So I am going to ask sort of an obvious question here, but maybe the answer isn't so obvious.  What is the right way to "roll" the die?  I was thinking of just dropping casino quality die from about 10cm above a hard surface.  Is this the best way?  Is there a best way?

The dice rolls are secure as long as no one else is in the room, and no one else is watching you roll or can see the dice. The computer you use is secure as long as it is offline and is properly wiped or erased or encrypted or everything is run in RAM then completely powered off.

To "properly" roll the dice means you should throw it across the room, and record only the ones that bounce back from the opposite wall. (Or roll it on something similar to a craps table, where it has to bounce from the other side.)