Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button1.Click
        Me.TextBox1.Text = MixString.MixString(Me.TextBox1.Text)
    End Sub
 
Public Class MixString
    Public Shared Function MixString(ByVal s As String)
        Dim t As String = ""
        If s.Length < 2 Then Return s
        Do Until s <> t And t.Length = s.Length
            t = MixString_Sub(s)
        Loop
        Return t
    End Function
    Private Shared Function MixString_Sub(ByVal s As String) As String
        Dim s_, t As String : s_ = ""
        Dim z, a(s.Length), i As Int32
        Do Until s_.Length = s.Length
            z = MakeRndNumber(s.Length, a)
            a(i) = z
            i += 1
            t = Mid(s, z, 1)
            s_ &= t
        Loop
        Return s_
    End Function
    Private Shared Function MakeRndNumber(ByVal MaxNumber As Int32, ByVal _
      NotNumbers As Int32()) As Int32
        Dim z As Int32
        Randomize()
        If NotNumbers Is Nothing Then
            Do Until z < (MaxNumber + 1) And z > 0
                z = CInt(Int((MaxNumber * Rnd()) + 1))
            Loop
        Else
            Do Until z < (MaxNumber + 1) And NotNumbers.IndexOf(NotNumbers, z) _
              = -1 And z > 0
                z = CInt(Int((MaxNumber * Rnd()) + 1))
            Loop
        End If
        Return z
    End Function
End Class