Dim str As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
Dim r As New Random
Dim sb As New StringBuilder
For i As Integer = 1 To 20
Dim idx As Integer = r.Next(0, 35)
sb.Append(str.Substring(idx, 1))
Next
Me.Text = sb.ToString