Password protecting a Excel file.

Hi,
I want to make Excel files password protected present in my Unix directory. I have a application which will basically invoke a shell script with a parameter passed. The purpose of shell script would be to pop up a box to enter password. This password will be validated against database entry for the parameter passed to the script from front end application. Once verified, The Excel file will be displayed else a message 'Wrong Password' is displayed. Please suggest a workaround for this scenario or any sample script will be of great help.

Thanks in advance.
Anil Kumar

i believe excel is in binary format, maybe with a help of a unix tool you can do that which im not aware of.