How does php determine whether a pdf file is encrypted is a permission password, that is, it can be viewed and cannot be modified? I am working on a conversion program. if it is encrypted, it will be stuck there, if the problem persists, the project may be aborted... ------ solution ------------------ after encryption, there will be a sign of encryption. if you know the encryption principle, you can find the language in which the encryption mark is used, this is not a problem. how does php determine whether the pdf is encrypted?
It is a permission password that can be viewed and cannot be modified.
I am working on a conversion program. if it is encrypted, it will be stuck there. if it is not solved, it may directly lead to a project abortion...
------ Solution --------------------
Encrypted, there will be a sign of encryption
If you know the encryption principle, you can find the encryption mark.
So what language is used is not a problem
