whenever a file is read (for viewing and/or writing and/or executing purposes) it should ask password.

I have ubuntu 12.04 lts (Long term support) installed into my computer system. Whenever a file is read (for viewing and /or writing and /or executing purposes) it should ask password. it should also ask for two numbers and add them in a subroutine and display the sum and then authenticate it and then the file should be read. for ex. I have a file in Desktop directory by name abcd, its path is /home/mvrp/Desktop/abcd. I request you to use / so that any file opened will be covered.