There are two encryption methods for PDF files. One is to add a user password, that is, enter the password after opening it. The other is to impose restrictions, that is, to restrict printing, copying, merging and modifying content.
The first one generally requires violent cracking, but it may not be easy to solve.
If it is the second type, you can use online PDFdo, online PDF decryption to remove restrictions, and online search PDFdo.
In interpersonal communication, it is sometimes necessary to write a farewell letter to relatives and friends, calling it a gift. Students have be