How to Encrypt and decrypt xml files in C#

In this post we are going to encrypt and decrypt xml files using RijndaelManaged class.

this class will be in System.Security.Cryptography namespace.

The System.Security.Cryptography namespace provides cryptographic services, including secure encoding and decoding of data.

Encrypt

    public static void EncryptAndSerialize(Object obj)

    {

        UnicodeEncoding aUE = new UnicodeEncoding();

        byte[] key = aUE.GetBytes("password");

        RijndaelManaged RMCrypto = new RijndaelManaged();

        using (FileStream fs = File.Open(@"D:\Sample.xml", FileMode.Create))

        {

        using (CryptoStream cs = new CryptoStream(fs, RMCrypto.CreateEncryptor(key,   key), CryptoStreamMode.Write))

            {

                XmlSerializer xmlser = new XmlSerializer(obj.GetType());

                xmlser.Serialize(cs, obj);

            }

            fs.Close();

    }

Decrypt

public static DataSet DecryptAndDeserialize(string filename)

    {

        DataSet ds = new DataSet();

        FileStream aFileStream = new FileStream(filename, FileMode.Open);

        StreamReader aStreamReader = new StreamReader(aFileStream);

        UnicodeEncoding aUE = new UnicodeEncoding();

        byte[] key = aUE.GetBytes("password");

        RijndaelManaged RMCrypto = new RijndaelManaged();

        CryptoStream aCryptoStream = new CryptoStream(aFileStream, RMCrypto.CreateDecryptor(key, key),     CryptoStreamMode.Read);

        //Restore the data set to memory.

        ds.ReadXml(aCryptoStream);

        aStreamReader.Close();

        aFileStream.Close();

       return ds;

    }

For more info Refer following links

http://msdn.microsoft.com/en-us/library/system.security.cryptography.aspx

http://msdn.microsoft.com/en-us/library/system.security.cryptography.cryptostream.aspx

Adding and updating column to an Existing XML file in C#

// creating dataset

DataSet ds = new DataSet();

       

// Reading XML file through ReadXml method which reads XML file and converts into Data Tables

ds.ReadXml("XMLFilePath");

// adding Required Column to an existing Table in dataset, here I am assuming my table is in '0' position in Dataset.

 ds.Tables[0].Columns.Add("ColumnName", typeof(string));

 // Here assigning value to Added Column

 for (int i = 0; i < ds.Tables[0].Rows.Count; i++)

  {

   ds.Tables[0].Rows[i]["ColumnName"] = "Test";

  }

// writing dataset to xml file, xml file will be update with new column (Recently Added)

ds.WriteXml("XMLFilePath");

Microsoft Visual C# 2010 Step by Step

Loading relational tables into DataGridView in C#.NET and Winforms

In this post we can see how to show relational tables in the datagridview.

For this sample I have taken Nortwind as my database and I have selected Customers and Orders Tables.

o    Let’s take a new windows application.

o    Add one form to it.

o    Copy and paste the below code in form.cs file

 private DataGridView customerDataGridView = new DataGridView();

 private BindingSource customerBindingSource = new BindingSource();

 private DataGridView ordersDataGridView = new DataGridView();

 private BindingSource ordersBindingSource = new BindingSource();

 public Form1()

   {

 InitializeComponent();

 customerDataGridView.Dock = DockStyle.Fill;

 customerDataGridView.SelectionMode = DataGridViewSelectionMode.FullRowSelect;

 customerDataGridView.AllowUserToAddRows = false;

 customerDataGridView.AllowUserToDeleteRows = false;

 ordersDataGridView.Dock = DockStyle.Fill;

 ordersDataGridView.SelectionMode = DataGridViewSelectionMode.FullRowSelect;

 customerDataGridView.AllowUserToAddRows = false;

 customerDataGridView.AllowUserToDeleteRows = false;

 SplitContainer splitContainer1 = new SplitContainer();

 splitContainer1.Dock = DockStyle.Fill;

 splitContainer1.Orientation = Orientation.Horizontal;

 splitContainer1.Panel1.Controls.Add(customerDataGridView);

 splitContainer1.Panel2.Controls.Add(ordersDataGridView);

 this.Controls.Add(splitContainer1);

 this.Load += new System.EventHandler(Form1_Load);

 this.Text = "Loading relational tables into DataGridView";

