Secure XML parsing in C #

Question

I have a C # application that receives an array of bytes from an external service representing a UTF-8 encoded XML message. This XML data contains sensitive data that I would prefer not to store in a string object, since the strings are immutable and I cannot erase the values ​​when I finish with them. I am currently using System.XML.XmlReader to parse values ​​as strings (see code below). How can I do this without my code (or the code that I call) to store sensitive data as a string?

        byte[] messsage = Encoding.UTF8.GetBytes(request);
        // Send message to the server. 
        sslStream.Write(messsage);
        sslStream.Flush();

        // read the response
        byte[] buffer = new byte[2048];
        StringBuilder messageData = new StringBuilder();
        int bytes = -1;
        do
        {
            bytes = sslStream.Read(buffer, 0, buffer.Length);

            // Use Decoder class to convert from bytes to UTF8
            // in case a character spans two buffers.
            Decoder decoder = Encoding.UTF8.GetDecoder();
            char[] chars = new char[decoder.GetCharCount(buffer, 0, bytes)];
            decoder.GetChars(buffer, 0, bytes, chars, 0);
            messageData.Append(chars);
            // Check for ending tag.
            if (messageData.ToString().IndexOf(expectedEndTag) != -1)
            {
                break;
            }
        } while (bytes > 0);

        string response = messageData.ToString();

        using (XmlReader reader = XmlReader.Create(new StringReader(response)))
        {
            reader.ReadToFollowing("Success");
            string successVal = reader.ReadElementContentAsString();
            success = bool.Parse(successVal);
        }

Answer 1

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