How to impose expiry date on MS Office files?
 

General Idea
------------------
We are trying to develop a web application for document management using
ASP.net (C#, Framework 2.0) and document libraries in MOSS 2007 for storing
the documents that impose IRM settings like READ, EDIT, PRINT, etc., while
downloading the document. This part is done.


Problem area
--------------------
We have an additional requirement, that is to impose expiry date on the
documents at the time of upload-to or download-from document library.
Every document can have different expiry date, after that user should not be
able to open the document.
Type of document could be any thing, but initially we have to do this
activity for MS Office documents only, like .doc, .docx, .xls, .xlsx, .ppt,
..pptx and infopath, etc.


Possible Solutions
---------------------------
1. Restrict the user to download the document after expiry date is simple
and done.
2. After a user downloads the document, it has no relation with the
application and (I think) what ever (IRM) permissions imposed applied by RMS
server attached with MOSS are stored in to the documents meta data, where
expiry date too can be stored. Suppose the user has downloaded the document
today that has expiry date tomorrow, if he/she tries to open it there after,
the document should not open. This is already done in existing system by some
vendor and we are going to up-grade the same system using .Net framework 2.0
and Microsoft Office Share point Server (MOSS) 2007. Since the system already
has that functionality available and the customer needs it for valid reasons.

Please guide

--
sachin