Exchange Integration

Boba Network docs for Exchanges looking to integrate deposits and withdrawals with Boba Network

Although Boba Network is an L2 (and therefore fundamentally connected to Ethereum), it's also a separate blockchain. App developers commonly need to move data and assets between Boba Network and Ethereum. We call the process of moving data and assets between the two networks "bridging".

Sending tokens between L1 and L2

For the most common usecase, moving tokens around, we provide the Standard Token Bridge. The Standard Token Bridge is a simple smart contract with all the functionality you need to move tokens between Boba Network and Ethereum . Technical details may be found in the Optimism documentation.

The standard bridge functionality provides a method for an ERC20 token to be deposited and locked on L1 in exchange of the same amount of an equivalent token on L2. This process is known as "bridging a token", e.g. depositing 100 BOBA on L1 in exchange for 100 BOBA on L2 and also the reverse - withdrawing 100 BOBA on L2 in exchange for the same amount on L1. In addition to bridging tokens the standard bridge is also used for ETH.

The Standard Bridge is composed of two main contracts the L1StandardBridge (opens new window)(for Layer 1) and the L2StandardBridge (opens new window)(for Layer 2).

Here we'll go over the basics of using this bridge to move ERC20 and ETH assets between Layer 1 and Layer 2.

Deposits

Note: We currently block smart contract wallets from calling the depositETH and depositERC20 functions for security reasons. If you want to deposit not using an EOA accounts and you know what are doing, you can use depositETHTo and depositERC20To functions instead.

Deposit ERC20s

ERC20 deposits into L2 can be triggered via the depositERC20 and depositERC20To functions on the L1StandardBridge (opens new window). You must approve the Standard Token Bridge to use the amount of tokens that you want to deposit or the deposit will fail.

const PRIVATE_KEY, L1_NODE_WEB3_URL, PROXY_L1_STANDARD_BRIDGE_ADDRESS

const L1Provider = new ethers.providers.StaticJsonRpcProvider(L1_NODE_WEB3_URL)
const L1Wallet = new ethers.Wallet(PRIVATE_KEY).connect(L1Provider)

const Proxy__L1StandardBridge = new ethers.Contract(
  PROXY_L1_STANDARD_BRIDGE_ADDRESS,
  L1StandardBridgeABI,
  L1Wallet
)

// Approve amounts
const approveTx = await L1ERC20Contract.approve(Proxy__L1StandardBridge.address, depositAmount)
await approveTx.wait()

// Deposit ERC20
const depositTx = await Proxy__L1StandardBridge.depositERC20(
  l1TokenAddress,
  l2TokenAddress,
  depositAmount,
  1300000, // l2 gas limit
  ethers.utils.formatBytes32String(new Date().getTime().toString()) // byte data
)
await depositTx.wait()

// Deposit ERC20 to another l2 wallet
const depositToTx = await Proxy__L1StandardBridge.depositERC20To(
  l1TokenAddress,
  l2TokenAddress,
  TargetAddress, // l2 target address
  depositAmount,
  1300000, // l2 gas limit
  ethers.utils.formatBytes32String(new Date().getTime().toString()) // byte data
)
await depositToTx.wait()

Deposit ETH

ETH deposits into L2 can be triggered via the depositETH and depositETHTo functions on the L1StandardBridge (opens new window)). ETH deposits can alternatively be triggered by sending ETH directly to the L1StandardBridge. Once your deposit is detected and finalized on Boba Network, your account will be funded with the corresponding amount of ETH on L2.

const PRIVATE_KEY, L1_NODE_WEB3_URL, PROXY_L1_STANDARD_BRIDGE_ADDRESS

const L1Provider = new ethers.providers.StaticJsonRpcProvider(L1_NODE_WEB3_URL)
const L1Wallet = new ethers.Wallet(PRIVATE_KEY).connect(L1Provider)

const Proxy__L1StandardBridge = new ethers.Contract(
  PROXY_L1_STANDARD_BRIDGE_ADDRESS,
  L1StandardBridgeABI,
  L1Wallet
)

// Deposit ETH
const depositTx = await Proxy__L1StandardBridge.depositETH(
  1300000, // l2 gas limit
  ethers.utils.formatBytes32String(new Date().getTime().toString()), // byte data
  {value: ETHAmount}
)
await depositTx.wait()

