How this works
This uses the standard PDF security handler (V4/R4, 128-bit RC4) — the classic Adobe encryption scheme every PDF reader supports, including print and copy permission controls you can enable or disable independently of the open password.
Common questions
Is 128-bit RC4 as secure as the newest PDF encryption?
It's weaker than the newest AES-256 scheme some modern software defaults to, but still requires the correct password to open in any compliant reader — for typical personal or business use it's more than sufficient; for very high-security needs, a dedicated tool with AES-256 would be stronger.
Can I let people view the PDF but block printing or copying?
Yes — printing and copying are separate permission flags from the open password, so you can require a password to open the file while still allowing or blocking printing and text copying independently.