(057) Strongbox common sense?

[Ghost Post]

I've ignored other problems on here that had trivial flaws, but this one takes the cake. I just HAD to register and post.
Puzzle 57. Common sense just blows away this entire strongbox question. The whole concept is unworkable as presented.

First, if you can't securely leave a key, then you can't securely leave instructions on how to perform the sale. Someone else will get the instructions and steal the diamond from you.
Ideally:
A)You leave note in insecure box. B)Buyer gets note.
C)Everything occurs as in the solution from here on.
In the real world:
A)You leave note. B)Some snoop reads the note and pockets it. Perhaps he leaves a fake note with different instructions; perhaps not.
C)Buyer doesn't get the [correct] note.
D)Everything occurs as in the solution, except the snoop uses his lock and steals the diamond.

Not good. Then, of course, there's the matter of people putting their locks on locked boxes and leaving them there forever, just out of random spite. Hehe. Time to buy a good lock-cutting tool. However, this would probably be frowned upon by the library staff and passerby.

There's also the issue of making the payment, which is never really mentioned. You could just use two strongboxes, but how do I know that the buyer isn't cheating me? If you don't trust each other enough to reveal identity, how can you trust each other to not cheat?
A)Lock diamond-filled box. B)Wait until the diamond and money boxes are locked by the buyer. C)Move my lock from the diamond box to the money box. D) Wait for both boxes to be unlocked. Buyer has taken the diamond. E) Remove my lock and discover the empty money box.

We could go the other way, letting the buyer lock up the money first, but then I could cheat him out of the diamond. Whoever locks their box first risks being cheated. I suppose the eccentric knows your identity and could have nasty things done to you if you renege... So the thing to do is to have the eccentric lock the money first. If you cheat him, you'll regret it.

Any flaws in the above?

[Ghost Post]

I would think they want you to consider a "perfect" world, so even the most unlikely solutions are the definite answers.

[This message has been edited by PyroGx1133 (edited 10-26-2001).]

[MatrixFrog]

Exactly. Sometimes you have to idealize a bit for puzzles.

Another note about this puzzle: I read somewhere that this is how some very high-security online transactions are carried out, metaphorically speaking. One computer encrypts it, then the other does, then the first decrypts it, then the second. Of course, the encryption method would have to be commutative.

[Antrax]