hi everyone!
this is my encryption routine (using standard call) in x86 Assembler


push ebp
mov ebp,esp
mov eax, [ebp+8]
mov ecx, [ebp+12]

push eax
and eax,0xAA
not al
mov edx,eax
pop eax
and eax,0x55
xor ecx,edx
xor ecx,eax
rol cl,1
rol cl,1
mov eax,ecx

sub al,0x20
pop ebp

all im trying to do now is Reverse the "encrypt" Algorithms Effect (need to create a DECRYPT routine)
if anyone can help me, it would be much appreciated!
thanks x

ps..if you need any more information, let me know .

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Not sure which of the four people from hallam you are but u might wanna be more careful when asking for answers in forums

This appears to be, at first blush, a simple xor substitution/rotation algorithm. Simple stuff. You solve it... If this is from commercial software, I have to think there is more to it than this, unless they are trying for "security by obscurity" - the key is in the "key". If you have the key, and know the algorithm to transform the plain-text, decryption is (at least for symmetric keys) trivial. Read Bruce Schneier's book "Applied Cryptography" if you are interested in this stuff.

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