Cross-Chain Replay Protection Test Tool

WHAT IT DOES

This tool tests cross-chain replay protection mechanisms by analyzing on-chain nonce/sequence tracking, message hash verification, and replay prevention patterns. It performs a comprehensive suite of read-only checks against a bridge contract to verify that it correctly implements replay protection through nonce/sequence tracking, message hash storage, or both. The tool checks for contract deployment verification, wallet connectivity, nonce/sequence tracking implementation, message hash tracking, chain ID inclusion, expiration timeouts, and replay attack simulation. Results are presented as a detailed test report with pass/fail/warn statuses for each test, along with mechanism-specific recommendations. This is essential for developers building cross-chain bridges, auditors verifying replay protection, and teams ensuring message delivery security.

HOW TO USE

Connect your wallet (read-only, no transaction required) and select the target network. Enter the bridge name and contract address, select the replay protection mechanism type (Nonce-based, Hash-based, or Both), and set the lookback blocks for replay analysis. Click "test replay protection" and the tool will verify the bridge contract, analyze its bytecode and ABI for replay protection patterns, check wallet connectivity, and run a comprehensive test suite tailored to the selected mechanism type. Results display a summary with pass/fail/warn counts and an overall status, detailed test cards showing each test's outcome with supporting data, and a table of all tests. Use the report to identify replay protection gaps, verify mechanism correctness, and ensure your bridge's message security is robust against replay attacks.

TECHNICAL MECHANISM

The analyzer uses ethers.js v5.7.2 to perform a multi-stage replay protection analysis. First, it calls eth_getCode to verify the bridge contract is deployed and uses block explorer APIs to fetch verification status and source code. The tool then reads the current wallet state via BGWallet for context. It analyzes the contract bytecode and ABI to detect replay protection patterns—looking for nonce tracking functions (incrementing sequence numbers, nonce validation, nonce state storage), message hash tracking (processed message mappings, hash uniqueness verification), chain ID inclusion (chain-specific validation to prevent cross-chain replays), and expiration timeouts (deadline checks for message validity). The tool also scans historical logs using eth_getLogs across the specified block range to identify nonce increments, message processing events, and replay attempt patterns. Each test in the suite evaluates a specific aspect of replay protection: contract deployment, wallet connectivity, nonce/sequence tracking (for nonce-based mechanisms), nonce gap detection (for nonce-based), message hash tracking (for hash-based mechanisms), hash collision prevention (for hash-based), chain ID inclusion, expiration timeouts, and replay attack simulation (whether the contract would reject a replayed message). Results are compiled into a structured report with detailed diagnostic information and mechanism-specific recommendations based on the selected protection type.

WHAT IT CANNOT SEE

This tool cannot actually replay messages or test replay attacks—it performs analysis of replay protection mechanisms only. It cannot access messages that have not been submitted on-chain or are pending delivery. The tool is limited by the RPC provider's rate limits and block range availability for historical log queries. It cannot verify message authenticity without access to external chain state or proof data. The analysis relies on the accuracy and completeness of contract verification and replay protection data; unverified bridges or incomplete ABIs may produce incomplete results. It cannot analyze bridges that are not verified or have opaque replay protection implementation where the mechanism is not clearly distinguishable. The tool cannot test replay protection for bridges that use off-chain or external state not reflected on-chain. It is limited to the specific bridge contracts and replay protection mechanisms that are accessible via RPC. It cannot guarantee replay protection without manual verification and attack testing across all target chains, especially for edge cases or bridge-specific features that are not captured in the bytecode analysis.

PLEASE NOTE

This is a read‑only analytics tool—it never submits transactions or replays messages. It is designed for EVM‑compatible chains and works best with verified bridge contracts. The replay protection test results are for informational and audit purposes only and should not be considered a comprehensive security audit. Always manually verify replay protection mechanisms and perform actual attack testing before relying on bridge security. The tool's pattern detection is heuristic and may miss custom replay protection implementations or bridge-specific features. Select the correct mechanism type for accurate test results.