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Ali.Z



Joined: 08 Jan 2018
Posts: 687
Ali.Z 09 Jun 2024, 11:29
is there any way to post process a block of code or data or both in fasm1?

say after assembling a block instructions i want to xor every byte with a key.

i dont mind incremental xor too.

the goal is to rely on fasm instead of external tool to xor that block of bytes.

if important my xor key is 87h or 135d.

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Asm For Wise Humans
Post 09 Jun 2024, 11:29
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 20215
Location: In your JS exploiting you and your system
revolution 09 Jun 2024, 11:57
Code:
while % <= $-$$
 load x byte from $$+%-1
 store byte x xor the_key to $$+%-1
end while    
Post 09 Jun 2024, 11:57
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Ali.Z



Joined: 08 Jan 2018
Posts: 687
Ali.Z 09 Jun 2024, 12:49
i tried different ways, but i dont seem to understand how to use it. Sad

first thing i replaced the_key with 87h, then i tried to place instructions before end while, but nothing happens. (also tried other ways)

would you please provide an example? thanks.

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Asm For Wise Humans
Post 09 Jun 2024, 12:49
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Tomasz Grysztar



Joined: 16 Jun 2003
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Location: Kraków, Poland
Tomasz Grysztar 09 Jun 2024, 14:35
See https://board.flatassembler.net/topic.php?t=2126 for a more thorough example.
Post 09 Jun 2024, 14:35
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Ali.Z



Joined: 08 Jan 2018
Posts: 687
Ali.Z 09 Jun 2024, 15:23
thank you.

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Asm For Wise Humans
Post 09 Jun 2024, 15:23
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