Subj : Re: Doorgame cracking
To   : esc
From : Bugz
Date : Fri Feb 03 2023 02:10 pm

-=> esc wrote to Bugz <=-

 es> Appreciate this - hearing which tools are useful at this early stage is
 es> very helpful. I don't see IDA's ability to work on 16 bit DOS binaries
 es> with the free version...is there an older version somewhere floating
 es> aroudn that you know of that I can use without paying them thousands of
 es> dollars for a license?

I bought my IDA license back in 2001.  I think it was around $250.  My 
old version even runs under DOS (using the dos4gw protect mode), so it makes
use of all the memory available under DOS.

The prices have gone up, but they do even more today.  (Well, they don't
support DOS!  Ah, well, such is progress...)

 Bu> My goto tool is TD (Turbo Debugger) in dosbox.

 es> Sweet. Ok. I'll track this down in that case. Any specific version? Is
 es> it easy to get installed and set up for doing this work?

I'm using 3.1.  They should be about the same.  You probably could use DOS's
debug for that matter, but it's not very pretty.  You'd have to hit extra
keys to see what TD shows you in an instant.  And debug's output would be
with program output as well.  That really won't look good.

 Bu> As my time permits, I'll see what I can come up with.

I've made some progress on this.  I have a very short intro to asm.
(Better can be found on the web, I'm sure.)  A section on working with IDA, 
and working with Turbo Debugger.

I can put up what I've got so far somewhere out there.  I'd love feedback
if I could.  It's always difficult to cover something complex, when you've
been doing it for years.  What seems "obvious" to me might not be.  :)

I'm hoping to finish this weekend.

* I wanted to cover more about diving deeper into the sample disassembly.
    As far as possibly making a keygen for my example.
* Other ways of doing things.  I'd like to make an example that brute forces
my example.

Take care,
bugz

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