Steganography 13 - Hiding Binary Data in HTML Documents

#region Using directives

using System;
using System.Collections;
using System.Collections.Specialized;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.IO;

#endregion

namespace SteganoHtml {



    partial class MainForm : Form {

        DataSet keySet = new DataSet();
        DataTable keyTable;

        public MainForm() {
            InitializeComponent();
        }

        private void Form2_Load(object sender, EventArgs e) {
            keyTable = keySet.Tables.Add("keyCombinations");
            dgvKey.DataSource = keyTable;

            keyTable.Columns.Add("firstAttribute", typeof(String));
            keyTable.Columns.Add("secondAttribute", typeof(String));

            keyTable.Columns["firstAttribute"].Caption = "First Attribute";
            keyTable.Columns["secondAttribute"].Caption = "Second Attribute";

            keyTable.Columns["firstAttribute"].Unique = true;
            keyTable.Columns["secondAttribute"].Unique = true;

            keyTable.Columns["firstAttribute"].AllowDBNull = false;
            keyTable.Columns["secondAttribute"].AllowDBNull = false;

            keyTable.Rows.Add("width", "height");
            keyTable.Rows.Add("src", "alt");
            keyTable.Rows.Add("style", "class");
            keyTable.Rows.Add("cellspacing", "cellpadding");
        }

        private void IsKeyValid() {
            foreach (DataRow row in keyTable.Rows) {
                if (row[0].ToString().Length == 0) {
                    row[0] = DBNull.Value;
                }
                if (row[1].ToString().Length == 0) {
                    row[1] = DBNull.Value;
                }
            }
        }

        private void btnHide_Click(object sender, EventArgs e)
        {
            HtmlUtility utility = new HtmlUtility();

            int capacity = utility.GetCapacity(txtSrcFileName.Text, keyTable);
            int requiredCapacity = (txtMessageHide.Text.Length + 1) * 8;
            if (requiredCapacity > capacity) {

                String warning = "The document contains not enough attributes.";
                warning += "\r\nCapacity: " + capacity.ToString();
                warning += "\r\nRequired: " + requiredCapacity.ToString();
                MessageBox.Show(warning);

            } else {

                MemoryStream message = new MemoryStream();
                BinaryWriter binaryWriter = new BinaryWriter(message);
                binaryWriter.Write((byte)txtMessageHide.Text.Length);
                binaryWriter.Write( Encoding.Default.GetBytes(txtMessageHide.Text.ToCharArray()) );
                
                this.Cursor = Cursors.WaitCursor;
                utility.Hide(txtSrcFileName.Text, txtDstFileName.Text, message, keyTable);
                this.Cursor = Cursors.Default;

                binaryWriter.Close();

                MessageBox.Show("Finished");
            }
        }

        private void btnExtract_Click(object sender, EventArgs e)
        {
            HtmlUtility utility = new HtmlUtility();
            MemoryStream message = new MemoryStream();

            this.Cursor = Cursors.WaitCursor;
            utility.Extract(txtSrcFileName.Text, message, keyTable);
            this.Cursor = Cursors.Default;

            message.Position = 0;
            StreamReader reader = new StreamReader(message, Encoding.Default);
            String messageText = reader.ReadToEnd();
            txtMessageExtract.Text = messageText;

            reader.Close();
        }

        private String GetSourceFileName(String filter) {
            OpenFileDialog dlg = new OpenFileDialog();
            dlg.Filter = filter;
            if (dlg.ShowDialog(this) == DialogResult.OK) {
                return dlg.FileName;
            } else {
                return null;
            }
        }

        private String GetDestinationFileName(String filter) {
            SaveFileDialog dlg = new SaveFileDialog();
            dlg.Filter = filter;
            if (dlg.ShowDialog(this) == DialogResult.OK) {
                return dlg.FileName;
            } else {
                return null;
            }
        }

        private void btnSrcFileName_Click(object sender, EventArgs e)
        {
            String fileName = GetSourceFileName("HTML Documents (*.html, *.html)|*.html;*.htm");
            if (fileName != null) {
                txtSrcFileName.Text = fileName;
            }
        }

        private void btnDstFileName_Click(object sender, EventArgs e) {
            String fileName = GetDestinationFileName("HTML Documents (*.html, *.html)|*.html;*.htm");
            if (fileName != null) {
                txtDstFileName.Text = fileName;
            }
        }

        private void btnLoadKey_Click(object sender, EventArgs e) {
            String fileName = GetSourceFileName("XML Key Files (*.xml)|*.xml");
            if (fileName != null) {
                keyTable.Clear();
                keyTable.ReadXml(fileName);
            }
        }

        private void btnSaveKey_Click(object sender, EventArgs e) {
            String fileName = GetDestinationFileName("XML Key Files (*.xml)|*.xml");
            if (fileName != null) {
                keyTable.WriteXml(fileName);
            }
        }

        private void dgvKey_Leave(object sender, EventArgs e)
        {
            IsKeyValid();
        }

        private void btnAnalyse_Click(object sender, EventArgs e)
        {
            HtmlUtility utility = new HtmlUtility();
            //free bits = overall bits - 16 bits for message length
            int countBits = utility.GetCapacity(txtSrcFileName.Text, keyTable) - 8;
            if (countBits < 8) {
                MessageBox.Show(
                    "The file cannot hide any data. Add more attribute pairs to your key to raise the capacity."
                    );
            } else {
                int countChars = (int)Math.Floor(((double)countBits) / 8);
                MessageBox.Show(
                    String.Format("The file can hide {0} bits ({1} characters). Add more attribute pairs to your key to raise the capacity.", countBits, countChars)
                    );
            }
        }

        private void txtMessageHide_TextChanged(object sender, EventArgs e)
        {
            lblCountCharacters.Text = txtMessageHide.Text.Length.ToString();
        }

    }
}