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flat assembler > Examples and Tutorials > ultimate xor use

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Joined: 08 Jan 2018
Posts: 139
; standard and basic xor encryption
BASE = 2525h

mov edx,BASE
xor edx,25h ; just any number to encrypt
; result is 2500h
; now to retrieve the encrypted number back
; xor base by result
xor edx,BASE ; remember edx have 2500h from last xor operation
; now edx have the original number which is 25h    

; another use of xor i dont know what to call it but it can be useful to store qword values and write them later to memory location
HIGH_QWORD = 23456789h
; FULL_QWORD = 23456789ABCDEF10h

mov edx,LOW_QWORD ; store the low 32bit value
xor edx,HIGH_QWORD ; we need the result
; result is 88888899h ; the KEY
mov eax,88888899h ; store it in eax for later use

; now to get the HIGH_QWORD, xor KEY by LOW_QWORD
xor edx,LOW_QWORD ; remember edx have 88888899h and being xored by ABCDEF10 which is low qword
; the result is 23456789h = high qword

; to get the LOW_QWORD xor KEY by the HIGH_QWORD
xor edx,eax ; = eax is our key 88888899h, edx = high qword
; result is 0ABCDEF10 = low qword    

Asm For Wise Humans
Post 26 Jul 2018, 16:45
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Joined: 12 Oct 2018
Posts: 30
It can be used to flip bits
xor al,1 ; Flips the first bit    

Can we get another unique xor usage/trick by the next person? We want this thread to grow larger with unique answers. Forum users are encouraged to participate!

The king auto-generates two things to degrade dangerous artists and intellectuals. The King reserves the right to be king and has made the culprits in advance. Half of the time or more, they are auto-generated.
Post 20 Oct 2018, 18:49
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