   }

 private void Form1_Load(object sender, EventArgs e)

        {

 // Bind the DataGridView controls to the BindingSource

 // components and load the data from the database.

 customerDataGridView.DataSource = customerBindingSource;

 ordersDataGridView.DataSource = ordersBindingSource;

GetData();

 // Resize the master DataGridView columns to fit the newly loaded data.

 customerDataGridView.AutoResizeColumns();

 // Configure the details DataGridView so that its columns automatically

 // adjust their widths when the data changes.

 ordersDataGridView.AutoSizeColumnsMode =

 DataGridViewAutoSizeColumnsMode.AllCells;

        }

private void GetData()

    {

 try

  {

    // Specify a connection string. Replace the given value with a

// valid connection string for a Northwind SQL Server sample

// database accessible to your system.

String connectionString = "Server=localhost; uid=sa;pwd=sa@123;       database=Northwind";

SqlConnection connection = new SqlConnection(connectionString);

// Create a DataSet.

DataSet data = new DataSet();

data.Locale = System.Globalization.CultureInfo.InvariantCulture;

// Add data from the Customers table to the DataSet.

SqlDataAdapter masterDataAdapter = new

SqlDataAdapter("select * from customers", connection);

masterDataAdapter.Fill(data, "Customers");

 // Add data from the Orders table to the DataSet.

 SqlDataAdapter detailsDataAdapter = new

 SqlDataAdapter("select * from Orders", connection);

 detailsDataAdapter.Fill(data, "Orders");

 // Establish a relationship between the two tables.

 DataRelation relation = new DataRelation("CustomersOrders",

 data.Tables["Customers"].Columns["customerID"],

 data.Tables["Orders"].Columns["customerID"]);

 data.Relations.Add(relation);

 // Bind the master data connector to the Customers table.

 customerBindingSource.DataSource = data;

 customerBindingSource.DataMember = "Customers";

  // Bind the details data connector to the master data connector,

  // using the DataRelation name to filter the information in the

  // details table based on the current row in the master table.

  ordersBindingSource.DataSource = customerBindingSource;

  ordersBindingSource.DataMember = "CustomersOrders";

    }

  catch (SqlException ex)

   {

                MessageBox.Show("sql connection has not been established”);

    }

 }

Adding new Record to Existing XML File using C-Sharp

1)     Creating Employee class with four properties EmpId, DeptId, EmpName, Location

2)     Reading an XML file into a DataTable

3)     Adding new record to above created Data table

4)     Creating xml file using Data table

namespace AddnewRecordtoExistinXMlFile

{

    public class Employee

    {

        public int EmpId

        {

            get;

            set;

        }

        public int DeptId

        {

            get;

            set;

        }

        public string  EmpName

        {

            get;

            set;

        }

        public string Location

        {

            get;

            set;

        }

     }

   class Program

    {

                

      // create object for Employee class

        Employee objEmp = new Employee();

        // <summary>

        /// methods for Creating an XML file from DataTable

        /// </summary>

        public void CreateXMlDoc()

        {

           

            DataTable dtEmployee = ReadXML("CreateEmployee.xml");

            // assigning values to Employee Object

            objEmp.EmpId = 2;

            objEmp.DeptId = 1;

            objEmp.EmpName = "XYZ";

            objEmp.Location = "Hyderabad";

         

     // adding Employee Object values to datarow.

            DataRow dr = dtEmployee.NewRow();

            dr["EmpId"] = objEmp.EmpId;

            dr["DeptId"] = objEmp.DeptId;

            dr["EmpName"] = objEmp.EmpName;

            dr["Location"] = objEmp.Location;

            dtEmployee.Rows.Add(dr);

            dtEmployee.WriteXml("CreateEmployee.xml");

         }

        // <summary>

        /// method for reading an XML file into a DataTable

        /// </summary>

        /// <param name="file">name (and path) of the XML file</param>

        /// <returns></returns>

        public DataTable ReadXML(string file)

