Captcha Generator in Asp.net WebForms

Step1: Open the project in Asp.Net Web Application & named it      “CaptchaGenerator”

Step2: Select “Empty” with “WebForm” keep other options unchecked

Step3: Right Click on “CaptchaGenerator” & select  ‘Add’ to add webforms, name it as “Login.aspx” , “Home.aspx” and “Captchaimage.aspx”

Step4: Add “Images” folder & store refresh.jpg image in it

Step5: Add following code inside <div> in   Login.aspx

<asp:ScriptManager ID="ScriptManager1" runat="server"></asp:ScriptManager>

            <table style="border:3px solid blue;margin-left:auto;margin-right:auto;">

                <caption>Login Form</caption>

                <tr>

<td>User Name :</td>

                    <td>

                        <asp:TextBox ID="txtName" runat="server" Width="150"></asp:TextBox>

                    </td>

                </tr>

                <tr>

                    <td>Password&nbsp;&nbsp; :</td>

                    <td>

                        <asp:TextBox ID="txtPwd" runat="server" TextMode="Password" Width="150"></asp:TextBox>

                    </td>

                </tr>

                <tr>

                    <td>Captcha&nbsp;&nbsp;&nbsp; :</td>

                    <td>

                        <asp:UpdatePanel ID="updatePanel1" runat="server">

                            <ContentTemplate>

                                <asp:Image ID="imgCaptcha" runat="server" BorderStyle="Solid" Width="100" Height="30" />

                        <asp:ImageButton ID="btnRefresh" runat="server" ImageUrl="~/Images/refresh.jpg" Height="30px" Width="30px" OnClick="btnRefresh_Click" />

                            </ContentTemplate>

                        </asp:UpdatePanel>

                    </td>

                </tr>

                <tr>

                    <td>Enter Captcha :</td>

                    <td>

                        <asp:TextBox ID="txtCaptcha" runat="server" Width="150" AutoCompleteType="Disabled"></asp:TextBox>

                    </td>

                </tr>

                <tr>

                    <td colspan="2" style="align-content:center">

                        <asp:Button ID="btnCaptchaLogin" runat="server" Text="Login with Captcha" Width="123px" OnClick="btnCaptchaLogin_Click" />

                    </td>

                </tr>

                <tr>

                    <td colspan="2" style="align-content:center">

                        <asp:Label ID="lblStatus" runat="server" ForeColor="Red" Text="Messages"></asp:Label>

                    </td>

                </tr>

            </table>

Step6: Right click on Login.aspx & goto ViewCode and write following code

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

namespace CaptchaGenrator

{

    public partial class Login : System.Web.UI.Page

    {

        protected void Page_Load(object sender, EventArgs e)

        {

            if (!IsPostBack)

                GenerateCaptcha();

        }

        private void GenerateCaptcha()

        {

            string values = "0123456789abcdefghijklmopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";

            StringBuilder strCaptcha = new StringBuilder();

            Random random = new Random();

            for(int i=0;i<=6;i++)

            {

                int randomValue = random.Next(values.Length);

                strCaptcha.Append(values[randomValue]);

            }

            Session["Captcha"] = strCaptcha.ToString();

            imgCaptcha.ImageUrl = "~/Captchaimage.aspx?" + DateTime.Now.Ticks;

        }

        protected void btnRefresh_Click(object sender, ImageClickEventArgs e)

        {

            GenerateCaptcha();

        }

        protected void btnCaptchaLogin_Click(object sender, EventArgs e)

        {

            if(Session["Captcha"].ToString() != txtCaptcha.Text)

            {

                lblStatus.Text = "Wrong Captcha, Please try again";

                txtCaptcha.Text = "";

                GenerateCaptcha();

            }

            else

            {

                if(txtName.Text == "Pankaj" && txtPwd.Text == "12345")

                {

                    Response.Redirect("Home.aspx");

                }

                else

                    lblStatus.Text = "Invalid Username $ Password,Please try again";

                GenerateCaptcha();

            }

        }

    }

}

Step7: Right click on Captchaimage.aspx & goto ViewCode and write following code

using System;

using System.Collections.Generic;

using System.Drawing;

using System.Drawing.Imaging;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

namespace CaptchaGenrator

{

    public partial class Captchaimage : System.Web.UI.Page

    {

        protected void Page_Load(object sender, EventArgs e)

        {

           

            int Width =100 , Height = 30;

            Bitmap bmp = new Bitmap(Width, Height);

            Graphics g = Graphics.FromImage(bmp);

            g.Clear(Color.White);

            g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;

            g.PixelOffsetMode = System.Drawing.Drawing2D.PixelOffsetMode.HighQuality;

            Rectangle rect = new Rectangle(1, 1, Width - 2, Height - 2);

            g.DrawRectangle(new Pen(Color.Red), rect);

            g.FillRectangle(new SolidBrush(Color.Bisque), rect);

            g.DrawString(Session["Captcha"].ToString(), new Font("ArialBlack",12, FontStyle.Italic), Brushes.Black, 10, 5);

            g.DrawBezier(new Pen(Color.Yellow), new Point(0, 5), new Point(10, 10), new Point(10, 20), new Point(100, 5));

            Response.ContentType = "image/jpeg";

            bmp.Save(Response.OutputStream, ImageFormat.Jpeg);

        }

    }

}

Step8: Goto Home.aspx & write following code in <div>

<h1 style="text-align:center; background-color:burlywood;color:white;border:double">Welcome To Home Page</h1>

Step9: Run Login.aspx enter the proper Username , Password & Captcha

Click on ‘Login With Captcha’ button ,login page will redirect to Home page. 

PostedBy: pankaj_bhakre