LP-0091Finalbridgetokenlrc20berc20mint-burn

LP-091: LRC20B Bridge Token Standard

Abstract

Defines LRC20B (Lux Regulated Cross-Chain 20 Bridged), the standard for bridged tokens on Lux Network. When an asset (ETH, BTC, USDC, etc.) is locked on its native chain, a corresponding LRC20B token is minted on Lux. The bridge operator (MPC multisig, LP-019) controls minting. 67+ tokens are bridged at launch covering major L1 assets, stablecoins, and DeFi tokens.

Specification

Contract


contract LRC20B is ERC20, AccessControl {
    bytes32 public constant BRIDGE_ROLE = keccak256("BRIDGE_ROLE");

    function bridgeMint(address to, uint256 amount) external onlyRole(BRIDGE_ROLE);
    function bridgeBurn(address from, uint256 amount) external onlyRole(BRIDGE_ROLE);
    function originChain() external view returns (uint256);
    function originToken() external view returns (address);
}

Properties

| Property | Description |

|----------|-------------|

| BRIDGE_ROLE | MPC multisig (LP-019). Only entity that can mint/burn. |

| originChain | Chain ID of the native token (e.g., 1 for Ethereum) |

| originToken | Address on the origin chain (0x0 for native assets) |

| Decimals | Match origin token decimals |

Token Registry

Selected bridged tokens (67+ total):

| Symbol | Origin | Origin Chain |

|--------|--------|-------------|

| WETH.b | WETH | Ethereum |

| WBTC.b | WBTC | Ethereum |

| USDC.b | USDC | Ethereum |

| USDT.b | USDT | Ethereum |

| DAI.b | DAI | Ethereum |

| SOL.b | SOL | Solana |

| BNB.b | BNB | BNB Chain |

| MATIC.b | MATIC | Polygon |

| ARB.b | ARB | Arbitrum |

The .b suffix denotes a bridged representation. The full registry is maintained in the BridgeRegistry contract.

Mint/Burn Flow


Lock (external chain):
  User locks 1 ETH on Ethereum bridge contract
  MPC multisig observes lock, waits for finality
  MPC calls bridgeMint(user, 1e18) on Lux -> user receives 1 WETH.b

Burn (Lux -> external):
  User calls bridge.burn(1 WETH.b)
  MPC observes burn, waits for finality
  MPC releases 1 ETH on Ethereum to user

Cross-L1 / L2 Teleport

LRC20B tokens can move between Lux L1 / L2 chains (per LP-018) via Warp messaging without additional lock/mint cycles. The token contract on each chain recognizes the Warp-relayed transfer.

Security Considerations

1. BRIDGE_ROLE is held by the MPC multisig (3-of-5 minimum). No single key can mint bridged tokens.

2. Minting without a corresponding lock on the origin chain is detectable via the bridge audit log.

3. The BridgeRegistry is append-only. Removing a token requires governance approval.

4. Bridged tokens are always backed 1:1. The bridge contract on the origin chain holds the exact backing.

Reference

| Resource | Location |

|----------|----------|

| LRC20B contract | github.com/luxfi/standard/contracts/bridge/LRC20B.sol |

| BridgeRegistry | github.com/luxfi/standard/contracts/bridge/BridgeRegistry.sol |

| MPC signing | LP-019 |

Copyright

Licensed under the MIT License.