        {

            //create the DataTable that will hold the data

            DataTable table = new DataTable("Employee");
            //create the table with the appropriate column names

            table.Columns.Add("EmpId", typeof(int));

            table.Columns.Add("DeptId", typeof(int));

            table.Columns.Add("TraderName", typeof(string));

            table.Columns.Add("EmpName", typeof(string));

            try

            {

                //open the file using a Stream

if (File.Exists(file))

{

   using (Stream stream = new FileStream(file, FileMode.Open,

   FileAccess.Read))

   {

   //use ReadXml to read the XML stream

   table.ReadXml(stream);

  //return the results

  }

}

 return table;

}

            catch (Exception ex)

            {

                return table;

            }

        }

        static void Main(string[] args)

        {

            Program p=new Program();

            p.PrepareXMlDoc();

            Console.ReadKey();

        }

    }

}

Note : the above scenario will work if and only if Exiting Xmlfile records and new record have the same structure, otherwise it will override with new record, and the existing records in the Xmlfile will be lost.

Sample Xml file

  <?xml version="1.0" standalone="yes" ?>

<DocumentElement>

<Employee>

  <EmpId>1</ EmpId>

  <DeptId>1</ DeptId>

  <EmpName>John</ EmpName>

  < Location>Hyderabad</ Location>

   </ Employee >

  < Employee >

  < EmpId >2</ EmpId >

  < DeptId >2</ DeptId >

  < EmpName>Harry</EmpName>

  <Location>Bangalore</ Location>

</ Employee >

</DocumentElement>

Online Quiz Application Using XML and C#.

This article describes how to create a web quiz from the information in a Xml File and c#. A quiz is a great way to test your knowledge. An online quiz is a great addition to your web site that could keep your visitors glued for a few more minutes. I developed this application using c# and xml data. I have seen several examples like this but I found all applications are in vb.net. so, I have taken some suggestion from that articles and I developed this application.

Please take one Xml file Named as Quiz.xml.

XML Data

Data for the online quiz is kept in an XML document named quiz.xml A valid XML document consists of a root element called quiz, which has at least one element called mchoice (short for multiple-choice). Each mchoice element has one question child element, and two or more answer child elements. The answer element may have the correct attribute with possible value of either yes or no. In fact, you should supply the correct attribute with a value of yes to one of the answers in the same mchoice, otherwise there will be no correct answer for the question.

<?xml version="1.0" encoding="UTF-8"?>

<quiz xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" >

     <mchoice>

           <question>C# (C-Sharp) was developed by</question>

           <answer>Sun Microsystems</answer>

           <answer correct="yes">Microsoft</answer>

           <answer>Intel</answer>

           <answer>IBM</answer>

     </mchoice>

     <mchoice>

           <question>What is C# (C-Sharp)?</question>

           <answer>An Operating System </answer>

           <answer>An Programming Tool </answer>

           <answer correct="yes">An Programming Language </answer>

           <answer> None of these </answer>

     </mchoice>

     <mchoice>

           <question>C# (C-Sharp) belong to which framework ?</question>

           <answer correct="yes">.NET</answer>

           <answer>Java</answer>

           <answer>It does't belong to any framework</answer>

           <answer>None of these</answer>

     </mchoice>

     <mchoice>

           <question>What is CLR ?</question>

           <answer correct="yes">     Common Language Runtime</answer>

           <answer>Conventional Language Runtime</answer>

           <answer>Clarified Language Runtime</answer>

           <answer>Colloquial Language Runtime</answer>

     </mchoice>

     <mchoice>

           <question>Object Oriented Programming (OOP) is a style of programming in which your code is broken up into units, known as</question>

           <answer>objects</answer>

           <answer correct="yes">objects and classes</answer>

           <answer>classes</answer>

           <answer>objects or classes</answer>

     </mchoice>

     <mchoice>

           <question>There are, however, some advanced features of C++, such as __ that are not supported in .NET, and are therefore, not available in managed code.</question>

           <answer>Runtime classes</answer>

           <answer correct="yes">templates</answer>

           <answer>base classes</answer>

           <answer>multiple-document-interfaces</answer>

     </mchoice>

     <mchoice>

           <question>Using C# you can, for example, write a ___ web page?</question>

           <answer>dynamic</answer>

           <answer correct="yes">static</answer>

           <answer>standard</answer>

           <answer>classical</answer>

     </mchoice>

     <mchoice>

           <question>Using C# you can, for example, write ___ of a distributed application?</question>