// Deposit ETH to another l2 wallet
const depositToTx = await Proxy__L1StandardBridge.depositETHTo(
  TargetAddress, // l2 target address
  depositAmount,
  1300000, // l2 gas limit
  ethers.utils.formatBytes32String(new Date().getTime().toString()), // byte data
  {value: ETHAmount}
)
await depositToTx.wait()

Withdrawals

Withdraw tokens (ERC20s and ETH)

ERC20 withdrawals can be triggered via the withdraw or withdrawTo functions on the L2StandardBridge

const PRIVATE_KEY, L2_NODE_WEB3_URL, PROXY_L2_STANDARD_BRIDGE_ADDRESS

const L2Provider = new ethers.providers.StaticJsonRpcProvider(L2_NODE_WEB3_URL)
const L2Wallet = new ethers.Wallet(PRIVATE_KEY).connect(L2Provider)

const Proxy__L2StandardBridge = new ethers.Contract(
  PROXY_L2_STANDARD_BRIDGE_ADDRESS,
  L2StandardBridgeABI,
  L2Wallet
)

// Withdraw ETH
// ETH address is 0x4200000000000000000000000000000000000006 on L2
const depositTx = await Proxy__L2StandardBridge.withdraw(
  '0x4200000000000000000000000000000000000006', // l2 token address
  ETHAmount,
  9999999, // l1 gas limit
  ethers.utils.formatBytes32String(new Date().getTime().toString()), // byte data
  {value: ETHAmount}
)
await depositTx.wait()

// Withdraw ETH to another l1 wallet
// ETH address is 0x4200000000000000000000000000000000000006 on L2
const depositToTx = await Proxy__L2StandardBridge.withdrawTo(
  '0x4200000000000000000000000000000000000006', // l2 token address
  TargetAddress, // l1 target address
  ETHAmount,
  9999999, // l1 gas limit
  ethers.utils.formatBytes32String(new Date().getTime().toString()), // byte data
  {value: ETHAmount}
)
await depositToTx.wait()

// Approve amounts
const approveTx = await L2ERC20Contract.approve(Proxy__L2StandardBridge.address, exitAmount)
await approveTx.wait()

// Withdraw ERC20
const depositTx = await Proxy__L2StandardBridge.withdraw(
  l2TokenAddress // l2 token address
  exitAmount,
  9999999, // l1 gas limit
  ethers.utils.formatBytes32String(new Date().getTime().toString()), // byte data
)
await depositTx.wait()

// Withdraw ERC20 to another l1 wallet
const depositToTx = await Proxy__L2StandardBridge.withdrawTo(
  l2TokenAddress, // l2 token address
  TargetAddress, // l1 target address
  exitAmount,
  9999999, // l1 gas limit
  ethers.utils.formatBytes32String(new Date().getTime().toString()), // byte data
)
await depositToTx.wait()

Withdrawals must be claimed on the L1 network in a two-step process, firstly by proving the L2 withdrawal transaction and later by finalizing the transaction. There is a mandatory interval (7 days on mainnet) which must pass before a withdrawal may be finalized. This time interval provides an opportunity to challenge the validity of the transaction, a defining characteristic of Optimistic Rollups. Details may be found on the Optimism page describing Withdrawal Flow.

The Boba token list

The Standard bridge allows a one-to-many mapping between L1 and L2 tokens, meaning that there can be many Boba implementations of an L1 token. However there is always a one-to-one mapping between L1 and L2 tokens in the Boba token list.

Network	URL
Mainnet	[Mainnet Boba Token List](token-addresses.md#Ethereum <> BOBA L2)
Sepolia	[Sepolia Boba Token List](token-addresses.md#Sepolia <> BOBA L2)

Links

Mainnet

Contract Name	Contract Address
Proxy__L1StandardBridge	0xdc1664458d2f0B6090bEa60A8793A4E66c2F1c00
Proxy__L2StandardBridge	0x4200000000000000000000000000000000000010

Sepolia

Contract Name	Contract Address
Proxy__L1StandardBridge	0x244d7b81EE3949788Da5F1178D911e83bA24E157
Proxy__L2StandardBridge	0x4200000000000000000000000000000000000010