP21 polynomial degree 0.
Root cause: two disconnected "threshold" values. The --threshold flag
(c.Int("threshold")) drove only the HasSigningQuorum health gate and status
display. The keygen DEGREE was read separately from viper key
"mpc_threshold" (pkg/eventconsumer → CreateKeyGenSession → cmp.Keygen), which
nothing ever set — and mpcd never calls config.InitViperConfig, so
viper.AutomaticEnv was off and even an MPC_THRESHOLD env would not have been
read. viper.GetInt("mpc_threshold") was therefore always 0 → degree 0 →
1-of-n.
Fix: bridge the flag to the keygen degree at consensus start via
viper.Set("mpc_threshold", keygenDegreeForThreshold(threshold)). --threshold
is the number of signers required (matches HasSigningQuorum); cmp.Keygen
needs degree+1 signers, so degree = threshold-1. --threshold=3 → degree 2 →
3-of-5; --threshold=2 → degree 1 → 2-of-3. keygenDegreeForThreshold is a
named, unit-tested function so the security-critical off-by-one is explicit.
Takes effect for NEW keygens only; existing 1-of-n wallets must be re-keyed
to gain threshold security (the live bridge-oracle needs a coordinated
migration — do not re-key in place).
Co-authored-by: Hanzo Dev <[email protected]>
mpcd — MPC Daemon
mpcd is a threshold-signature daemon. It speaks ZAP wire protocol over
TLS 1.3 directly between peers — no NATS, no Consul, no PostgreSQL in the
critical path. The daemon is the same binary in every deployment shape;
the operating mode is selected entirely by flags.
Operating modes
There is exactly one start command (mpcd start) and the topology is
determined by the --peer and --threshold flags:
| Topology | Flags | Use |
|---|---|---|
| Standalone (1-of-1 self-loop) | --threshold 1 (no --peer) |
Smoke tests, dev sandbox |
| Networked t-of-n cluster | --threshold t --peer ... (n−1 peers) |
Production |
In all cases mpcd runs the consensus-embedded transport
(pkg/transport). The "consensus" here is local PoA membership over the
node's own Ed25519 identities — it is intentionally not the Lux mainnet
chain, because key shares must never leave the cluster.
Standalone (1-of-1)
mpcd start \
--node-id solo \
--listen :9999 \
--api :9800 \
--data /var/lib/mpcd \
--threshold 1
Starts mpcd with itself as the only quorum member. /healthz will report
signing_quorum: true immediately. Keygen and signing of fresh wallets
require ≥2 parties — CGGMP21 and FROST cannot produce shares with a
single party — so this mode exists only for boot-up smoke tests, e2e
harness fixtures, and verifying TLS / membership / API plumbing. For real
signing, run a multi-node cluster.
Networked (t-of-n)
# Node 0
mpcd start --node-id node0 --listen :9999 --api :9800 \
--data /data/node0 --threshold 2 \
--peer [email protected]:9999 --peer [email protected]:9999
# Node 1
mpcd start --node-id node1 --listen :9999 --api :9800 \
--data /data/node1 --threshold 2 \
--peer [email protected]:9999 --peer [email protected]:9999
# Node 2 — same pattern
The daemon expects the cluster size n = len(peers) + 1 and rejects start
when threshold > n. See pkg/transport/registry.go::HasSigningQuorum for
the quorum arithmetic.
Smoke test
go test -tags=integration ./cmd/mpcd/... -count=1 -timeout 90s
standalone_test.go builds mpcd, runs it with --threshold 1 on free
ports and a fresh data directory, polls /healthz until quorum holds,
and asserts the response shape. It does not exercise keygen — see e2e/
for that.