           <answer>a core</answer>

           <answer>an array</answer>

           <answer>a structure</answer>

           <answer correct="yes">a component</answer>

     </mchoice>

<mchoice>

            <question>  What actually manages your code ?</question>

            <answer>JIT</answer>

            <answer correct="yes">CTS</answer>

            <answer >CLR</answer>

            <answer>CLS</answer>

      </mchoice>

      <mchoice>

            <question>When the . NET runtime loads and runs code, this is the language that it expects to find the code in.</question>

            <answer>Intermediate Language</answer>

            <answer>Common Type System</answer>

            <answer correct="yes">Just-in-Time Compilation</answer>

            <answer>Globally Unique IDentifiers</answer>

      </mchoice>

      <mchoice>

            <question>  When you compile managed code, the ____ actually emits IL.</question>

            <answer>debugger</answer>

            <answer>collector</answer>

            <answer correct="yes">translator</answer>

            <answer>compiler</answer>

      </mchoice>

      <mchoice>

            <question>  ____ this is a minimum set of standards that guarantees that code can be accessed from any language.</question>

            <answer correct="yes">Common Type System</answer>

            <answer>Common Language Specification</answer>

            <answer >Just-in-Time Compilation</answer>

            <answer>The .NET Runtime</answer>

      </mchoice>

      <mchoice>

            <question>Common Language Specification: This is a minimum set of standards that guarantees that code can be accessed from any</question>

            <answer >compiler</answer>

            <answer>stage</answer>

            <answer correct="yes">application</answer>

            <answer>language</answer>

      </mchoice>

      <mchoice>

            <question>Just-in-Time (JIT) Compilation: This is the term for the process of performing the ___ stage of compilation from IL into native machine code.</question>

            <answer correct="yes">intermediate</answer>

            <answer>beginning</answer>

            <answer >final</answer>

            <answer>whole</answer>

      </mchoice>

      <mchoice>

            <question>The function call generated by a non-OOP compiler causes what is called ___ binding</question>

            <answer>weak</answer>

            <answer correct="yes">strong</answer>

            <answer>early</answer>

            <answer>late</answer>

      </mchoice>

      <mchoice>

            <question>You create a string reference:</question>

            <answer>string {s};</answer>

            <answer>string [s];</answer>

            <answer>string (s);</answer>

            <answer correct="yes">string s;</answer>

      </mchoice>

      <mchoice>

            <question>  When you create a reference, you want to connect it with a new object. You do so, in general, with the</question>

            <answer>single quote</answer>

            <answer>double quote</answer>

            <answer correct="yes">round brackets</answer>

            <answer >new keyword</answer>

      </mchoice>

      <mchoice>

            <question>There are six different places to store data. This is a general-purpose pool of memory (also in the RAM area) where all C# objects live.</question>

            <answer>Registers</answer>

            <answer>The heap</answer>

            <answer >Static storage</answer>

            <answer correct="yes">The stack</answer>

      </mchoice>

</quiz>

The user interface will allow application users to click on the "Start Quiz" button to start the quiz. The quiz will have 20 questions and each question may have more or one answers. The question with single answer should have radio boxes to select an answer and the questions with multiple choices should have check boxes to select the answers.
In the end of the quiz, the results will be displayed to the user by percentage of correct answers and total questions. For example, if a user answers 16 questions correctly, he should see his result as 80%.

Then take one aspx page named as Default.aspx:
Write the following code in aspx page.

<html xmlns="http://www.w3.org/1999/xhtml">

<head runat="server">

    <title>Online Quiz</title>

<style>

body {

  font-size: 11px;

  font-family: verdana;

  color:#000000;

  background-color:#EEE;

}

.tableborder

{

     border: 1px dotted #99CC33;

}

.whitetable

{

     color: #000000;

     background-color: #ffffff;

     font-size: 11px;

     padding: 6px;

     font-family: Verdana;

}

.whitetable td

{

     font-size: 11px;

     font-family: Verdana;

}

tr.heading

{

    padding: 6px 0px 0px 6px;

     background: #EBF3FB;

     border: 1px solid #ACE;

