shutter-bridge

This repo locks underlying $SHU tokens on Ethereum and mints synthetic tokens in Optimsm Chain or burn synthetic to unlock $SHU on the oposite direction.

What's inside?

• Optimism Portal
• Proposal to deploy SHU on Optimism
• Github Issue
• Shutter Token on Ethereum Sepolia
• Shutter Token on Optimism Sepolia
• Shutter Token on Ethereum
• Shutter Token on Optimism

Getting Started

Start by installing the dependencies:

$ yarn

Then set the environment variables by copying the .env.example file and removing the .example extension, then fill in the values:

• RPC URLs: You can try public RPCs but they might not work properly. Try using Alchemy or Infura for this.
• PRIVATE KEY: The private key of the account that will be used to deploy the contracts.
• ETHERSCAN KEY: Optional but recommended. Used to verify the contracts on Etherscan. You will only need once in case you deploy your own SHU token.
• SHUTTER TOKEN ADDRESS: The address of the Shutter Token contract deployed on each chain.

NOTE: Repair that you have testnet/mainnet tokens and one of them will be commented because the scripts use the same file name.

Deploying the contracts

You can choose between deploying a new contract or use the existing contract that were previsouly deployed by Blockful. The contract addresses were already set in the .env.sample file. you can directly mint new tokens by calling the mint script.

Deploy your own Shutter Token on Sepolia network by calling:

$ yarn deploy:l1 --network sepolia

The contract should be deployed on Sepolia. After deploying the Shutter Token, you need to set the SHUTTER_TOKEN_CONTRACT in the .env file.

Optionally, you can verify the contract on Etherscan with:

$ npx hardhat verify --network sepolia <CONTRACT_ADDRESS> <OWNER_ADDRESS>

For the deployment on the Optimism network, you need to call:

NOTE: Can only be used after the Sepolia contract has been deployed and .env filled.

$ yarn deploy:l2 --network op_sepolia

Fetch the contract address logged on the terminal then change the value for the BRIDGED_SHUTTER_TOKEN_CONTRACT in the .env file.

Bridging tokens from Ethereum to Optimism

Before bridging the tokens:

• Make sure that you have both token contracts correctly set in the .env file. The Shutter Token on Ethereum and the bridged Shutter Token on Optimism.
• Make sure that you have the right l1StandardBridge address uncommented in the bridgeToL2.ts script. The address should be the one that corresponds to the network you are bridging from.
• We already wrote the addresses in the .env file for both testnet and mainnet in advance. Make sure the right one is uncommented.

You can bridge tokens from L1 to L2 by calling the bridgeToL2.ts script. Your tokens will be approved from being transferred by the bridge, then your tokens will be locked on one side and minted on the other side.

$ yarn bridge:to:l2 --network sepolia

NOTE: You will enconter the following error/warning in the block explorer:

• "Although one or more Error Occurred [execution reverted] Contract Execution Completed"

This will happen 100% of the times because the $SHU token doesn't implement ERC165 and the OP Portal tests for this interfaceId. This is merely a visual issue but the bridge will work as expected.

Bridging tokens from Optimism to Ethereum

NOTE FROM OP: The final step to withdrawing tokens from L2 to L1 is to relay the withdrawal on L1. This can only happen after the fault proof period has elapsed. On OP Mainnet, this takes 7 days. We're currently testing fault proofs on OP Sepolia, so withdrawal times reflect Mainnet times.

Before bridging the tokens:

• Make sure that you have both token contracts correctly set in the .env file. The Shutter Token on Ethereum and the bridged Shutter Token on Optimism.
• Make sure that you are on the desired set of networks between testnet and mainnet. You can switch them by commenting and uncommenting in the .env file and the respective scripts.
• In the proveWithdraw.ts and withdrawToL1.ts scripts at L25 and L26, make sure that the l1ChainId and l2ChainId represents your desired networks.

There is two ways of proving the withdrawal:

• Using a hybrid approach
• Using the OP SDK

Using a hybrid approach

Before bridging the tokens, make sure that you have a valid bridged ERC20 set in BRIDGED_SHUTTER_TOKEN_CONTRACT in the .env file.

You can bridge tokens by calling the bridgeToL2.ts script directly in the ERC677 token contract. This will burn the tokens on one side and unlock them on the other side.

$ yarn bridge:to:l1 --network op_sepolia

Get the resulting transaction hash on the terminal or any other tx hash that represented the burn of the synthetic assets on OP and place on the withdrawHash variable inside the proveWithdraw.ts script then run with:

$ yarn prove

NOTE: Any EOA can prove the withdraw for another address by providing the txHash of the withdraw operation

Using the OP SDK

You can use the OP SDK to prove the withdrawal. The SDK will automatically withdraw the tokens and prove the withdrawal.

$ yarn withdraw:to:l1

NOTE: The owner of the tokens must be the prover, hence you need to provide a private key, therefore you can only withdraw as an EOA

Minting more tokens on L1

You can mint more tokens on L1 Ethereum or Sepolia by calling the mint script. But you cant mint more tokens on the OP network. The tokens are minted on the Ethereum network and then bridged to the OP network. You will receive 1000e18 tokens per mint.

$ yarn mint --network sepolia

License

This project is licensed under MIT.