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From "Dennis E. Hamilton" <>
Subject RE: [RELEASE,CODE]: Bug 119090 - Default Encryption Fails for Down-Level Implementations
Date Tue, 27 Mar 2012 01:48:35 GMT
I confirmed my hypothesis.  When AOO 3.4 is installed over the top of an existing (i.e.,
3.3.0) installation, it does not updated the registrymodifications.xcu that is already there.
 Since there are no settings of options for Save As Password use of SHA1 and Blowfish there,
none are there after the AOO 3.4 install.  That means only the program-set defaults will kick
in and the user will be converted to "Save with Password" using SHA256/K checksums and AES256
CBC encryption.  

I verified this with AOO 3.4 r1303653 atop OO.o 3.3.0.

 - Dennis

PS: I also confirmed that LibreOffice 3.5.0rc3 is adding chaff to XML files that are compressed
and encrypted, preventing easy access to known plaintexts for attacking the encryptions in
the ODF package.  (There is a discussion of chaff, among other technicalities at <>.)

-----Original Message-----
From: Dennis E. Hamilton [] 
Sent: Monday, March 26, 2012 17:16
Subject: RE: [RELEASE,CODE]: Bug 119090 - Default Encryption Fails for Down-Level Implementations

I did more experiments with AOO-dev 3.4 and LO 3.5.0rc3 which I happened to have installed
where it was easy to test them together.


 1. It is possible to change the default behavior of AOO-dev 3.4 and LO 3.5.0rc3 (both of
which produce AES 256 CBC and SHA256-1k encryptions by default) by setting options in registrymodifications.xcu.

 2. If registrymodifications.xcu is deleted, a new one is created *but* it has *no* settings
for the SHA1 and Blowfish in ODF12 and these installations *revert* to AES256 CBC and SHA256-1k
even if their last use was with options set for Blowfish CFB and SHA1/1K.

HYPOTHESIS **CONFIRMED**: If an install is done on top of a previous installation not supporting
AES to update to a later version, no settings for this will be added to the "legacy" registrymodifications.xcu
and the default will go into effect: encryptions will start being done in AES256, surprise,


 1. It looks like registrymodification.xcu is the place where a tool or script can do the
job when it comes to setting/changing the desired option.

 2. It looks like there must be code changes to set the default to Blowfish and SHA1/1K within
the application to cover the case where registrymodification.xcu doesn't specify an option
either way. 

 This last may be in Common.xcs but I am betting that the assured default setting is in the
constructor initial values in savopt.cxx.  Why?  Because that class holds the options and
setters and getters for them.  Other software uses the setters when processing configuration
parameters from elsewhere, with the default value delivered by the getter when no configuration
parameter provides a change.  My money is on that being the place.

 - Dennis

-----Original Message-----
From: Dennis E. Hamilton [] 
Sent: Sunday, March 25, 2012 18:15
Subject: RE: [RELEASE,CODE]: Bug 119090 - Default Encryption Fails for Down-Level Implementations


I was doing some nosing around and, based on some information on the Community Forums (thank
you Hagar), it looks like the settings are controlled in a file called registrymodifications.xcu,
at least on Windows.  The location will vary with different versions of windows.

On windows, you can find one under the installed-user profile, such as Documents & Settings\orcmid\Application
Data [a hidden file], OpenOffice/3/user/registrymodification.xcu for any install since the
AES256 has been instituted as default.  the *.xcu is actually an XML file and you can find
the settings by searching for "blowfish" and for "SHA1".

How this works for Mac, Solaris, OS/2, and the various Linus and BSD builds, I have no idea.

 - Dennis

-----Original Message-----
From: TJ Frazier [] 
Sent: Friday, March 23, 2012 11:26
Subject: Re: [RELEASE,CODE]: Bug 119090 - Default Encryption Fails for Down-Level Implementations

[ ... ]

... options to consider:

3. User change to config file, to use the new option.

I have suggested a writeup on this, but such instructions are much 
better aimed at the (few?) users who want the "latest and greatest" 
security option, and will do a little work to get it. (Does anybody know 
what that file name is? Given that, I volunteer to update the Release 

4. Macro to toggle the settings.

This could be distributed in a BASIC library (new or existing); no 
extension necessary. User instructions to find and run the macro are 
simple. I may be able to write this; preliminary investigation is 
promising but not certain. I volunteer to try. There are several real 
experts on this list, whom I might ask for help.

> [1]
> On 19.03.2012 14:48, Jürgen Schmidt wrote:
>> On 3/19/12 2:16 PM, TJ Frazier wrote:
>>> On 3/19/2012 08:48, Jürgen Schmidt wrote:
>>>> Hi,
>>>> I think issue 119090 is no show stopper from my point of view. The new
>>>> default provides a better security than before when I understand it
>>>> correct. And if people detect potential problems they can save the
>>>> document again with other settings.
>>>> I agree that this is important for interoperability but no show
>>>> stopper.
>>>> Any other opinion?
>>>> Juergen
>>> Hi, Jürgen,
>>> Like Dennis, I'm nervous about this. Perhaps we can handle it with a
>>> mention in the Release Notes; something like,
>>> PLEASE NOTE: the default options for [technical details here] should
>>> provide your best /individual/ security. However, if you intend to share
>>> the document in secure fashion, the default mode cannot be read by
>>> * previous versions of
>>> * current versions of LibreOffice, at least through [version]
>>> * Ms Office [version info]
>>> For compatibility, use the options [details here].
>> I agree that it make sense to mention it in the release notes.
>> Any volunteer for updating the release notes?
>> Juergen

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