50% is 50%

Chris (cr@innocent.com)
Wed, 11 Jun 1997 18:59:43 -0400


----------
: From: saurvok@exo.com
: To: deschall@gatekeeper.megasoft.com
: Subject: Re: Other Efforts
: Date: Wednesday, June 11, 1997 2:10 AM
:
: At 12:38 AM 6/11/97 -0400, you wrote:
: >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).

Saurvok@exo.com

: I disagree.
:
: Its true, over many many contests on average it wouldn't matter.
: But this is 1 contest....and the key could be at the end..or middle..or
: start....
: .pick the wrong sequential method and you could spend alot more time then
: the average 50% of key space. So, picking a key randomly from the entire
: space each time (assuming no duplicate picks) will give the average 50%
: time..no matter where the key is.

What? This makes no sense whatsoever. The RSA site says that this is a
totally random key, therefore psychology is meaningless. You are correct
that a random key "will give 50% average" no matter where the key is. This
is the exact same thing for sequential keys a 50% average. Even for small
numbers this works. Random guessing will do no better or worse than
sequential. This is a math FACT. It is easily proven. You can do an
experiment with cards or coins and prove it to yourself. Sequential is
random. Assume a head (sequential try 1) (a) followed by a coin toss (b)
followed by tail (sequential try 2) (a1) followed by a coin toss (b2). Do
this process as often as you like, it doesn't matter on average you will
match a with b 50% of the time.

No matter how HARD YOU TRY, TRY, TRY, TRY, TRY to guess a you will never do
better or worse than any sequential method on average, not trying HHHHHHH,
not TTTTTTT, not HTHTHTTTTTHTHTHHHHHHHHHHHHHTTTTTTTTTTTTTHTHTHTH, it
DOESN'T matter, not for the 1st, second, third, fourth, or zillionth toss.
You can do this with whatever you want and it doesn't matter.

The logic is not there. When someone says suggests flipping a coin to
settle a dispute, and they pick heads or tails you could say "Hey that
isn't fair, you got two choices and I got none"

-Chris