copymemory VB6/VBA to VB.net Arithmetic operation resulted in an overflow

Hey all I am trying to figure out how to get the following to work or replace in order to make work:

Module1:

    Private oTest                   As Class1
    Private InitDone                As Boolean
    Private Map1(0 To 63)           As Byte
    Private Map2(0 To 127)          As Byte

    #If VBA7 Then
      Public Declare PtrSafe Function GetSystemMetrics Lib "user32" (ByVal nIndex As Long) As Long
    #Else
      Public Declare Function GetSystemMetrics Lib "user32" (ByVal nIndex As Long) As Long
    #End If

    Private Declare Sub CopyMemoryByref Lib "Kernel32.dll" & _
                        Alias "RtlMoveMemory" (ByRef dest As Integer, ByRef & _
                        source As Integer, ByVal numBytes As Integer)
      
    Private Declare Function VarPtr Lib "vb40032.dll" & _
                             Alias "VarPtr" (lpObject As Integer) As Long

    Public Function EncryptData(ByRef bytMessage() As Byte, ByRef bytPassword() As Byte) As Byte()
    		Dim bytKey(31) As Byte
    		Dim bytIn() As Byte
    		Dim bytOut() As Byte
    		Dim bytTemp(31) As Byte
    		Dim lCount, lLength As Integer
    		Dim lEncodedLength, lPosition As Integer
    		Dim bytLen(3) As Byte
    		
    		If Not IsInitialized(bytMessage) Then Exit Function
    		If Not IsInitialized(bytPassword) Then Exit Function
    		
    		For lCount = 0 To UBound(bytPassword)
    			bytKey(lCount) = bytPassword(lCount) : If lCount = 31 Then Exit For
    		Next lCount
    		
    		gentables()
    		gkey(8, 8, bytKey)
    		lLength = UBound(bytMessage) + 1 : lEncodedLength = lLength + 4
    		
    		If lEncodedLength Mod 32 <> 0 Then lEncodedLength = lEncodedLength + 32 - (lEncodedLength Mod 32)
    		
    		ReDim bytIn(lEncodedLength - 1) : ReDim bytOut(lEncodedLength - 1)
    
            Try
                CopyMemory(VarPtr(bytIn(0)), VarPtr(lLength), 4)
            Catch ex As Exception
                MessageBox.Show(ex.Message)
            End Try
        
            For lCount = 0 To lEncodedLength - 1 Step 32
    		   CopyMemory(VarPtr(bytTemp(0)), VarPtr(bytIn(lCount)), 32)
    		   Encrypt(bytTemp)
    		   CopyMemory(VarPtr(bytOut(lCount)), VarPtr(bytTemp(0)), 32)
    		Next lCount
    End Function

Select allOpen in new window

UserForm:

    Private Sub Command1_Click(ByVal eventSender As System.Object, ByVal eventArgs As System.EventArgs) Handles Command1.Click
		Dim sTemp, sPassword As String
		
		sTemp = "this is a test"
        Debug.Print("       To encrypt: " & sTemp)

        sPassword = "blk@vjdii:5@fAB5"
        Debug.Print(StrReverse(sPassword))

        sPassword = Str2Hex(strEncrypt(sPassword, StrReverse(sPassword)))
        Debug.Print("       Secret key: " & sPassword)

        sTemp = Str2Hex(strEncrypt(sTemp, sPassword))
        Debug.Print("          Encrypt: " & sTemp)
		
		sTemp = Base64EncodeString(sTemp)
        Debug.Print("Encrypt w/ Base64: " & sTemp)

        sTemp = Base64DecodeString(sTemp)
		Debug.Print("Decrypt w/ Base64: " & sTemp)

        sTemp = Hex2Str(sTemp)
        Debug.Print("          Decrypt: " & strDecrypt(sTemp, sPassword))
	End Sub

Select allOpen in new window

This code works just fine when using it within the VBA excel code. This is the VB6 output:

To encrypt: this is a test
Secret key: F050C1C2B61E8DCC349DC498D9993F8D11330F12D9E0071B4B83D172FEBE5AED
Encrypt: F899ABA853D21B20F889CFD18BB42C472187B4E1CF613139370313DFD8A492DE
Encrypt w/ Base64:
Rjg5OUFCQTg1M0QyMUIyMEY4ODlDRkQxOEJCNDJDNDcyMTg3QjRFMUNGNjEzMTM5MzcwMzEzREZEOEE
0OTJERQ==
Decrypt w/ Base64: F899ABA853D21B20F889CFD18BB42C472187B4E1CF613139370313DFD8A492DE
Decrypt: this is a test

However, when converting it over to .net I get the error of:

Arithmetic operation resulted in an overflow.

on the line CopyMemory(VarPtr(bytIn(0)), VarPtr(lLength), 4).

How can I re-write this in order for it to work so both VB.net and VB6 can share the code base in order to encrypt/decrypt string messages back and forth?