Encrypt and Decrypt PDF files using Java | Password Protect PDF
Encryption is a famous and reliable approach to protect the content of PDF documents. When a document is encrypted, its contents become unreadable, and only authorized users can decrypt the document to obtain access to the contents. When you protect documents with a password, people who enter the correct password can access the file or folder. A stronger security method is encryption, with common types being 128-bit key or 256-bit AES encryption.