Lux Docs

The Lux Bridge is a cross-chain asset transfer system built on MPC threshold signing.

Components

Component	Technology	Purpose
Bridge UI	Next.js	User-facing web interface
Bridge API	Node.js	Transfer management and chain monitoring
MPC Cluster	Go (mpcd)	Threshold key generation and signing
PostgreSQL	PostgreSQL	Transfer state and history
Valkey	Redis-compatible	Cache and rate limiting

System Architecture

User Browser
  -> Bridge UI (bridge.lux.network)
    -> Bridge API (bridge-api.lux.network:3000)
      -> PostgreSQL (transfer state)
      -> Valkey (cache)
      -> MPC Cluster (3 nodes, consensus mode)
        -> Source chain RPC (verify deposits)
        -> Destination chain RPC (submit withdrawals)

Transfer Flow

Deposit (External to Lux)

User locks tokens in bridge contract on source chain
Bridge API monitors source chain for deposit events
After required confirmations, API creates signing request
MPC nodes produce threshold signature for mint transaction
Bridge API broadcasts mint transaction on destination chain

Withdrawal (Lux to External)

User burns wrapped tokens on Lux chain
Bridge API monitors Lux chain for burn events
After confirmation, API creates signing request
MPC nodes produce threshold signature for release transaction
Bridge API broadcasts release transaction on destination chain

Kubernetes Deployment

lux-bridge namespace:
  bridge-ui:3000      -> bridge.lux.network
  bridge-api:3000     -> bridge-api.lux.network
  bridge-postgres:5432
  bridge-valkey:6379
  mpc-node-{0,1,2}    -> consensus transport

MPC Key Management

Keys are generated once via distributed key generation (DKG)
Each MPC node holds a key share, never the full key
Bridge contract addresses are derived from MPC public keys
Key rotation uses reshare protocol (addresses unchanged)

Failover

MPC: 2-of-3 threshold allows 1 node failure
Bridge API: Multiple replicas behind load balancer
PostgreSQL: Streaming replication
Valkey: Sentinel for automatic failover

Architecture

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