OSX - Timed File Lock

Want a OSX application that will let a user choose a file, and then the application makes that file inaccessable until after a duration of time. User has various options to control the time interval and the display of the countdown clock. Application must be able to calculate the time elapsed so that the application does not have to be open all the time. Just open to update the countdown clock. In addtion, there is an element of suspense available, so numerous random generators and display options. Please view the two attachments, I believe I have detailed what I'm looking for including what I would like the final windows to look like.