Comments on: Energy encryption

By: Eliezer Yudkowsky

Eliezer Yudkowsky — Mon, 29 Sep 2008 09:30:33 +0000

“The old adage ‘knowledge is power’ is a very cogent truth, both in human relations and in thermodynamics.” — E. T. Jaynes

http://www.overcomingbias.com/2008/02/second-law.html

By: Nick Hay

Nick Hay — Sat, 24 Nov 2007 22:41:29 +0000

Given two boxes, one with hot gas the other with cold gas, you can extract energy by eliminating heat differential. However if you let these two gases mix together to form a box of lukewarm gas you lose this ability. (See http://en.wikipedia.org/wiki/Maxwell%27s_demon)

Divide your hot and cold gas into tiny cubes. Make them small enough that you cannot detect their temperature without making either cube lukewarm (say, 1nm^3). Place them in a grid which can permute the cubes reversibly (i.e. without losing any energy, in the sense of reversible computation), starting with all the hot cubes on one side, the cold cubes on the other. Apply an encryption algorithm, using your secret key, to rearrange the positions of the cube.

If you don’t know the key, you cannot extract any energy — you don’t know which cubes are hot or cold, and you cannot find out without destroying the heat differential. As a whole it appears like the box of lukewarm gas in the first example. However, if you do know the key, you can separate the hot and cold cubes without cost, and extract the stored energy.

There are undoubtedly better ways to do this. The more general idea is having a system appear to have high entropy, but actually be a low entropy system carefully encrypted.

By: Mike Linksvayer

Mike Linksvayer — Sun, 18 Nov 2007 22:09:12 +0000

Carl, that makes sense, but I wouldn’t describe the scheme as “encryption”.

By: Carl Shulman

Carl Shulman — Sun, 18 Nov 2007 21:01:37 +0000

I disturbed my over-sensitive mouse while rephrasing:
“I assumed [he meant] to [describe] something”
“destroyed by [the] encrypting entity”

By: Carl Shulman

Carl Shulman — Sun, 18 Nov 2007 20:56:56 +0000

I assumed to something like setting oil wells on fire before they are captured, that would use much of the free energy in one’s domain. The amount of energy that would be destroyed by booby-traps ‘encrypting’ entity and the costs of combat would then determine the gains from trade between potential aggressors and defenders. For instance, if the traps could destroy 25% of one’s reserves, and combat would cost the attacker resources equivalent to 5% of your reserves, then you could cut a deal to very gradually turn over 71% of your reserves in exchange for survival (keeping the ratios steady so that the incentives for the would-be aggressor do not change before you run out).

By: Gordon Mohr

Gordon Mohr — Wed, 12 Sep 2007 07:54:32 +0000

Perhaps if you squint enough a booby-trapped energy store is ‘encrypted’ — if you provide the key to disable the trap, it’s usable; otherwise it dissipates/explodes.

Hmm. And maybe if the key could be brute-forced, but only by spending more energy than it protects, the analogy would be even stronger.

Hmm. Or maybe there’s an element like Maxwell’s Demon involved… the ‘dissipation/explosion’ happens in some ostensibly pseudorandom way that could only be practically harnessed if you knew in advance how to perfectly and dynamically reorient a collector, like the demon and the trapdoor.

By: Mike Linksvayer

Mike Linksvayer — Tue, 11 Sep 2007 20:46:09 +0000

some energy could be stored in such a way that it can only be recovered via the decryption key

How? Sounds interesting even if it isn’t a useful defense.

By: Peter McCluskey

Peter McCluskey — Tue, 11 Sep 2007 19:14:40 +0000

I asked Ralph Merkle about energy encryption, and he says some energy could be stored in such a way that it can only be recovered via the decryption key, but there’s still a lot of energy that would be available to the attacker. For instance, the attacker could still gather up all the hydrogen atoms and use them for fusion. So the value of this defense is questionable.

By: Mike Linksvayer

Mike Linksvayer — Mon, 10 Sep 2007 05:01:02 +0000

Yes, ‘encryption’ is an odd description. The only way I can see it making more sense than destruction (preferably aimed at the attacker rather than just making resources unavailable) would be if a remnant can ‘decrypt’ the energy after the threat has passed, which is even more fantastical.

By: Gordon Mohr

Gordon Mohr — Sun, 09 Sep 2007 20:52:27 +0000

‘Energy encryption’ is an odd way to describe the more general need of deterring energy theft. A simple energy-defense strategy would be a credible threat that you can and will destroy your energy store rather than let it be taken (even without any implication of poisoning the predator). “Live free or die.”