}

 .button

 {

       font-family: Verdana;

       font-size: 11px;

       font-weight: normal;

       list-style-type: none;

       border: 1px solid #cccccc;

       background-color: #F0F0EB;

       color: #000;

       height: 24px;

       cursor :pointer ;

       background-image: url(background.jpg);

}

</style>

</head>

<body>

<span id="QuizScreen" runat="server">

<form id="Form1" runat="server">

  <table  bgcolor="#ffffff" border="0" cellpadding="3" cellspacing="0" class="tableborder" align="center" width="80%">

                    <tr>

                        <td align="left" colspan="2"  bgcolor="#95c03f">

                            <strong><span>C# Quiz</span></strong></td>

                    </tr>

                    <tr>

                        <td align="left" colspan="2" style="border: 1px solid #ACE;">

                     <asp:label id="lblQuestion" runat="server" Font-Bold="True" ForeColor="SteelBlue" /></td>

                    </tr>

            <tr>

                <td align="left" colspan="2" style="border-right: #ace 1px solid; border-top: #ace 1px solid; border-left: #ace 1px solid; border-bottom: #ace 1px solid">

      <asp:radiobuttonlist

          id="rblAnswer"

            RepeatDirection="vertical"

            TextAlign="right"

            RepeatLayout="table"

            runat="server" />

       <asp:requiredfieldvalidator ID="Requiredfieldvalidator1"

            ControlToValidate="rblAnswer"

            ErrorMessage="Please pick an answer!"

            runat="server" /></td>

            </tr>

            <tr>

                <td align="left" colspan="2" style="border-right: #ace 1px solid; border-top: #ace 1px solid; border-left: #ace 1px solid; border-bottom: #ace 1px solid">

      <asp:button id="btnSubmit"  CssClass="button" text="  Next  " onClick="btnSubmit_Click" runat="server" /></td>

            </tr>

            <tr>

                <td align="left" colspan="1" >

                    Total

                    <asp:label id="lblTotalQuestion" runat="server" />&nbsp; Questions</td>

                <td align="right" >

                    Time Spent

                    <asp:label id="lblTimeSpent" runat="server" /></td>

            </tr>

      <tr>

          <td align="left" colspan="1">

          </td>

          <td align="right">

    <asp:TextBox ID="txtCorrectAnswer" runat="server" Visible="False"></asp:TextBox></td>

      </tr>

             

                </table>

</form>

</span>

<span id="ResultScreen" runat="server">

<asp:label id="lblResult" runat="server" /> 

</span>

</body>

</html>

In code behind Default.aspx.cs:
This is coding part. Here I used  view state for maintaining  the state of all correct answers of questions and total answers selected by users etc...,please add System.Xml name space to your code behind  page.

XmlDocument xDoc = new XmlDocument();

    int intTotalQuestion;

    int intQuestionNo = 1;

    int intScore;

    DateTime startTime=DateTime.Now;

    ArrayList arrAnswerHistory = new ArrayList();

    ArrayList arrCorrectAnswers = new ArrayList();

    protected void Page_Load(object sender, EventArgs e)

    {

        //Load xml data

        xDoc.Load("E:/Projects/Csharpxmlquiz/Quiz.xml");

        //Start a new quiz?

        if (!Page.IsPostBack)

        {

            //Yes! Count total question

            intTotalQuestion = xDoc.SelectNodes("/quiz/mchoice").Count;

            //Record start time

            ViewState["StartTime"] = DateTime.Now;

            ShowQuestion(intQuestionNo);

        }

    }

    public void ShowQuestion(int intQuestionNo)

    {

        XmlNodeList xNodeList =default(XmlNodeList);

        XmlNode node;

        string strXPath = null;

        int i = 0;

        TimeSpan tsTimeSpent = default(TimeSpan);

        strXPath = "/quiz/mchoice[" + intQuestionNo.ToString() + "]";

        //Extract question

        lblQuestion.Text = intQuestionNo.ToString() + ". " + xDoc.SelectSingleNode(strXPath + "/question").InnerXml;

        //Extract answers

        xNodeList = xDoc.SelectNodes(strXPath + "/answer");

        //Clear previous listitems

        rblAnswer.Items.Clear();

        for (i = 0; i <= xNodeList.Count - 1; i++)

