[سؤال] بخصوص تشفير ملف txt - نسخة قابلة للطباعة

كود :
Public Function Encrypt(ByVal text As String, ByVal key As String) As String

        Try

            Dim crp As New TripleDESCryptoServiceProvider

            Dim uEncode As New UnicodeEncoding

            Dim bytPlainText() As Byte = uEncode.GetBytes(text)

            Dim stmCipherText As New MemoryStream

            Dim slt() As Byte = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12}

            Dim pdb As New Rfc2898DeriveBytes(key, slt)

            Dim bytDerivedKey() As Byte = pdb.GetBytes(24)

            crp.Key = bytDerivedKey

            crp.IV = pdb.GetBytes(8)

            Dim csEncrypted As New CryptoStream(stmCipherText, crp.CreateEncryptor(), CryptoStreamMode.Write)

            csEncrypted.Write(bytPlainText, 0, bytPlainText.Length)

            csEncrypted.FlushFinalBlock()

            Return Convert.ToBase64String(stmCipherText.ToArray())

        Catch ex As Exception

            MsgBox(ex.Message, MsgBoxStyle.Critical, "Error")

            Return Nothing

        End Try

    End Function

    Function Decrypt(ByVal text As String, ByVal key As String) As String

        Dim crp As TripleDESCryptoServiceProvider

        Try

            crp = New TripleDESCryptoServiceProvider

            Dim uEncode As New UnicodeEncoding

            Dim bytCipherText() As Byte = Convert.FromBase64String(text)

            Dim stmPlainText As New MemoryStream

            Dim stmCipherText As New MemoryStream(bytCipherText)

            Dim slt() As Byte = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12}

            Dim pdb As New Rfc2898DeriveBytes(key, slt)

            Dim bytDerivedKey() As Byte = pdb.GetBytes(24)

            crp.Key = bytDerivedKey

            crp.IV = pdb.GetBytes(8)



            Dim csDecrypted As New CryptoStream(stmCipherText, crp.CreateDecryptor(), CryptoStreamMode.Read)

            Dim sw As New StreamWriter(stmPlainText)

            Dim sr As New StreamReader(csDecrypted)

            sw.Write(sr.ReadToEnd)

            sw.Flush()

            csDecrypted.Clear()

            crp.Clear()

            Return uEncode.GetString(stmPlainText.ToArray())

        Catch ex As Exception

            MsgBox(ex.Message, MsgBoxStyle.Critical, "Error")

            Return Nothing

        End Try

    End Function