[help] semplice crypta stringhe

[kerberos5]

Ciao sto cercando di creare un semplicissimo tool per cifrare e decifrare stringhe con xor, ma la funzione che voglio utilizzare è codata in shellcode e vorrei cercare di integrarla nel progetto in vb.net infatti il mio scopo è quello di capire come adattare funzioni natie (originariamente questa funzione xor è stata codata per vb6) tipo VarPtr o StrPtr in vb.NET ecco il codice

1 form
3 textbox
2 bottoni
1 modulo

nella form

Public Class frmMain
  
    Private Sub btnEnc_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnEnc.Click
        'encrypt
        Dim chiave As String = "aonyregpnxmtxppm"
        txtEnc.Text = mXOR.ASMXORString(txtClear.Text, chiave)
    End Sub

    Private Sub btnDec_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDec.Click
        'decrypt
        Dim chiave As String = "aonyregpnxmtxppm"
        txtDec.Text = mXOR.ASMXORString(txtEnc.Text, chiave)
    End Sub
End Class

nel modulo

Imports System.Runtime.InteropServices
Imports System.Text
Module mXOR
    Private Declare Function CallWindowProc Lib "user32" Alias "CallWindowProcW" (ByVal ptrMC As Long, ByVal P1 As Long, ByVal P2 As Long, ByVal P3 As Long, ByVal P4 As Long) As Long
    Private MyByteXor(93) As Byte ' Byte array (hold the ASM ShellCode)
    Private ptrMC As Long 'Byte array Pointer Store Value

    Public Function ASMXORString(ByVal Str As String, ByVal Password As String) As String
        Call LeggiCodiceMasm32()
        Call CallWindowProc(ptrMC, Marshal.PtrToStringAuto(Str), Len(Str), Marshal.PtrToStringAuto(Password), Len(Password))
        ASMXORString = Str
    End Function

    Public Sub ASMXORByte(ByVal ByteA() As Byte, ByVal Password As String)
        Call LeggiCodiceMasm32()
        Call CallWindowProc(ptrMC, VarPtr(ByteA(0)), UBound(ByteA), Marshal.PtrToStringAuto(Password), Len(Password))
    End Sub


    Sub LeggiCodiceMasm32()
        MyByteXor(0) = 85
        MyByteXor(1) = 137
        MyByteXor(2) = 229
        MyByteXor(3) = 83
        MyByteXor(4) = 86
        MyByteXor(5) = 87
        MyByteXor(6) = 139
        MyByteXor(7) = 69
        MyByteXor(8) = 12
        MyByteXor(9) = 133
        MyByteXor(10) = 192
        MyByteXor(11) = 116
        MyByteXor(12) = 70
        MyByteXor(13) = 139
        MyByteXor(14) = 69
        MyByteXor(15) = 20
        MyByteXor(16) = 133
        MyByteXor(17) = 192
        MyByteXor(18) = 116
        MyByteXor(19) = 63
        MyByteXor(20) = 139
        MyByteXor(21) = 77
        MyByteXor(22) = 12
        MyByteXor(23) = 209
        MyByteXor(24) = 225
        MyByteXor(25) = 139
        MyByteXor(26) = 85
        MyByteXor(27) = 8
        MyByteXor(28) = 1
        MyByteXor(29) = 202
        MyByteXor(30) = 247
        MyByteXor(31) = 217
        MyByteXor(32) = 139
        MyByteXor(33) = 93
        MyByteXor(34) = 20
        MyByteXor(35) = 209
        MyByteXor(36) = 227
        MyByteXor(37) = 139
        MyByteXor(38) = 69
        MyByteXor(39) = 16
        MyByteXor(40) = 1
        MyByteXor(41) = 216
        MyByteXor(42) = 137
        MyByteXor(43) = 69
        MyByteXor(44) = 16
        MyByteXor(45) = 247
        MyByteXor(46) = 219
        MyByteXor(47) = 137
        MyByteXor(48) = 93
        MyByteXor(49) = 20
        MyByteXor(50) = 139
        MyByteXor(51) = 4
        MyByteXor(52) = 10
        MyByteXor(53) = 3
        MyByteXor(54) = 93
        MyByteXor(55) = 16
        MyByteXor(56) = 50
        MyByteXor(57) = 3
        MyByteXor(58) = 43
        MyByteXor(59) = 93
        MyByteXor(60) = 16
        MyByteXor(61) = 129
        MyByteXor(62) = 195
        MyByteXor(63) = 2
        MyByteXor(64) = 0
        MyByteXor(65) = 0
        MyByteXor(66) = 0
        MyByteXor(67) = 117
        MyByteXor(68) = 3
        MyByteXor(69) = 139
        MyByteXor(70) = 93
        MyByteXor(71) = 20
        MyByteXor(72) = 137
        MyByteXor(73) = 4
        MyByteXor(74) = 10
        MyByteXor(75) = 129
        MyByteXor(76) = 193
        MyByteXor(77) = 2
        MyByteXor(78) = 0
        MyByteXor(79) = 0
        MyByteXor(80) = 0
        MyByteXor(81) = 117
        MyByteXor(82) = 223
        MyByteXor(83) = 49
        MyByteXor(84) = 192
        MyByteXor(85) = 95
        MyByteXor(86) = 94
        MyByteXor(87) = 91
        MyByteXor(88) = 137
        MyByteXor(89) = 236
        MyByteXor(90) = 93
        MyByteXor(91) = 194
        MyByteXor(92) = 16
        MyByteXor(93) = 0
        ptrMC = VarPtr(MyByteXor(0))

    End Sub
    ' a delegate that can point to the VarPtrCallback method
    Private Delegate Function VarPtrCallbackDelegate( _
       ByVal address As Integer, ByVal unused1 As Integer, _
       ByVal unused2 As Integer, ByVal unused3 As Integer) As Integer

    ' two aliases for the CallWindowProcA Windows API method
    ' notice that 2nd argument is passed by-reference
    Private Declare Function CallWindowProc Lib "user32" _
       Alias "CallWindowProcA" _
       (ByVal wndProc As VarPtrCallbackDelegate, ByRef var As Short, _
       ByVal unused1 As Integer, ByVal unused2 As Integer, _
       ByVal unused3 As Integer) As Integer

    Private Declare Function CallWindowProc Lib "user32" _
       Alias "CallWindowProcA" _
       (ByVal wndProc As VarPtrCallbackDelegate, ByRef var As Integer, _
       ByVal unused1 As Integer, ByVal unused2 As Integer, _
       ByVal unused3 As Integer) As Integer
    ' ...add more overload to support other data types...

    ' the method that is indirectly executed when calling CallVarPtrSupport
    ' notice that 1st argument is declared by-value (this is the
    ' argument that receives the 2nd value passed to CallVarPtrSupport)
    Private Function VarPtrCallback(ByVal address As Integer, _
          ByVal unused1 As Integer, ByVal unused2 As Integer, _
          ByVal unused3 As Integer) As Integer
        Return address
    End Function

    ' two overloads of VarPtr
    Public Function VarPtr(ByRef var As Short) As Integer
        Return CallWindowProc(AddressOf VarPtrCallback, var, 0, 0, 0)
    End Function

End Module

Navigando qui e li ho letto che StrPtr andrebbe gestita con la classe Marshal ma non ci riesco mi restituisce questo errore:
error.jpg

Scusate non ho messo tag nel titolo linguaggio vb.NET ide Visual Studio 2008