FilteredStream Class

public class FilteredStream : Stream, 
	ICancellableStream

                    public static void Base64EncodeFile (string inputFileName, string outputFileName)
{
    using (var input = File.OpenRead (inputFileName)) {
        using (var output = File.Create (outputFileName)) {
            // A FilteredStream passes all data that is written to (or read from) it through
            // each of its filters, in the order that the filters were added.
            using (var filtered = new FilteredStream (output)) {
                filtered.Add (EncoderFilter.Create (ContentEncoding.Base64));

                input.CopyTo (filtered);

                // Flush the filtered stream so that the encoder writes out any remaining
                // buffered data to the output stream.
                filtered.Flush ();
            }
        }
    }
}
                  

                    public static void DecodeFile (string inputFileName, string outputFileName, string contentTransferEncoding)
{
    using (var input = File.OpenRead (inputFileName)) {
        // Filters can also be used when reading from a FilteredStream. Here, the source stream
        // is the encoded input and reading from the filtered stream yields the decoded content.
        using (var filtered = new FilteredStream (input)) {
            // Create a decoder for the encoding by name, such as "base64" or "quoted-printable".
            filtered.Add (DecoderFilter.Create (contentTransferEncoding));

            using (var output = File.Create (outputFileName))
                filtered.CopyTo (output);
        }
    }
}