Flush Custom Metadata Signature Structure

To authorize the flushCustomMetadata operation within the MNS service, the user who currently owns the username must generate a cryptographic signature compliant with the EIP-191 standard.

This signature proves the current username owner's intent and authorization to remove all custom metadata entries associated with their username (_username).

Signed Message Format

The signature verification uses the SignatureRecover.signatureVerification function with the following structure:

SignatureRecover.signatureVerification(
    Strings.toString(evvmID),                           // EVVM ID as string
    "flushCustomMetadata",                              // Action type
    string.concat(                                      // Concatenated parameters
        _identity,
        ",",
        Strings.toString(_nonce)
    ),
    signature,
    signer
);

Internal Message Construction

This results in a message format:

"{evvmID},flushCustomMetadata,{identity},{nonce}"

Example

Scenario: Owner wants to flush all custom metadata from their identity "alice"

Parameters:

• evvmID: 1
• _identity: "alice"
• _nonce: 20

Signature verification call:

SignatureRecover.signatureVerification(
    "1",
    "flushCustomMetadata",
    "alice,20",
    signature,
    signer
);

Final message to be signed:

1,flushCustomMetadata,alice,20

EIP-191 formatted message hash:

keccak256(abi.encodePacked(
    "\x19Ethereum Signed Message:\n31",
    "1,flushCustomMetadata,alice,20"
))

Message Breakdown:

• 3ca44e54: Function selector for flush custom metadata verification
• alice: The identity (username) from which all metadata will be removed
• 20: The current identity owner's nonce

This message would then be signed using EIP-191 standard, and the resulting signature would be used to verify the metadata flush request in the verifyMessageSignedForFlushCustomMetadata function.

tip

• The function selector 3ca44e54 is the first 4 bytes of the keccak256 hash of the function signature for verifyMessageSignedForFlushCustomMetadata
• Strings.toString converts a number to a string (standard OpenZeppelin utility)
• The signature verification uses the EIP-191 standard for message signing
• Only the current owner of the identity can flush all custom metadata from their identity
• This operation removes all custom metadata entries at once, unlike removeCustomMetadata which removes specific entries
• The _nonce parameter is the user's general nonce, similar to the remove function