Skip to main content
A
Anonymous
January 9, 2016
Answered

So how do I decrypt a PDF?

  • January 9, 2016
  • 3 replies
  • 20894 views

I already know the password, but I want to decrypt it so I can view it on mobile devices. The password only works if the file is in the same folder as a certain PFX file. But in any OS other than Windows, this is completely meaningless, and thus I can not view the file even though I know the password. How can I decrypt such a file?

Forgive me if this is the most ignorant question ever.

This topic has been closed for replies.
Correct answer Test Screen Name

This whole issue is so stupid. I downloaded these PDFs from a website which clearly is trying to disseminate them and has clear instructions for how to open the files. I don't know why they bothered with this encryption business to begin with. Presumably only to make me suffer.

In any case, thanks to everyone for the responses. I appreciate your time.


This is a form of Digital Rights Management (DRM). They have clearly done this to stop files from being shared, and if anyone could decrypt the file then the file could be shared. So you can't. DRM is (some googling will show) a HUGELY controversial thing.

3 replies

A
Anonymous
January 24, 2016

Thanks for the replies guys.

Yeah it uses certificate security.

Bernd Alheit
Community Expert
Bernd AlheitCommunity Expert
Community Expert
January 24, 2016

‌Acrobat Reader for mobile devices doesn't support this.

T
Test Screen Name
Legend
January 24, 2016

Bernd, I think that's why the original poster wants to decrypt it, so the unprotected file can be read on a mobile device.

But, I may be wrong, I think you would need the original certificate used to make the file to do that. I think one design aim of certificate security is that you cannot take it off.

Bernd Alheit
Community Expert
Bernd AlheitCommunity Expert
Community Expert
January 10, 2016

Did the document use certificate security?

T
Test Screen Name
Legend
January 10, 2016

Do you have Acrobat Pro?

Whether you have Acrobat Pro or Reader, please open the file and use File > Properties. Under the security tab, what does it say for "Security method"?

Terms & ConditionsAccessibility statement
Using the community Terms of use Privacy Cookie preferences Do not sell or share my personal information ad choicesAdChoices