Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles MyBase.Load
        Dim sb() As Byte = Encrypt("Some data", "secret")
        Dim s1 As String = DeCrypt(sb, "secret")
    End Sub
 
    Function Encrypt(ByVal data As String, ByVal key As String) As Byte()
        Dim Mymemorystream As MemoryStream = New MemoryStream
        Dim DES As DESCryptoServiceProvider = New DESCryptoServiceProvider
        DES.Key = GetBytesfromString(key, 8)
        DES.IV = DES.Key
        Dim MyCryptostream As CryptoStream = New CryptoStream(Mymemorystream, _
          DES.CreateEncryptor(), CryptoStreamMode.Write)
        Dim writer As StreamWriter = New StreamWriter(MyCryptostream)
        writer.Write(data)
        writer.Flush()
        MyCryptostream.FlushFinalBlock()
        Dim cryptData() As Byte = Mymemorystream.ToArray()
        writer.Close()
        MyCryptostream.Close()
        Mymemorystream.Close()
        Return cryptData
    End Function
 
    Function DeCrypt(ByVal data() As Byte, ByVal key As String) As String
        Dim Mymemorystream As New MemoryStream(data)
        Dim DES As DESCryptoServiceProvider = New DESCryptoServiceProvider
        DES.Key = GetBytesfromString(key, 8)
        DES.IV = DES.Key
        Dim MyCryptostream As CryptoStream = New CryptoStream(Mymemorystream, _
          DES.CreateDecryptor(), CryptoStreamMode.Read)
        Dim reader As StreamReader = New StreamReader(MyCryptostream)
        Dim CryptData As String = reader.ReadToEnd  'auslesen des 
        ' Verschlüsselten Wertes aus Speicher
        reader.Close()
        MyCryptostream.Close()
        Mymemorystream.Close()
        Return CryptData
    End Function
 
    Public Function GetBytesfromString(ByVal pw As String, ByVal l As Integer) _
      As Byte()
        Dim pwdb As New PasswordDeriveBytes(pw, Nothing)
        Return pwdb.GetBytes(l)
    End Function