How to remove or recover password from a LibreOffice document

I have 2 old documents in ODT format that I either made a typo or forgot the actual password for them. I want to recover the password or simply remove it. What steps (If available) are there to remove such password (and remind me of not put passwords to documents).

About LibreOffice encryption

I found 2 interesting links. From the links Libreoffice seems to use AES (http://en.wikipedia.org/wiki/AES_(cipher) ) as of LibreOffice 3.5. Before that it was blowfish.

• Aveesplace.wordpress
• According to LO mail archive (2012 so recent) a brute force with a Windows program called Accent Office will take:

   Max pwd   Accent OFFICE
    Length   Time Estimate (same conditions)
        5    27m03s
        6    1d19h
        7    173d3h
        8    45y197d

Conclusions:

• AES has no known flaws.
• The only way is to provide the correct password. and you should always save an unencrypted copy on an external media like an USB disc that is kept safe in your house.

First, install xmlcopyeditor from the repositories. Open the content.xml file by right clicking the document from the file manager and choosing Archive Manager as the application.

Open content.xml with xml copy editor, press F11 to properly display the full document and find protected=true. Change it to false and your document will no longer me protected.

It's possible to edit the file with a text editor but it tends to choke and lock up your system for a while.

Although this thread appeared several years ago, the question is still pertinent for some. I arrived here because I was unable to identify a password I used on a LibreOffice document. Fortunately, I had a backup of my home directory in TimeShift and was able to upload the original unprotected file and save it to a USB with a new password. This may not work with all backup apps. Nonetheless, the lesson is the same: use TimeShift and regularly backup your files.