Overview
BOB Gateway enables users to interact with DeFi protocols using a single Bitcoin transaction. There are three integration approaches:
Custom Strategy
Full control with smart contracts
Multicall
No deployment needed
Cross-Chain
Execute on destination chains
Which Approach Should I Choose?
Custom Strategy - For Complex Logic
Choose this when you need:
- Complex multi-step operations
- Gas optimization
- Custom events and logging
- Full control over execution flow
- State management in your contract
Multicall - For Quick Integration
Choose this when you want to:
- Integrate with existing contracts on BOB
- Avoid deploying new contracts
- Implement simple approve + deposit patterns
- Get started quickly
Cross-Chain - For LayerZero Bridges
Choose this for:
- Bridging to Ethereum, Base, or other LayerZero chains
- Executing actions on destination chain after bridge
- Depositing into lending protocols on destination
- Multi-step operations post-bridge
Option 1: Custom Strategy Contract
Deploy a smart contract that implements the Gateway strategy interface for full control.
Strategy Interface
interface IStrategy {
function handleGatewayMessage(
IERC20 tokenSent, // Wrapped BTC token (WBTC, tBTC, etc.)
uint256 amountIn, // Amount received
address recipient, // User's EVM address
bytes memory message // Optional parameters
) external;
}
Complete Example: Convert to SolvBTC
import {IERC20} from "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import {SafeERC20} from "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
interface ISolvBTCRouter {
function deposit(
address targetToken_,
address currency_,
uint256 currencyAmount_,
uint256 minimumTargetTokenAmount_,
uint64 expireTime_
) external returns (uint256);
}
contract SolvBTCStrategy {
using SafeERC20 for IERC20;
ISolvBTCRouter public immutable solvBTCRouter;
IERC20 public immutable solvBTC;
constructor(address _solvBTCRouter, address _solvBTC) {
solvBTCRouter = ISolvBTCRouter(_solvBTCRouter);
solvBTC = IERC20(_solvBTC);
}
function handleGatewayMessage(
IERC20 tokenSent,
uint256 amountIn,
address recipient,
bytes memory message
) external {
// Transfer wrapped BTC from Gateway
tokenSent.safeTransferFrom(msg.sender, address(this), amountIn);
// Decode minimum output from message (optional)
uint256 minOutput = message.length > 0
? abi.decode(message, (uint256))
: 0;
// Approve SolvBTC router
tokenSent.safeIncreaseAllowance(address(solvBTCRouter), amountIn);
// Convert to SolvBTC
uint256 solvBTCAmount = solvBTCRouter.deposit(
address(solvBTC),
address(tokenSent),
amountIn,
minOutput,
uint64(block.timestamp + 1)
);
// Send SolvBTC to user
solvBTC.safeTransfer(recipient, solvBTCAmount);
}
}
Using Your Custom Strategy
import { GatewaySDK, parseBtc } from '@gobob/bob-sdk';
const gatewaySDK = new GatewaySDK(bob.id);
// Encode minimum output parameter
const minOutput = parseUnits("0.099", 8); // Minimum 0.099 BTC worth
const message = encodeAbiParameters(
[{ type: 'uint256' }],
[minOutput]
);
const quote = await gatewaySDK.getQuote({
fromChain: 'bitcoin',
fromToken: 'BTC',
toChain: 'bob',
toToken: '0xYourStrategyAddress', // Your deployed strategy
fromUserAddress: 'bc1q...',
toUserAddress: '0x...', // Receives the SolvBTC
amount: parseBtc("0.1"),
strategyMessage: message, // Optional parameters
});
Option 2: Multicall Strategy
Execute multiple contract calls without deploying custom contracts.
Basic Approve + Deposit Pattern
import {
encodeFunctionData,
parseAbi,
encodeAbiParameters,
parseAbiParameters,
Address
} from 'viem';
import { GatewaySDK, parseBtc } from '@gobob/bob-sdk';
const WBTC_ADDRESS = '0x03C7054BCB39f7b2e5B2c7AcB37583e32D70Cfa3'; // BOB mainnet
const PROTOCOL_ADDRESS = '0xYourProtocolAddress';
function generateMulticallMessage(
userAddress: Address,
depositAmount: bigint
) {
// Step 1: Approve protocol to spend WBTC
const approveCall = encodeFunctionData({
abi: parseAbi(['function approve(address spender, uint256 value)']),
functionName: 'approve',
args: [PROTOCOL_ADDRESS, depositAmount],
});
// Step 2: Deposit into protocol
const depositCall = encodeFunctionData({
abi: parseAbi(['function deposit(address asset, uint256 amount, address onBehalfOf)']),
functionName: 'deposit',
args: [WBTC_ADDRESS, depositAmount, userAddress],
});
// Encode as multicall message
return encodeAbiParameters(
parseAbiParameters('((address target, bytes callData, uint256 value)[], address fallbackRecipient)'),
[
[
[
{ target: WBTC_ADDRESS, callData: approveCall, value: 0n },
{ target: PROTOCOL_ADDRESS, callData: depositCall, value: 0n },
],
userAddress, // Fallback recipient if execution fails
],
]
);
}
// Get quote with multicall
const depositAmount = parseBtc("0.1");
const multicallMessage = generateMulticallMessage(userAddress, depositAmount);
const quote = await gatewaySDK.getQuote({
fromChain: 'bitcoin',
fromToken: 'BTC',
toChain: 'bob',
toToken: 'wBTC',
fromUserAddress: 'bc1q...',
toUserAddress: userAddress,
amount: depositAmount,
strategyMessage: multicallMessage,
});
Advanced: Multi-Protocol Interaction
function generateComplexMulticall(user: Address, amount: bigint) {
const calls = [
// 1. Approve DEX router
{
target: WBTC_ADDRESS,
callData: encodeFunctionData({
abi: erc20Abi,
functionName: 'approve',
args: [DEX_ROUTER, amount / 2n],
}),
value: 0n,
},
// 2. Swap half to another token
{
target: DEX_ROUTER,
callData: encodeFunctionData({
abi: parseAbi(['function swapExactTokensForTokens(...)']),
functionName: 'swapExactTokensForTokens',
args: [/* swap params */],
}),
value: 0n,
},
// 3. Add liquidity
{
target: DEX_ROUTER,
callData: encodeFunctionData({
abi: parseAbi(['function addLiquidity(...)']),
functionName: 'addLiquidity',
args: [/* liquidity params */],
}),
value: 0n,
},
];
return encodeAbiParameters(
parseAbiParameters('((address target, bytes callData, uint256 value)[], address fallbackRecipient)'),
[[calls, user]]
);
}
Option 3: Cross-Chain Destination Calls
Coming Soon - This feature is currently under development and will be available soon.
Next Steps
