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Step 4: Ensuring Security

Integrating with external data and calls requires additional security measures.

1. Protect Against Reentrancy Attacks​

If your function interacts with external contracts or transfers ETH/tokens, use the nonReentrant modifier (from OpenZeppelin ReentrancyGuard).

import "@openzeppelin/contracts/security/ReentrancyGuard.sol";

contract YourContract is ReentrancyGuard {
    function someRestrictedFunction(address _to, bytes calldata _purefidata) external nonReentrant {
        verifier.validatePayload(_purefidata);
        // Logic involving transfers
    }
}

2. Validate Input Data​

Add checks for minimum values or parameter correctness to prevent spam or errors.

function someRestrictedFunction(address _to, bytes calldata _purefidata) external payable nonReentrant {
    require(msg.value >= 0.01 ether, "Minimum 0.01 ETH required");
    verifier.validatePayload(_purefidata);
    // Logic
}

3. Restrict Access​

Use modifiers to limit access to critical functions (e.g., onlyOwner).