Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!execu!sequoia!rpp386!woody
From: woody@rpp386.cactus.org (Woodrow Baker)
Newsgroups: comp.lang.postscript
Subject: Re: Info on using eexec
Summary: yup
Message-ID: <17883@rpp386.cactus.org>
Date: 7 Feb 90 18:37:32 GMT
References: <31604@shemp.CS.UCLA.EDU>
Organization: River Parishes Programming, Plano, TX
Lines: 66

In article <31604@shemp.CS.UCLA.EDU>, david@oahu.cs.ucla.edu (David Dantowitz) writes:
> 
> 
> Does anyone have info on using eexec.  An older copy of the red book
> mentioned it (briefly) but the new version has nothing.
> 

Yep. A routine has been posted on the net to decrypt the eexec data into
plain text, and also convert plain text to eexec data.  I've got it.  Basicaly
eexec is an encryption algorthym that uses a linear congruent random number
and uses the byte of data and XOR's them together, then uses the incoming
data to compute the next random number.

you might try this

nclude "stdio.h"
 
 
/*
	routine takes an encrypted eexec file and creates a
	decrypted  file.  
By Woody Baker
*/
 
FILE *infile,*outfile;
 
main(argc,argv)
char *argv[];
int argc;
{
int first =4;
int state=0xD971;
int c;
char decrptd;
 
	if(argc !=3)
		{
		printf("usage:  decrpt infile outfile\n");
		exit(0);
		};
	infile=fopen(argv[1],"rb");
	outfile=fopen(argv[2],"wb");
	
	while(fscanf(infile,"%2x",&c)>0)
		{
			decrptd= c ^ (state >>8);
			if(first !=0)
				{
				first--;
				}
			else
				{	
				fputc(decrptd,outfile);
				}
			state=state + c;
			state=state * 0xCE6D;
			state=state + 0x58BF;
		}
	fclose(infile);
	fclose(outfile);	
}				
		
I think this is the working version that I use.  
Hope this helps.
Cheers
Woody