It is possible for older encryption (not AES256): get the source code
and have a look at StandardSecurityHandler.java. There is a segment
where "isOwnerPassword()" is called, and a bit later, "computedPassword"
is calculated by calling getUserPassword(). I tried this by debugging
with out test files and yes I got the user password.
So you could do it by 1) get length, revision and owner key from the
PDEncryption object you get by calling document.getEncryption() 2) check
that revision is smaller then 5, and 3) call getUserPassword().
Tilman
Am 03.01.2018 um 09:29 schrieb Hesham Gneady:
Hello,
I have a PDF file that has an owner password & user password. I'd like to
decrypt it using the owner password, make some modifications to it, then
encrypt it back and save it. I did the first part successfully, but how can
I encrypt it again using the same encryption settings it had, which I don't
actually know? . For example, I know only the owner password, but not the
user password.
Best regards,
Hesham
---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
