How is Acrobat DC document encryption and protection so easily cracked?

[Phil25749790i279]

We would like to protect certain PDF documents from copying, modifying, printing, converting to Word using encryption and a permissions password.

I have successfully tested this functionality to my satisfaction using Acrobat DC to try and modify test documents.  However, if I try free online tools to convert PDF to Word, they seem to be able to crack the protection with little or no problem - and example is [ Admin: removed link ] which converts an encrypted file protected with a 40 character complex password in seconds.  Others ask for password or get stuck during the process (as if they are attempting to brute force the password) but smallpdf.com breezes such files.

So, what is the point of this Acrobat functionality if it is so easily circumvented?

I would be grateful of any advice on how to properly protect my documents.

[Karl Heinz Kremer]

The password based security in Acrobat has different levels, and the more advanced encryption level you pick, the harder it gets to crack the password. If you want more security, select a certificate based protection. 

[Phil25749790i279]

Hi Karl Heinz, thank you for your reply and sorry for taking a while to acknowledge.

I have experimented with certificates and can certainly see an improvement on the crackability of the PDF using this method - if just fails the smallpdf.com tool - which is a step forward.

I need to work out how to apply the certificate just to the permissions level of security so the PDF cn be opened without the certificate.

Cheers,

Phil

[Phil25749790i279]

Does anyone know if it is possible to apply certificate-based security to just the permissions but leave the document able to be opened without a certificate or password?

[Karl Heinz Kremer]

As far as I know, it's one or the other, and you cannot have a combination of both.