Скачать Jump Tracer

18.09.1996
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Jump Tracer

Well, I don't feel like writing complete dox right now - I'll do it after I add some missing features, such as making .CRK files, to Jump Tracer.

I'll just try to explain the Jump Tracer's cracking method now. The main idea is to compare two or more different ways of program's execution and find where it branches. After that we can change or remove the condition so that the program will always run the desired way.

For example, this can be used to remove copy protection (this version of Jump Tracer uses only some simple methods to fool anti-debugging code, so it may not always work properly). To do it you need to trace the program to crack at least twice - the first time with the required keydisk, plug in LPT port, entering the correct password, etc.; and the second time without the key.

Also, you can crack games (Jump Tracer is especially useful when cracking things like making it possible to move through walls, that couldn't be done with Player's Tool or Game Wizard), remove shareware delays (it's done by enabling saving of jumps being executed for different periods of time - the first time while in delay loop and the second slightly before the loop ends) and finally you can simply change program's behavior (for example disable some annoying functions).

Usage Example

Let's suppose we need to disable the F1 key in Volcov Commander. ;) BTW, I'm still using its beta version because the 4.0 release does not support searching for hex bytes using Alt-F7. ;(

Run Jump Tracer:

jmptrace c:\vc\vc.com

Use to turn saving on/off while tracing, left to abort Trace, Quit? T

Enter program parameters:

[Press , , , , , ]

Please, identify this state as: 1st, 2nd, Nothing? 1

You've saved 1 dump by now; at least 2 different dumps are required to crack

Trace, Quit? T

Enter program parameters:

[Press , , , ]

Please, identify this state as: 1st, 2nd, Nothing? 2

You've saved 2 dumps by now; you can compare them

Trace, Compare, Quit? C

Smartly comparing and filtering...

?: Internal offset 364D: ? N

[Some other lines may appear here if, for example, more than a second passed while tracing and clock in VC redrawn. If so, make more than 2 dumps to find the exact offset]

Return, Display? D

The program will now be traced once more, you may have to enable saving for a long time to find the desired jump

Enter offset: 364D

Enter program parameters:

[Press , , , ]

PSP+0299:AFA6: 75 06 E8 CB C7 58 EB F1 44 44 C3 55 8B EC 83 EC
Use 1st state: PATCH NOT AVAILABLE
Use 2nd state: EB

Please, identify this state as: 1st, 2nd, Nothing? N

Return, Display? R

You've saved 2 dumps by now; you can compare them

Trace, Compare, Quit? Q

Here we got a pattern to search for in VC.COM - do it using VC itself and change the first pattern's byte value to EB. If you patch the first two bytes with 90 90 instead, you won't be able to exit help. ;) However, this state is unstable - that's why Jump Tracer said that such patch is not available. The same about question mark in the comparison result.

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Скачать Jump Tracer

Jump Tracer