How PDF Cryptography Works
When a password is set on a PDF document: 1. A 32-byte salt key is generated along with a validation hash using PBKDF2 (Password-Based Key Derivation Function 2). 2. Indirect object streams (text and images) are encrypted using AES (Advanced Encryption Standard) in CBC mode with 256-bit keys. 3. Unencrypted metadata fields remain accessible to allow PDF viewers to prompt for password entry.Protect your files securely with Protect PDF.