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Software Vault: The Gold Collection
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Software Vault - The Gold Collection (American Databankers) (1993).ISO
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cdr12
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toplib50.zip
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HUM-UNP.ZIP
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HUMANS.TOP
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Text File
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1993-01-17
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2KB
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42 lines
Another fine Crack From -TOP-
TOP is Tired of Protection how about you?
Unprotect for HUMANS!
**********************************
Documentation kind of check
**********************************
use the enclosed loader named CRACK.EXE
The method involved:
The assembly listing is enclosed for those interested. The
program could not be directly cracked due to the encryption scheme that
hid the necessary areas. However, I thought I would take you through
what I did go through in order to crack this one. The Mage called me
and we were looking over this one. The doc check appears early in the
game and it was not hard to follow through. I watched the program
manipulate my answer and store it in the BP register. However, now you
reached what looked like an infinite loop - a jump to the previous
statement. This did not make sense but when you ran the program, the
program would continue as it should (it crashed). That means it was
not an infinite loop. The only thing that could get out of such a loop
would be an interrupt. So, using the VECS command on soft-ice (this
will tell you all the interrupt vectors), I noticed that Interrupts
0-4,8, and 63 were being used by the the HUMANS program. INT 8 is the
system timer and will activate around 16-17 times per second. This had
to be what they were using to get out as it was the most reliable to
use. Placing a break point on INT 8 quickly brought me to a new section
of code. Watching BP (remember from earlier?) carefully, I found where
it was moved to DX and then compared. This was it! Changing the
compare to CMP BX,BX solved the game nicely. Unfortunately the code
could not be directly done and so hence the loader.
Oh, one other interesting trick the enemy programmers used--if you
don't crack it correctly the program will show you a series fo scenes
as if the program is going to run but, it crashes!
ENJOY!!
The Mad Doctor
-TOP- crack.