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Path: utzoo!utcsrgv!dudek
From: dudek@utcsrgv.UUCP (Gregory Dudek)
Newsgroups: net.micro.apple
Subject: Re: Disk Protection (problems)#
Message-ID: <3511@utcsrgv.UUCP>
Date: Mon, 12-Mar-84 17:08:07 EST
Article-I.D.: utcsrgv.3511
Posted: Mon Mar 12 17:08:07 1984
Date-Received: Mon, 12-Mar-84 17:26:51 EST
References: <575@ihuxn.UUCP>
Organization: CSRG, University of Toronto
Lines: 31

It looks to me like your disk "backup" method will only work
on the simper protection schemes.  
   For those of you who missed the lead-in article, it outlined
saving a memory image of a "locked" program by using the built-in
tape read/write code.  The method for getting control of the Apple
was to re-route the RESET vector via the language card so that
you could use the monitor to capture the program.
At least, this was my understanding.
   The problem seems to be that:
   a) most well protected software uses a multi-stage boot (I
      would still call this "single disk access" loading), and
      the first stage often disables the language card.
   b) Some protected software keeps code "behind" the keyboard
      buffer so that typing things destroys it.
      (i.e. when you trys to type in the tape save command.)

   One method the "crackers" use to deal with software that 
does these "neat" things is called "boot trace cracking".  This
involves copying the bootstrap ROM code (at c600) and making it
branch back to the monitor after the first phase of boot, instead
of to the loaded code (at 0x0800).  This procedure is then
repeated for each phase of the boot.
   To make this difficult for them, intermediate sections of the
code can be loaded at the monitors keyboard in buffer, or into
the screen buffer so then then control returns to the monitor, it
automatically erases the offending code.
   Gregory Dudek
   {cornell,decvax,ihnp4,linus,utzoo,uw-beaver}!utcsrgv!dudek
-- 
   Gregory Dudek
   {cornell,decvax,ihnp4,linus,utzoo,uw-beaver}!utcsrgv!dudek