The software was changed and the digital signature was normal. According to relevant public information, the digital signature of the software is normal, and if the file is damaged, the digital signature is invalid. Digital signature is to ensure that the file will not be modified and destroyed from the time of signature. As long as the signature file is modified, the digital signature will be invalid. Digital signature is a kind of digital certificate, which can prove the legitimacy of code, software, applications and executable files.