Pu Ronghua app shows that the signature has expired, indicating that the review time of the app developer account has expired or the APP has been updated. When Pu Ronghua APP is running, signature verification is required. If there is no signature, it can't run on the system. If the signature expires, the developer's account can be obtained directly at this time, and can be reused after authentication.
All applications need to be digitally signed by developers with certificates, and unsigned programs will not be installed. Signature plays a very important role in preventing the program from being tampered with after it is released.