private exe protector unpacking?

[0xall0c]

so i think this is doing something like xoring the first byte at that address where the exception is occuring, and as because registration is bypassed by xoring but our licence is still invalid so i get exception?

also this is wrapped by a loop and later one more loop to decrypt another function!!
dont know how i can validate the licence keys!

here:

push ebx
mov ebx,dword ptr ds:[eax]
xor ebx,dword ptr ds:[edx]
mov dword ptr ds:[ecx],ebx
mov ebx,dword ptr ds:[eax+4]
xor ebx,dword ptr ds:[edx+4]
mov dword ptr ds:[ecx+4],ebx
mov ebx,dword ptr ds:[eax+8]
xor ebx,dword ptr ds:[edx+8]
mov dword ptr ds:[ecx+8],ebx
mov eax,dword ptr ds:[eax+C]
xor eax,dword ptr ds:[edx+C]
mov dword ptr ds:[ecx+C],eax
pop ebx
ret