Re: Other Efforts

Justin Dolske (dolske@cis.ohio-state.edu)
Wed, 11 Jun 1997 00:38:34 -0400 (EDT)


On Wed, 11 Jun 1997 techs@obfuscation.org wrote:

> for the single effort (not a combined effort of three (or more) groups,
> splitting the keyspace into oh... 8 groups, and then working away from
> those 8 marks in both directions and handing out keys gives a better
> coverage of the entire keyspace than working from one end toward the other.

The order the keyspace is searched in doesn't matter. All orders are
just as good. (Let's ignore the complication of multiple efforts searching
the keyspace for now).

Consider this example... I tell you someone is hiding behind the closed
door of a random room in a large hotel, and you are to find them. What
order do you search in? You look behind door number 1. Noone is there. Now
where to look? Door 2? Door 10? Door 1000? It doesn't matter, the hiding
person could be behind any of the doors.

I think the common trap people fall into is trying to "second guess"
where the key must be... Ie, you assume the "key-hider" has anticipated
where you are going to search. For example, suppose you start searching at
the beginning. The smart opponent will put the key at the end, so it takes
a long time to find it there. Ahh, but you anticipate this, and actually
start searching at the end. Whoops, the opponent thought you might do
this, so they put the key in the middle. Ah-ha! You're smart too, so you
next look in the middle. Your opponent laughs at your predictable
behavior, and actually places the key half way to the beginning. But you
considered this move too, so.... Ad nausium.

There's probably a nice fairy tale with a moral in here, but I can't seem
to find it. It wasn't at the end of the story. Maybe it's in the front...
Nope. Let's try the middle...

:-)

Justin Dolske <URL:http://www.cis.ohio-state.edu/~dolske/>
(dolske@cis.ohio-state.edu)
Graduate Fellow / Research Associate at The Ohio State University, CIS Dept.
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The voices in my teeth tell me I'm paranoid -- but I don't believe them.