Dec 092017
Remove registration info from stacker v2.0.
File STKRUNP.ZIP from The Programmer’s Corner in
Category Unprotects for Games and Such
Remove registration info from stacker v2.0.
File Name File Size Zip Size Zip Type
STACKER.TXT 3057 1340 deflated

Download File STKRUNP.ZIP Here

Contents of the STACKER.TXT file


This will work on the file dated 10-23-91 and is 40667 bytes long.
It may or may not work on other versions. You may adapt it and try it on
other versions of the file (see DISCUSSION for info).

1) Use Norton Utility or a similar hex/text editor and go to file offset
99C7 hex.
It should be: 32 24 46 E2 F9 0A E4 C3
Change to : B4 00

2) Go to file offset 3CF4 hex
It should be: A5 98 9A 9C A6 A7 ..........ETC.
Change to : 53 53 53 53 53 53 ...........

The number of "53"'s you add here is important. 18+(total # characters in
the encoded name). For example if the registrants name is
Gomer Q. Pyle you should add 18+13=31 "53"'s at this location. Adding
more may overwrite code and adding less will not completely erase the
name. If you are not sure, add less, check the results, then adjust.


Stepping through the COM file and changing the call (CALL 4A2E) to display the
registration information does not work. Depending on how you do it (with NOP
versus call redirection) you will get no effect or a file checkum error on
execution. What happened to me (not necessarily all the time I tried it)
was that the com file rewrote my NOP's back to CALL 4A2E when stacker was run.
No, I didn't screw up the write and Yes, I'm sure it was the same
that I just modified. If you trace through you will discover that:

1) File checkum=true involves having 00h in AH at the end of
decoding. Inserting B4 00 (translates to MOV AH,00) at offset 99C7
gets rid of that problem.

2) The name (as well as the rest of the program) is encoded by adding
CDh to each byte stored past the decode call (I forget what the
CALL is, sorry). Therefore a space (20h) is encoded as 53h if you
drop the preceding F's after the calculation. Obviously this is
why the name is not visible with a hex editor (neither is any
other prompt, such as "Registered to:" for that matter).
The "Registered to: XXXXXXXX" is stored at file offset 3CF4.
Writing 53h over this data in effect writes 20h (or an empty space)
over the registrants name.



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 December 9, 2017  Add comments

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