ChapterZero

My lab partner just scrapped the counter, and is rebuilding it from scratch, so I have some time to indulge myself. I was just relating to him how I have two PGP keys, one of which I lost the pass phrase for, so I can’t void, and the most recent one which I signed up for last week. So he can look me up on a keyserver, like pgp.mit.edu and get my public key, or he can download it from here. Which got us into a discussion about entropy, because I remembered when you use the Windows version of PGP type software, you have to bang on the keys to generate entropy to be used in generating a random key– the longer you want your key to be, the longer you have bang on the keys for. In Unix, there is an entropy daemon (isn’t that neat– a play on Maxwell’s demon?), which runs in the background gathering up entropy– if the Internet can be trusted– I saw a man page for it on the net. Sounds like a nice idea.

Previously, when I first ran across the idea of an entropy gathering daemon, I was in a creative mood, and I got the idea of a world in which entropy has become the greatest commodity, because technology has advanced to the point where shoddy encryption can be broken relatively easily. In this world, weird things are done routinely, all in an effort to collect valuable entropy; as one example out of countless others, cars are scanned before being sold, and if they get into a wreck, they are scanned again, and the random displacements in the surface of the car is used a source of entropy.

I wonder, is the quantity I’m talking about truly entropy? Well, maybe a better question would be, is there any quantity currently known as entropy in any sense (mathematical, physical, etc.) which coincides with the idea of entropy I’m using. It seems that I’m thinking about randomness. What is the relationship between randomness and entropy? I’ve been told that (physical) entropy is constantly increasing, but I don’t see how that necessarily corresponds to an increase in randomness. That would be like saying randomness is a thermodynamic quantity, which is a pretty weird statement.

Possibly relevant posts:

• Mr. delta says (11/16/2005)
• arrogance, mine (p2) (8/23/2003)
• H (or S) is for entropy (5/31/2007)