        {

            //Add item to radiobuttonlist

            rblAnswer.Items.Add(new ListItem(xNodeList.Item(i).InnerText));

            //Extract correct answer

           node = xNodeList.Item(i).Attributes.GetNamedItem("correct");

            if ((node != null))

            {

                if (node.Value == "yes")

                {

                    txtCorrectAnswer.Text = xNodeList.Item(i).InnerText;

                    arrCorrectAnswers.Add(xNodeList.Item(i).InnerText);

                }

            }

        }

        //Output Total Question

        lblTotalQuestion.Text = intTotalQuestion.ToString();

        //Output Time Spent

        tsTimeSpent = DateTime.Now.Subtract((DateTime)ViewState["StartTime"]);

        lblTimeSpent.Text = tsTimeSpent.Minutes.ToString() + ":" + tsTimeSpent.Seconds.ToString();

        //Store essential data to viewstate

        ViewState["TotalQuestion"] = intTotalQuestion;

        ViewState["Score"] = intScore;

        ViewState["QuestionNo"] = intQuestionNo;

        ViewState["AnswerHistory"] = arrAnswerHistory;

        ViewState["CorrectAnswers"] = arrCorrectAnswers;

    }

    protected void btnSubmit_Click(object sender, EventArgs e)

    {

        //Retrieve essential variables from state bag

        intTotalQuestion =Convert.ToInt32( ViewState["TotalQuestion"]);

        intQuestionNo = Convert.ToInt32(ViewState["QuestionNo"]);

        intScore =Convert.ToInt32( ViewState["Score"]);

        arrAnswerHistory = (ArrayList)ViewState["AnswerHistory"];

        arrCorrectAnswers = (ArrayList)ViewState["CorrectAnswers"];

        //Correct answer?

        if (rblAnswer.SelectedItem.Text == txtCorrectAnswer.Text)

        {

            intScore += 1;

            arrAnswerHistory.Add(null);

        }

        else

        {

            arrAnswerHistory.Add(rblAnswer.SelectedItem.Text);

        }

        //End of quiz?

        if (intQuestionNo == intTotalQuestion)

        {

            //Yes! Show the result...

            QuizScreen.Visible = false;

            ResultScreen.Visible = true;

            //Render result screen

            ShowResult();

        }

        else

        {

            //Not yet! Show another question...

            QuizScreen.Visible = true;

            ResultScreen.Visible = false;

            intQuestionNo += 1;

            //Render next question

            ShowQuestion(intQuestionNo);

        }

    }

    public void ShowResult()

    {

        string strResult = null;

        int i ;

        string strXPath = null;

        TimeSpan tsTimeSpent = default(TimeSpan);

        tsTimeSpent = DateTime.Now.Subtract((DateTime)ViewState["StartTime"]);

        strResult = "<center>";

        strResult += "<h3>Quiz Result</h3>";

        strResult += "<p>Points: " + intScore.ToString() + " of " + intTotalQuestion.ToString();

        strResult += "<p>Your Competency: " + (intScore * 100 / intTotalQuestion).ToString() + "%";

        strResult += "<p>Time Spent: " + tsTimeSpent.Minutes.ToString() + ":" + tsTimeSpent.Seconds.ToString();

        strResult += "</center>";

        strResult += "<h3>Scrolldown to review your answers:</h3>";

        for (i = 1; i <= intTotalQuestion; i++)

        {

            strXPath = "/quiz/mchoice[" + i + "]";

            strResult += "<b>" + i.ToString() + ". " + xDoc.SelectNodes(strXPath + "/question").Item(0).InnerXml + "</b><br>";

            if (arrAnswerHistory[i-1] == null)

            {

                strResult += "<b>You answered: </b> " + arrCorrectAnswers[i - 1] + "<font color=\"green\"><b> (Correct)</b></font><br>"+"<br>";

            }

            else

            {

                strResult += "<b>You answered: </b> " + arrAnswerHistory[i - 1] + "<font color=\"red\"><b>(Wrong)</b></font><br>";

                strResult += "<font color=\"green\"><b>CorrectAnswer: </b></font>" + arrCorrectAnswers[i - 1] + "<br><br>";

            }

        }

        lblResult.Text = strResult;

    }

Conclusion:
I hope this application is very useful .