Generacion de Alfanumerico Aleatorio

sub aleatorio()

        Dim cod_ale As String
        Dim Letters As New List(Of Integer)

        'codigos ASCII numericos
        For i As Integer = 48 To 57
            Letters.Add(i)
        Next

        'codigos ASCII letras minusculas
     
        For i As Integer = 97 To 122
        Letters.Add(i)
        Next
       
       'codigos ASCII letras mayusculas
       
        For i As Integer = 65 To 90
        Letters.Add(i)
        Next
       
      'colocamos la cantidad de carracteres para nuestro autogenerado (6)
       
        Dim Rnd As New Random
        Dim SB As New System.Text.StringBuilder
        Dim Temp As Integer

        For count As Integer = 1 To 6
            Temp = Rnd.Next(0, Letters.Count)
            SB.Append(Chr(Letters(Temp)))
        Next

        cod_ale = SB.ToString

end sub