Dim FF% = FreeFile()
    FileOpen(FF, "C:\prueba.txt", OpenMode.Append)
    PrintLine(FF, "texto")
    FileClose(FF)

Dim uni As New UnicodeEncoding
        Dim Contra As Byte() = uni.GetBytes(TextBox1.Text)
        Dim DATOS As New DESCryptoServiceProvider        
Dim encriptador As ICryptoTransform = DATOS.CreateEncryptor(DATOS.Key, DATOS.IV)
        Dim encrmemo As New MemoryStream()
        Dim cryptoStream As New CryptoStream(encrmemo, encriptador, CryptoStreamMode.Write)
        cryptoStream.Write(Contra, 0, Contra.Length)
        cryptoStream.Close()
        Dim StrEncr As Byte() = encrmemo.ToArray()

        'DESENC
        Dim DESencriptador As ICryptoTransform = DATOS.CreateDecryptor(DATOS.Key, DATOS.IV)
        Dim DESencrmemo As New MemoryStream(StrEncr)
        Dim DEScryptoStream As New CryptoStream(DESencrmemo, DESencriptador, CryptoStreamMode.Read)
        Dim message As String
        message = New StreamReader(DEScryptoStream).ReadToEnd()



        MsgBox(message)

Dim message As Byte() = Codificacion.GetBytes(strCadena)

Dim criptoProvider As New TripleDESCryptoServiceProvider

Dim criptoTransform As ICryptoTransform = criptoProvider.CreateEncryptor(criptoProvider.Key, criptoProvider.IV)

Dim memorystream As New MemoryStream

Dim cryptoStream As New CryptoStream(memorystream, criptoTransform, CryptoStreamMode.Write)

cryptoStream.FlushFinalBlock()

Dim cifrado As Byte() = memorystream.ToArray

Dim cadenaEncriptada = Codificacion.GetString(cifrado)

Return cadenaEncriptada