Open Excel locked file using password without office installed
 

Hi,

I am building an application that recieve excel files from clients, extract
the data from it and store in on DB after verifying the data integrity and
several other data manipulations.
In order to get the correct data and avoid "cheats" I lock the excel (when
sent the files without the lock it caused many problems with retrieving the
data and with the data integrity)

The problem is that in order to retrieve the information from the excel I
use Ole connection, that cannot open the file if it is locked.

I cannot use excel application or excel to unlock the file as the server has
no office installed on it, and the excel application is not a usfull tool for
a server (will pop up messages on bugs that will need to be handled by hand
etc.)

Is there a way to unlock an excel file (using the correct password) on code
(c#...)?
Or is there another way to protect the cells from buing handled with beside
locking the excel?

(if I should post under a different topic, please update me)

Thanks,
Yaron.