Invalid Signature Error Explainer

WHAT IT DOES

Invalid Signature Error Explainer takes a pending or recent permit, meta-transaction, or signature-based transaction hash and determines whether it will fail due to an invalid signature. It decodes the transaction calldata to extract the signature components (v, r, s) and the associated parameters—such as the owner/signer address, spender, amount, nonce, and deadline. It then recovers the signer address from the signature using ecrecover and compares it to the expected signer (the owner or from parameter in the transaction). The tool also checks the nonce used in the signature against the contract's current nonce for that signer (by reading the contract's nonce mapping), verifies that the deadline has not passed by comparing against the current block timestamp, and confirms that the chain ID matches the network. The output includes whether the signature is valid, the recovered signer, the expected signer, the nonce status, the deadline status, and a plain‑language explanation of what is wrong and how to fix it—such as using the correct private key, increasing the deadline, or ensuring the nonce is current.

HOW TO USE

Paste any signature-based transaction hash (e.g., a permit, approve via signature, or meta‑transaction) into the input field, select the network, and click "Check signature". The tool connects to your wallet via the EVM bridge (read‑only; it never signs or sends anything) to fetch the transaction details and decode the calldata. It automatically detects the signature function, extracts v, r, s (or a bytes signature), and identifies the owner, spender, amount, nonce, and deadline. It recovers the signer and performs a series of validity checks. The AI layer then generates a plain‑English summary: whether the signature is valid, what action it authorizes, and any issues that would cause it to fail. You can click on the transaction hash to view it on the block explorer.

PARALLEL NONCE AND DEADLINE VERIFICATION

Unlike simple signature checkers that only recover the signer, this tool performs a multi‑step validation that mirrors the actual contract verification. It fetches the transaction details and decodes the signature function using a library of common signatures (permit, permit with boolean, metaTransfer, execute, etc.). In parallel, it reads the current nonce for the signer from the contract's nonce mapping (using eth_call), the current block timestamp, and the chain ID. It then compares the nonce used in the signature against the contract's current nonce—if the nonce has already been used (nonce > current nonce), the signature is invalid. It also checks the deadline against the current block timestamp. For EIP‑712 signatures, the tool reconstructs the domain separator and message hash (where the contract ABI is available) to validate the exact hash that was signed. If any RPC call fails, it falls back to the next endpoint without stopping the scan. The tool also checks historical failed signature attempts for the same signer and contract to detect patterns like nonce reuse attacks.

WHAT IT CANNOT SEE

This tool cannot detect invalid signatures that depend on off‑chain state (e.g., signatures that are invalid due to a missing chain ID mismatch that is not present in the data, or signatures that rely on off‑chain signature aggregation). It cannot predict future nonce changes or state changes that might make a currently valid signature invalid by the time it is mined—the check reflects the current block, not the future. It cannot verify that the recovered signer is the intended signer—the tool reads what is on‑chain, not the user's intent. It cannot detect signatures in contracts that use non‑standard signature verification (e.g., ERC‑1271 contract‑based verification, or custom validation that is not EIP‑712 or standard ecrecover). It cannot guarantee that a retry with a corrected signature will succeed even if the current signature appears invalid due to nonce reuse, because the nonce may already be consumed. It cannot detect if the signature is being used maliciously or if the approval amount is unexpectedly high—this tool only checks structural validity and signer recovery, not intent or security. It also cannot detect signatures that are valid but will fail due to insufficient allowance or balance, as those are separate conditions.

PLEASE NOTE

This tool works only for EVM‑compatible chains (Ethereum, Polygon, BSC, Arbitrum, Optimism, Avalanche C‑chain, etc.) and supports standard EIP‑2612 permit, EIP‑3009, and common meta‑transaction patterns. It does not support ERC‑1271 contract‑based signature validation or custom signature schemes. All explanations are AI‑generated from data the app reads on‑chain—the AI synthesizes the signature components, recovered signer, nonce, deadline, and contract state into plain English, but it does not have special access to private contract logic or off‑chain data. Always review what you are actually signing in your wallet before approving any transaction; a signature validation does not replace your own verification of the transaction details, including the spender address and approval amount. This tool is provided free of charge, with no warranty of accuracy or completeness.