Re: Will this scheme work ...

From: payson@dr-hibbert.cs.wisc.edu ( Payson)

Date: Thu, 07 Oct 1993 16:51:59 +0000

In article <TSOS.605.749988109@uni-duesseldorf.de> TSOS@uni-duesseldorf.de (Detlef Lannert) writes:
>In article <1993Sep25.055607.4810@cs.cornell.edu> moudgill@cs.cornell.edu ( Mayan Moudgill) writes:
>
>>The Problem:
>>A group of people are playing a game over e-mail. They need to throw dice
>>every turn. Unfortunately, they can't find somebody ``trustworthy'' to
>>do it for them. So, how can they throw dice
>>
>
>This is not the first nor the best reply to your question ;-) -- but I'd
>like to suggest a *very* simple solution that doesn't require much overhead.
>What it does require is an independent server that regularly broadcasts
>some information which
>
>(a) is sufficiently unpredictable
>(b) does not reach any party *before* a certain date and time
>(c) cannot be forged by any party (without an undue amount of resources)
>
State lotteries ought to be very good for this, if the timing is acceptable.
Fat chance of influencing them, and if one _could_, one would have better
things to do than play dice games. ==:)

>Ok, there are safer and more elaborate schemes around, but they need, as
>far as I know, a lot more communication and some advanced mathematical
>programming. MD5 (and similar hash algorithms), however, are available in
>source form on the net, and the rest of my proposal is very simple and
>straightforward to implement. The most difficult part is probably to agree
>on a source of information (and to type it in without actually buying the
>paper!).

How about everyone picks a number and encrypts it in an unambiguous message
which is encoded using a private-key cipher and a randomly-selected key.
Then everyone exchanges messages.  After everyone has all the encrypted
messages, they exchange keys.  The sum of all the numbers, mod 6, is the
die roll.  Note that the encrypted messages must be long enough to ensure
that there is a unique intellegible decryption for each one
--
-------------------------------------------------------------------------------
 payson@cs.wisc.edu  |  "Je crois que je ne vais jamais voir...  |   J\_/L
 John Payson         |   Un animal si beau qu'un chat."          |  ( o o )

References

Re: Will this scheme work ...
TSOS@uni-duesseldorf.de (Detlef Lannert)
Thu, 07 Oct 1993 10:01:49 +0000
Will this scheme work ...
moudgill@cs.cornell.edu ( Mayan Moudgill)
Sat, 25 Sep 1993 05:56:07 +0000

Referenced By

Re: Will this scheme work ...
TSOS@uni-duesseldorf.de (Detlef Lannert)
Thu, 07 Oct 1993 10:01:49 +0000
Will this scheme work ...
moudgill@cs.cornell.edu ( Mayan Moudgill)
Sat, 25 Sep 1993 05:56:07 +0000