Paymaster Validation Logic Tester

WHAT IT DOES

Paymaster Validation Logic Tester provides comprehensive testing for ERC-4337 paymaster validation logic, helping developers ensure that paymaster contracts correctly validate UserOperations before sponsoring gas costs. It retrieves on-chain EntryPoint contract bytecode via eth_getCode and fetches verified source code and ABI from block explorer APIs. The tool analyzes paymaster contract bytecode and source code, examines UserOperation data with paymasterAndData fields, and validates account factory and wallet contract interactions. It runs a suite of validation checks including paymaster address format validation, paymaster deposit balance verification, paymaster validation logic execution, paymasterAndData format validation, paymaster signature verification, and paymaster gas cost verification. The output includes a validation status (Valid, Invalid, or Partial), count of paymaster checks passed, gas estimate (including paymaster overhead), a detailed check matrix showing each validation check's result, and actionable recommendations for resolving issues—such as invalid paymaster addresses, insufficient paymaster deposits, malformed paymasterAndData, incorrect paymaster signatures, or paymaster gas estimation errors. This enables AA wallet developers, bundler operators, and paymaster implementers to verify that paymaster validation logic is correctly implemented and secure before deploying to production.

HOW TO USE

Connect your BGWallet to the target EVM chain. Paste the address of the ERC-4337 EntryPoint contract you wish to use. Provide the paymaster contract address you want to test and a UserOperation JSON object containing the paymasterAndData field with the paymaster-specific data. Optionally supply a GitHub repository URL to pull paymaster implementation details and validation specifications for additional context. The tool fetches the EntryPoint and paymaster contract bytecode, analyzes the provided UserOperation, and runs a comprehensive validation suite. Review the validation status, checks passed count, gas estimate, check matrix, and recommendations. Use the results to verify that your paymaster correctly validates UserOperations and that it is ready for production use.

PAYMASTER VALIDATION AND SECURITY ANALYSIS ENGINE

The real technical mechanism is the paymaster validation and security analysis engine that combines EntryPoint bytecode analysis with paymaster-specific validation semantics. The tool first analyzes the EntryPoint contract's bytecode to understand the paymaster validation flow—specifically how the EntryPoint calls validatePaymasterUserOp on the paymaster contract during handleOps execution. It then retrieves the paymaster contract's bytecode and disassembles it to locate the validatePaymasterUserOp function, analyzing its logic to understand the validation rules it enforces. The engine validates that the paymaster contract implements the correct ERC-4337 interface and that the validatePaymasterUserOp function returns the expected values (validated and context). It also checks that the paymaster has sufficient deposit in the EntryPoint to cover the gas costs and that the paymasterAndData field is correctly formatted. The signature verification ensures that the paymaster's signature is valid and matches the expected signer. The gas verification step estimates the gas cost of the paymaster validation and post-operation logic, ensuring that the paymaster has enough funds to cover the operation. The security analysis identifies potential vulnerabilities in paymaster logic—such as reentrancy risks, insufficient access controls, or incorrect validation of UserOperation fields. This approach provides developers with a comprehensive, automated way to test paymaster validation logic, catching issues that would otherwise only surface during live operations and preventing gas sponsorship failures or security breaches.

WHAT IT CANNOT SEE

This tool cannot generate a complete paymaster validation test without access to EntryPoint or paymaster contract bytecode. It is limited by your RPC provider's rate limits for data retrieval, which may delay analysis on congested networks. It cannot determine if paymaster validation correctly processes UserOperations without executing the validation logic—static analysis provides insights but does not replace full execution. The detection relies on the completeness of the ABI and source code verification; unverified contracts or incomplete verification data will produce incomplete or inaccurate results. Detection is based on bytecode pattern matching and may miss indirect or obfuscated paymaster logic, such as validation logic hidden in libraries or via delegate calls. The tool cannot assess runtime behavior or security implications of paymaster validation, such as how the paymaster reacts to malicious UserOperations or edge-case inputs. It may produce false positives for data that appears similar to paymaster data but is used for other purposes. The tool does not execute the contract to validate paymaster logic, so it cannot confirm that the paymaster correctly handles all possible UserOperation variations. It cannot account for network-specific paymaster implementation differences or future upgrades—different chains may have different EntryPoint implementations or modifications to ERC-4337. Paymaster validation logic may vary across implementations and change over time as standards evolve.

PLEASE NOTE

This tool works exclusively with EVM-compatible chains that support ERC-4337 account abstraction. It requires active internet connectivity to access block explorer APIs and RPC endpoints. Some block explorers may require API keys for high-volume bytecode retrieval. The tool is read-only and does not execute any transactions—it only produces validation assessments. Paymaster validation is critical to AA security; always verify validation results against official ERC-4337 specifications and test on testnet before mainnet deployment. Different paymaster implementations may have different validation requirements and security considerations.