'Verschlüsseln
    Private Sub Button1_Click([...]) Handles Button1.Click
 
        Dim RdM As New RijndaelManaged
 
        Dim MD5 As New MD5CryptoServiceProvider
        Dim Key() As Byte = MD5.ComputeHash(Encoding.UTF8.GetBytes("12345678"))
 
        MD5.Clear()
        RdM.Key = Key
        RdM.GenerateIV()
 
        Dim IV() As Byte = RdM.IV
 
        Dim FStream As New FileStream("D:\test.test", FileMode.Create)
        Dim CStream As New CryptoStream(FStream, RdM.CreateEncryptor, _
          CryptoStreamMode.Write)
        Dim WStream As New StreamWriter(CStream)
 
        FStream.Write(IV, 0, IV.Length)
 
        WStream.WriteLine(TextBox1.Text)
 
        CStream.FlushFinalBlock()
 
        WStream.Close()
        CStream.Close()
        FStream.Close()
 
        RdM.Clear()
 
    End Sub
 
    'Entschlüsseln
    Private Sub Button2_Click([...]) Handles Button2.Click
 
        Dim RdM As New RijndaelManaged
        Dim RdIVLength As Integer = 16
        Dim MD5 As New MD5CryptoServiceProvider
        Dim Key() As Byte = MD5.ComputeHash(Encoding.UTF8.GetBytes("12345678"))
 
        MD5.Clear()
 
        Dim FStream As New FileStream("D:\test.test", FileMode.Open)
        Dim IV(15) As Byte
 
        FStream.Read(IV, 0, RdIVLength)
        RdM.IV = IV
        RdM.Key = Key
 
        Dim CStream As New CryptoStream(FStream, RdM.CreateDecryptor, _
          CryptoStreamMode.Read)
        Dim RStream As New StreamReader(CStream)
 
        TextBox2.Text = RStream.ReadLine()
 
        RStream.Close()
        CStream.Close()
        FStream.Close()
 
        RdM.Clear()
 
    End Sub