As i commmented vb has its own set of functions the fuction you have to look for in the 3rd crackme are rtcMidCharVar() vbastrvarval() , rtcAnsiValueBstr() _vbavarmul() the algo loops over the name characters adds a constant to each multiplies the result with another variable and adds up all of them that is your serial if you give the right serial you get a msgbox with password **axxxxxxo** a simple keygen in powershell can look like $b =0;$a = SOMECONSTANT;@('d','u','g','g') | % { $c= (([int][char]$_ + SOMEOTHERCONSTANT) * AVARIABLE);($b+=$c) };$b [![enter image description here][1]][1] edit , vb does not use registers mostly it uses a [VARIANT][2] structure for almost all functions and uses stack if you use windbg you can take a look at the structure with **dt ole32!VARIANT** basically it is a ten byte long structure consisting of an union 0:000> dt -v ole32!Variant struct tagVARIANT, 50 elements, 0x10 bytes the first member vt (SHORT int2b) indicates the variant type the next 3 SHORTS are reserved the value at 0x08 is to deciphered based on the value of vt member the member at 0x0c is pRecInfo the member at 0x10 is tagDec an array now that part is clear the function __vbaVarMul Takes three Arguments of type VARIANT the first is the result the second is multiplier the third is multiplicand here is a redacted windbg output for char 'd' 0:000> ? poi(@esp) Evaluate expression: 1241928 = 0012f348 0:000> ? poi(@esp+4) Evaluate expression: 1241944 = 0012f358 0:000> ? poi(@esp+8) Evaluate expression: 1241880 = 0012f318 0:000> dt ole32!Variant vt poi(@esp) +0x000 vt : 0 <---- vb NULL / v_EMPTY 0:000> dt ole32!Variant vt poi(@esp+4) +0x000 vt : 3 <-------vbLong 0:000> dt ole32!Variant vt poi(@esp+8) +0x000 vt : 2 <-----vbInt 0:000> .enable_long_status 1 0:000> dt ole32!Variant lVal poi(@esp) +0x008 lVal : 0x12f3f0 0:000> dt ole32!Variant lVal poi(@esp+4) +0x008 lVal : 0xxx 0:000> dt ole32!Variant lVal poi(@esp+8) +0x008 lVal : 0xxxx 0:000> ? 'd' + xxx Evaluate expression: xxxx = 00000xxx [1]: https://i.sstatic.net/YcOlq.png [2]: https://msdn.microsoft.com/en-us/library/windows/desktop/ms221627(v=vs.85).aspx