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how can i export a PDF with 128-bit AES encryption in LibreOffice Writer? [closed]

asked 2014-04-03 11:33:30 +0200

Delta gravatar image

updated 2016-02-20 18:32:41 +0200

Alex Kemp gravatar image

At this time - in default settings - LibreOffice exports with 128bit RC4. This old stream cipher is not secure anymore and very assailable. I would like to use a modern Encryption Standard like AES. How can i configure that LibreOffice use a more secure encryption.

https://en.wikipedia.org/wiki/RC4
https://en.wikipedia.org/wiki/Advance...

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Closed for the following reason the question is answered, right answer was accepted by Alex Kemp
close date 2016-02-20 18:34:21.159669

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What is your LibreOffice version? See the Help | About menu for version info. Where did you get and info that LibreOffice is using 128-bit RC4 cipher?

L-user gravatar imageL-user ( 2014-04-03 13:43:58 +0200 )edit

I use the versions 3.6.6.2 and 4.1.5.3. You can see this if you open the pdf file in adobe reader and check properties > security.

Delta gravatar imageDelta ( 2014-04-03 14:26:45 +0200 )edit

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answered 2014-04-03 12:37:07 +0200

oweng gravatar image

updated 2014-04-04 01:31:04 +0200

At this time - in default settings - LibreOffice exports with 128bit RC4.

Apologies for initially misreading the question. I imagine LibreOffice uses the encryption in the related version of the PDF specification:

  • v1.1, MD5 or RC4 40 bit
  • v1.4, RC4 40-128 bit
  • v1.5, Public Key Cryptography Standard (PKCS) #7 i.e., SHA-1, RSA up to 4096 bit
  • v1.6, AES, PKCS#7 with SHA256, DSA up to 4096 bit
  • v1.7-extension-level-3, AES 256 bit
  • v1.7-extension-level-8, AES 256 bit with different password handling

At present, LO only supports v1.4 of the PDF specification (in terms of encryption). There is a TO DO note in the source code (/vcl/source/gdi/pdfwriter_impl2.cxx) for v1.5 and v1.6 of the PDF specification. Bug fdo#55425 is possibly related.

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LibreOffice 3.5 Release notes are describing ODF encryption, is there the same encryption for PDF? I don't know, I haven't found out this info.

L-user gravatar imageL-user ( 2014-04-03 13:48:06 +0200 )edit

i talked about exporting PDF! not odf standard file format.

Delta gravatar imageDelta ( 2014-04-03 14:29:00 +0200 )edit
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answered 2014-04-04 10:46:21 +0200

this post is marked as community wiki

This post is a wiki. Anyone with karma >75 is welcome to improve it.

Well you can export the PDF as it is (without pw) and then use pdftk (free software / GPL) and add a password with that. (or many other PDF readers can do this, too)...

Most is already said by @oweng

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Asked: 2014-04-03 11:33:30 +0200

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Last updated: Apr 04 '14