rigsby

I personally would love to be able to read and understand the codes and stuff. After this hit thing is all over and done with, maybe the fellas who know this stuff, could do a bit of a tutorial on how the do flash file. I think there would be a lot of students on here who would be really grateful.

ATB, Rigsby.

djmagic

i agree
i have some time on my hands and would love to try....

rigsby

Looks like we will have to tempt one of the boffins to teach us djmagic......though I could understand their reluctance to do it. I wouldn't fancy trying to teach me how to write a flash image.....me missus' says she pitys the fella who try to attempt to teach me anything!!

slain

As far as I can tell, it'll be two lines added/changed in prune.asm, which will be XORing (eor) values stored a couple of the rX registers. Then you compile, with your two provider lines commented out too (set to ex-c&w by default).

It's more about knowing your way around the source for a fix like this, I'd think... and being able to decipher the EMM, but there are tools around to do that already.

djmagic

wow that seems like i good start i will research a little more
thanks

rigsby

Erm.....thanks for that slain....I'm already struggling..lol....I'm thinking I need to refer to the first post in this thread, as a starting point?

ATB Rigsby.

slain

Yep, the EMM has already been decoded in the original post. In effect it's all about changing code in a routine to handle that EMM. The current handler nearly does it right, just doesn't XOR those two bytes that fez_786's post pointed out. Add/modify two lines to perform those XORS on the correct registers, and it should be fine. I think?

Bare in mind I'm not entirely sure myself, and could do with some clarification as well.

rigsby

Cheers slain thanks for replying....and at least trying to teach a fool like me. I will try later to understrand what you have told me.

Thanks again,
Rigbsy.

cydine_

You're getting there.

At $94 it's loading the value of X into A.
At $95 it's xoring A against the value at $B1

The problem is that the value of X is not what it is meant to be.

At $82, the correct value - #$79 is loaded into A. Somewhere in the following subroutines this value should be transferred to X. This is where the emu breaks down.

So when you get to $94, the value of X is not #$79 as it should be. Therefore the result of the xor is incorrect and so is the resulting key.

The fix - load X with the corrrect value (found at $83) before the xoring occurs and the correct key will be produced

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zeroprobe

Where do we add the new instructions is it in the prune.asm of the chaos source code?