This is just a stab in the dark, but...

Is this calculating some kind of security key to validate that you are an authorized user of their application? If so, they probably won't thank you for publicizing the code, and you may be unable to get it working in perl since a differently functioning rand library may be used than whatever it is that they have. Why are they sending you the code rather than asking for information on your drive setup and calculating the number for you? (Perhaps you are redistributing to an unknown setup?)