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LayerZero

Wrapped Asset Bridge

Wrapped asset bridge allows bridging ERC20 tokens and native gas tokens (e.g. ETH) from existing EVM chains (e.g. Ethereum, Avalanche, BSC, etc.) to subnets or brand new EVM chains where those assets do not exist natively. It supports mapping the same wrapped token to multiple tokens on other chains. E.g. moving native USDC from Ethereum or Avalanche to NewChainX will result in the same wrapped asset on NewChainX.


badge-warning
The bridge is not intended for bridging between existing L1 EVM chains (e.g. between Ethereum and Avalanche)


Getting Started

Setup

  • Clone the repository
  • run yarn

Test

yarn test

Run the full suite of unit tests.

Coverage

yarn coverage

Get the coverage report.


Deployment and configuration

  1. Deploy OriginalTokenBridge.sol on existing EVM chains.
  2. Deploy WrappedTokenBridge.sol on the new EVM chain.
  3. Call setTrustedRemoteAddress in WrappedTokenBridge contract and in each OriginalTokenBridge contract.
  4. For each token you want to bridge (e.g., USDC, WETH, etc), deploy WrappedERC20 contract on the new EVM chain. Make sure to set decimals in the WrappedERC20 to the number of decimals used in the original token you want to bridge (e.g., 6 decimals for USDC, 18 decimals for WETH). If you want to add an additional functionality to the wrapped token, inherit it from WrappedERC20 and add a custom logic to the derived contract.
  5. For each token you want to bridge, call registerToken(address token, uint8 sharedDecimals) function in OriginalTokenBridge and registerToken(address localToken, uint16 remoteChainId, address remoteToken) function in WrappedTokenBridge. Each wrapped token can be mapped to multiple original tokens on different chains (e.g. USDC on the new chain is mapped to USDC on Ethereum and USDC on Avalanche).

Bridging from a native asset EVM chain to a new EVM chain

  1. Call estimateBridgeFee(bool useZro, bytes calldata adapterParams) in OriginalTokenBridge contract.
  2. Call bridge(address token, uint amount, address to, LzLib.CallParams calldata callParams, bytes memory adapterParams) in OriginalTokenBridge contract to bridge ERC20 tokens passing nativeFee obtained earlier as a value. This will lock ERC20 tokens in OriginalTokenBridge contract and send a LayerZero message to the WrappedTokenBridge on another chain to mint wrapped tokens. To bridge ETH use bridgeETH(uint amount, address to, LzLib.CallParams calldata callParams, bytes memory adapterParams) function and pass a sum of nativeFee and amount as a value.

Bridging from a new EVM chain to a native asset EVM

  1. Call estimateBridgeFee(uint16 remoteChainId, bool useZro, bytes calldata adapterParams) in WrappedTokenBridge.
  2. Call (address localToken, uint16 remoteChainId, uint amount, address to, bool unwrapWeth, LzLib.CallParams calldata callParams, bytes memory adapterParams) supplying nativeFee obtained earlier as a value. This will burn wrapped tokens and send a LayerZero message to OriginalTokenBridge contract on another chain to unlock original tokens.