Re: The Elevator Problem

Ok, here was the method of key generation i was talking about.  With the light 
communications, the idea was to use photons whose waves pulsed in certain 
directions (up/down, left/right, and diagonally) to create a way toommunicate 
much like morse code.  The key used to scramble these communications was 
designed to change the direction the photons of a message pulsated - like 
changing the characters of a message, scrambling it up.  The key consisted of 
three symbols, one for each of the possible orientations, and was fainly 
simple. It was like a one time pad in that the key was never recycled.

The key could be generated by a game of 20 questions, so to speak.  The people 
at either end randomly generated a key.  Then, they asked eiither indirect 
questions about the contents of one anothers key (do you have an odd number of 
up/down symbols in row x, etc), but since the contents of the key were never 
touched on DIRECTLY, no eavesdfropper could determine the key, and it was 
ttally secure.

We, obviously, cannot use the photon as a method of communication, not for th 
e masses.  the undertaking of building such a network from scratch is 
astronomical.  however, if one wwas to use the orientation symbols in ones 
messages, as if they were being beamed, but in an email message instead, one 
could make use of the simple key, and the simple game of '20 questions' to 
generate a totally secure key in a mater of minutes, depending on how long the 
message was and therefore how long the key has to be.  Does any of this make 
sense?

Regards, 
Munster.
---
_________________________________
*!Cheese Doctrine:!*
    Though cultured over time,
and aged to perfection, one must
not yield to produce mold.  One
must also not belittle themselves
by conforming to the "whiz", but
melt over the unprocessed ideas
of Ghuda.
_________________________________

Munster writes:
> Ok, here was the method of key generation i was talking about.  With the light 
> communications, the idea was to use photons whose waves pulsed in certain 
> directions (up/down, left/right, and diagonally) to create a way toommunicate 
> much like morse code.  

Right, this is the main quantum crypto idea of Brassard et al. (See for
example _Applied Crypto_ v.1 pp.408-410)

[...]
> but since the contents of the key were never 
> touched on DIRECTLY, no eavesdfropper could determine the key, 

No, the integrity of the system really depends upon the quantum properties
of light. Among other things, Heisenberg's Uncertainty Principle makes it
impossible for Eve to "eavesdrop" on the photons without affecting them
measurably.

[...]
> however, if one wwas to use the orientation symbols in ones 
> messages, as if they were being beamed, but in an email message instead, one 
> could make use of the simple key, and the simple game of '20 questions' to 
> generate a totally secure key 
[...]

In this situation Eve can read the email traffic without modifying it, so the
game is up.

-Futplex <futplex@pseudonym.com>