Re: [libreoffice-users] the password of Libreoffice

On 09/11/2013 07:09 AM, tangchaojie wrote:

> I Forger My password of the Libreoffice file . 
> Who can tell me how to deal with it ?

LibO 3.4.5 and lower can write files whose password protection relies on
Blowfish;
LibO 3.4.4 and lower can read files whose password protection relies on
Blowfish;
LibO 3.4.5 and higher can read files whose password protection relies on
AES-256;
LibO 3.5.0 and higher can write files whose password protection relies
on AES-256;

The Crypto++ library contains routines for encrypting/decrypting
blowfish, AES-256, and other algorithms for ciphers.

In 2001, four or five firms, worldwide, offered commercial OOo password
recovery services.

One of the firms frankly admitted that they used brute force. The setup
fee paid for the computers used for the "attack". The monthly fee
covered the utility bills that the "attack" generated. FWIW, this firm
now appears to be out of business.

http://openoffice-password-recovery.en.softonic.com/ offers a tool that
they claim:
« OpenOffice Password Recovery is a software program to restore any
forgotten passwords from any document created with Open Office. This
tool supports all Open Office applications including OpenOffice Calc,
Impress, Math, Writer and Draw.
OpenOffice Password Recovery also features protection removal so you can
get rid of the read-only restriction used for protection with some files. »

http://openoffice-password-recovery.sharewarejunction.com/ offers an OOo
extension for US$79.00 that allegedly recovers passwords from OOo
documents.

Those tools might work, but I have my doubts. Whilst there are known
attacks that result in determining the password faster than using brute
force, those attacks require at least a century to complete, using
Beowulf Clusters that are currently commercially available.

jonathon
-- 
LibreOffice in a Multi-Lingual Environment.

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