LP-3023: LRC-20 Bridgable Extension

Abstract

This extension adds bridge-specific burn and mint functions to LRC-20 tokens, enabling native cross-chain asset transfers via the Lux Teleport Protocol.

Motivation

Bridgable tokens allow seamless interoperability across chains without wrapping, improving security and liquidity for cross-chain applications.

Specification

interface IERC20Bridgable is IERC20Mintable, IERC20Burnable {
    /**
     * @dev Burns `_amount` tokens from caller for cross-chain bridge.
     */
    function bridgeBurn(address to, uint256 amount) external;

    /**
     * @dev Mints `_amount` bridged tokens to `_from` upon cross-chain arrival.
     */
    function bridgeMint(address from, uint256 amount) external;
}

Rationale

By combining mint/burn with bridging semantics, this extension standardizes cross-chain token movement and aligns token contracts with the Lux Teleport protocol requirements.

Backwards Compatibility

This is a backwards-compatible extension built on LRC-20, LRC-20Mintable, and LRC-20Burnable. Core token functionality remains intact.

Test Cases

Standard tests should cover:

bridgeBurn and bridgeMint flows
Integration with Teleport Protocol engine
Supply consistency across burns and mints

Reference Implementation

See the IERC20Bridgable interface in the standard repository:

/standard/src/interfaces/IERC20Bridgable.sol

Implementation

LRC-20 Bridgable Token Contracts

Location: ~/work/lux/standard/src/tokens/

Core Contracts:

LRC20.sol - Base implementation
ERC20Bridgable.sol - Bridge extension
ERC20Mintable.sol - Minting capability
ERC20Burnable.sol - Burning capability

Bridge Integration (Teleport Protocol):

Location: ~/work/lux/standard/src/bridge/
TeleportMessenger.sol - Cross-chain messaging
BridgeRelay.sol - Message relay

Bridging Implementation:

// Example from ERC20Bridgable.sol
function bridgeBurn(address from, uint256 amount) external onlyBridgeRelayer {
    require(from != address(0), "Invalid address");
    _burn(from, amount);
    emit BridgeBurn(from, amount);
}

function bridgeMint(address to, uint256 amount) external onlyBridgeRelayer {
    require(to != address(0), "Invalid recipient");
    _mint(to, amount);
    emit BridgeMint(to, amount);
}

Testing:

cd ~/work/lux/standard
forge test --match-contract ERC20BridgableTest
forge coverage --match-contract ERC20Bridgable

Gas Costs

Operation	Gas Cost	Notes
bridgeBurn	~45,000	Token burn + bridge event
bridgeMint	~50,000	Token mint + bridge event
setBridgeRelayer	~20,000	Access control update

Security Considerations

Ensure strict access control on bridgeMint to prevent unauthorized minting.
Validate correct burn amounts and cross-chain message proofs.
Only bridge relayers can invoke bridgeBurn/bridgeMint.
Implement rate limiting to prevent bridge floods.
Verify message signatures from the Teleport Protocol.

LRC-20 Bridgable Extension