PDF-Export not secure?

henry_hl · Newbie Joined: 16 Mar 2006 Posts: 3

PDF-Export not secure?
I have created a document using writer (2.0.0 under WinXP) , in which I have incorporated several scanned pages (as jpg)
These pages contained some personal information which I blocked drawing lines over it. Bringing them to the foreground.
With the other written information I exported the document as ".pdf". Worked fine, looked good.

No I have had two reports that those lines can be easily moved using the "grab" tool, thus making it possible to view the hidden information (This in the pdf-file !!!)

The two setup reported were:
a; opening the file using Word2000
b; opening the file using AcrobatReader 4.0 under Win2000

It was NOT possible to move the lines using AcrobatReader 6 and 7!

Any idea where the bug is or what I did wrong?

HL

P.S: Anybody wanting to try it out, the file (it's not that secret, really) can be found at:
[url]http://people.freenet.de/uplifting/SL_down/ClearingBogen.pdf
[/url]. Please let me know your setup, if you can 'crack it too'.

jrkrideau · Posted: Thu Mar 16, 2006 6:40 am Post subject: Re: PDF-Export not secure?

nickh · General User Joined: 07 Mar 2006 Posts: 9

There is no bug. Your document is being saved correctly as an image with some lines over it, and so the underlying information is still there. You would be much better off drawing the lines on the actual scanned image itself, so that the text is truly overwritten.

hol.sten · Posted: Thu Mar 16, 2006 10:47 am Post subject: Re: PDF-Export not secure?

Bhikkhu Pesala · Posted: Thu Mar 16, 2006 3:03 pm Post subject:

Even easier: I just opened the PDF in Acrobat Reader, selected the image and copied it to the clipboard. Then I pasted it into Irfan View.
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Warrick Nelson · Posted: Fri Mar 17, 2006 1:48 am Post subject:

Opening the pdf in ghostscript, it was obvious some text was still present underneath the lines as the lines showed after the rest of the image was rendered. By quickly pressing "PrintScreen" before the black lines showed, I could paste into a graphics package to read the underlying text.

yuki · OOo Advocate Joined: 20 Oct 2005 Posts: 264

A bug or not, it is worth considering that PDF is not an image format. Export your files as images, and nobody can get the information under the black bars. Just because Adobe Reader would not let you edit the files, does not mean they cannot be edited... Saying this, you could change the security using the full version of Adobe, to prevent copying and modification (not sure whether this is safe...). I did the same as Bhikkhu Pesala, although before reading it here...

henry_hl · Newbie Joined: 16 Mar 2006 Posts: 3

Thanks for the replies.

I had just been under the impression .pdf documents were safe from such manipulations. Just will have to create the (combined) images separately in future.

hol.sten · Posted: Fri Mar 17, 2006 8:31 am Post subject:

Jallan · OOo Advocate Joined: 16 Jan 2006 Posts: 267

thetargos · Posted: Wed Aug 09, 2006 10:09 am Post subject:

I too have noticed this lack of security from OOo's PDF exporter. I for one would love to be able to state in the PDF export dialog whether the content could be copied/selected in the produced document or not, as some times (and I'm sure I am not the only one) people will need to distribute information in a "secure" manner, as read-only, by that meaning that it should not be possible to extract any further information from the "document". Sure, making a JP2 or MNG would be better (layered JPG, or PNG) as each page would be an image, still PDF spec provides such security features... Just the OOo exporter does not use it.

pitonyak · Posted: Wed Aug 09, 2006 10:39 am Post subject:

A PDF file is nothing more than a Post Script file with certain wrapping. Even if you draw lines over text, if it is text, I can probably read the PDF file myself to see the data.
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