General Discussion - PDF AES encryption ?

PDF AES encryption ?

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Category: For Users of the Library
Forum Name: General Discussion
Forum Description: Discussion board for Debenu Quick PDF Library and Debenu PDF Viewer SDK
URL: http://www.quickpdf.org/forum/forum_posts.asp?TID=1311
Printed Date: 22 Nov 24 at 11:03PM
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Topic: PDF AES encryption ?

Posted By: lepoutre
Subject: PDF AES encryption ?
Date Posted: 10 Jan 10 at 2:04PM

Hi,

I have understood that the recent versions of quickpdf enjoyed a "128-bit AES encryption" option. Nice addition.

The older pdf formats -pre 8.x - would encrypt the text base but not images included in the pdf. And I am looking for accross-the-board encryption. I'd like to hear whether the more recent PDF AEAS encryption does incorporate embedded bitmaps.

A very satisfied user of the legacy product and possible commuter to the new product:)

Replies:

Posted By: lepoutre
Date Posted: 10 Jan 10 at 3:01PM

To be more specific, I want to make sure that the images embedded in the pdf (currently jpeg and/or png via AddImageFromFile) are duly encrypted within the PDF file.

My understanding is that these files were embedded as-is. Has this changed ? Is quickpdf embedding those pieces "as-is" or encrypted?

Posted By: Ingo
Date Posted: 11 Jan 10 at 6:45AM

Hi!

As you can read here:
http://www.quickpdflibrary.com/help/quickpdf/Encrypt.php
It's the text that will be encrypted.
I think that's the normal way and according to the pdf-specs 'cause i've never had problems to decrypt an external aes-pdf-file with images and text?

Cheers, Ingo

Posted By: lepoutre
Date Posted: 11 Jan 10 at 7:41AM

Hello Ingo,

Thank you for your input. I take it that only the base document is currently encrypted excluding files embedded with addimagefromfile() and embedfile() function.

I am certainly no pdf-format guru. But my understanding was that the document was - at least in current versions possibly starting with version 7 - fully encrypted including attachements. That is what I grasped from the text below concerning encryption scope on recent versions. Am I wrong?

Can we expect more complete AES encryption later this year when debenu starts coding their AES-256 support. I'd be glad to hear that quickpdf-generated documents could behave like Fort Knox once a long enough password is devised:)

http://help.adobe.com/en_US/Acrobat/9.0/Standard/WSD012A4E1-51D1-4bcd-BA9F-EF03C6F20BB6.html

"Encrypt All Document Contents

Select this option to encrypt the document and the document metadata. If this option is selected, search engines cannot access the document metadata.
Encrypt All Document Contents Except Metadata: Select this option to encrypt the contents of a document but still allow search engines access to the document metadata. This option is available when you select a compatibility to Acrobat 6.0 and later.
Encrypt Only File Attachments: Select this option to require a password for opening file attachments. However, users can open the PDF without a password. Use this setting for security envelopes. This option is available when you set compatibility for Acrobat 7.0 and later."

Posted By: Rowan
Date Posted: 06 Aug 10 at 10:12AM

Hi Guys,

Currently, when Quick PDF Library encrypts a document all the content is encrypted -- page content, images, file attachments, etc.

Using the "crypt filters" feature in the PDF specification you can selectively encrypt parts of a PDF. That's useful when you want everything encrypted except for certain things. For example, if you don't encrypt the metadata then search engines will still be able to find things - but the rest of the document will be secure.

Quick PDF Library does not currently support crypt filters.

What Quick PDF Library does currently do is encrypt all string and stream objects in a document. Since image data is stored in a stream object, it will be encrypted. File attachments are also encrypted.

However, objects like numbers are not encrypted - so things like the image width and height will not be protected.

Cheers,

- Rowan.