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drmadhupk - I doubt that it can be done. Even if you did find a way to do it then I daresay your students would see it as a challenge and crack it within a couple of days.
Have you considered making your library available via the calibre server so that your students access it via a browser. This is a bit out of date, but I think the gist of it holds true ==>>
How To Access Your eBook Collection Anywhere in the World
BR