Interface signature is a security mechanism to verify the integrity and authenticity of data. When scanning the code and entering the mobile phone number to send the verification code, the system will verify the requested signature. If the interface signature is invalid, it means that the signature information in the request cannot be verified, which may be caused by wrong signature algorithm, key mismatch or data tampering. In this case, the system will refuse to process the request to ensure the security and reliability of the data.