How can I decrypt a Microsoft Word document for which I have the key?

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As per a suggestion from another group,
(http://groups.google.com/group/microsoft.public.security/browse_thread/thread/d82c615b3863c54c/0b6bba3706025ebb?lnk=st&q=microsoft%20word%20encryption%20key%20crack&rnum=2&;)
I've posted my question here in hopes of a helpful response. Thanks in
advance. :)

Hi all,
I'm rather a novice when it comes to security concerns in the Microsoft

realm, so please bear with me. Here's my situation:

A friend has an old Microsoft Word (97+, I am guessing) document for
which she has set an "open document password." That is, the file is
password-protected and encrypted. She has forgotten the password for
the file and now needs to open it, but can't without cracking the
security protection she has already placed on it. I have never before
even attempted anything like this, but figuring it a good opportunity
to learn something I took it upon myself to see if I could help.

My research uncovered a plethora of Windows-based tools (applications)
which promise to recover the password if I buy the full version of the
program, but since this task is largely for my own edification it would

be utterly pointless just to pay for a program. Nevertheless, I tried
to the demo versions of plenty of these programs. One proved fruitful:
it has managed to recover the encryption key used on the document.

So now I have learned several things about the Word document. Firstly,
the password is more than five characters long. Secondly, that it is
likely a "modern" version of Microsoft Word. Thirdly, and I am assuming

most helpful, I know the precise encryption key.

Knowing these things, especialy the encryption key, how can I now
decrypt the document and read its contents?

Thanks in advance for pointing me in the right direction.
Regards,
-Meitar

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