Re: Getting random die rolls for a pbm game

From: dodd@polya.Stanford.EDU (Christopher T. Dodd)

Date: Wed, 03 May 1989 21:10:45 +0000

Actually, you can do this reliably, without using public key
crypto, and without requiring passwords to be mailed around (where they
can be intercepted fairly easily).

To do this, you use a list exchange method as described in a
previous article, exchanging lists of A-F, with a pre-agreed upon method
of turning pairs of letters into die rolls.  First, however, you encrypt
the lists (using crypt(3) or something similar) and exchange them.  When
both parties have the encrypted lists (which are unreadable), they send
the same list in the clear.  Each person verifies the validity of this
second list by encrypting it in the same way and verifying that the list
hasn't been changed.  The only problem with this is that it requires 2
letter exchanges to resolve a turn's worth of rolls.

----------------------------------------------------------------------
Chris Dodd
dodd@polya.stanford.edu

----------------------------------------------------------------------
/* short program to encrypt standard input */
#include <stdio.h>
#include <ctype.h>

char *crypt();

char salt[] = "fu";

main()
{
char	code[9];
int	i,ch;

i = 0;
	while((ch=getchar())!=-1) {
		if (isalnum(ch)) code[i++] = ch;
		if (i==9) {
			code[i] = 0;
			printf("%s\n",crypt(code,salt));
			i = 0; } }
	if (i!=0) {
		code[i] = 0;
		printf("%s\n",crypt(code,salt)); }
}

References

Getting random die rolls for a pbm game
LK-HANNU@FINTUVM.BITNET (Hannu Pajunen)
Tue, 02 May 1989 14:00:28 +0000
Re: Getting random die rolls for a pbm game
matt@oddjob.uchicago.edu (Matt Crawford)
Wed, 03 May 1989 00:33:14 +0000