Users typically encrypt their PDF files when they want to protect the contents of their documents, be they confidential, private or compromising.
PDF already supports the well-known creator and user passwords, but they can be eventually broken when the appropriate decryptor is chosen.
PDF encryptors will offer users the possibility to protect the files by relying on a list of public keys which will prevent unauthorized users to explore the PDF.
These applications can also be used to process several PDFs simultaneously, thus reducing the time it takes to encrypt the documents.