Showing posts with label dynamic captch code. Show all posts
Showing posts with label dynamic captch code. Show all posts

Saturday, August 18, 2018

how to create dynamic captch code, any website, any registration form etc Prevent Bot Attacks any website form | Sradha Webcreations

how to create dynamic captch code, any website, any registration form etc  Prevent Bot Attacks  any website form

Default.aspx
<%@ Page Language="C#" AutoEventWireup="true"  CodeFile="Default.aspx.cs" Inherits="_Default" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
         <asp:Label ID="lblmsg" runat="server" Font-Bold="True"
       ForeColor="Red" Text=""></asp:Label>
         <br />
    </div>
    <asp:TextBox ID="txtimgcode" runat="server"></asp:TextBox>
    <br />
    <asp:Image ID="Image1" runat="server" ImageUrl="~/CImage.aspx"/>
    <br />
    <asp:Button ID="Button1" runat="server" onclick="Button1_Click" Text="Button" />
    </form>
</body>
</html>

Default.aspx.cs
using System;
using System.Collections.Generic;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        if (this.txtimgcode.Text == this.Session["CaptchaImageText"].ToString())
        {
            lblmsg.Text = "Excellent.......";
        }
        else
        {
            lblmsg.Text = "image code is not valid.";
        }
        this.txtimgcode.Text = "";
    }
}
CImage.aspx.cs(link page of image)
using System;
using System.Collections.Generic;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Drawing.Imaging;
public partial class CImage : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        // Create a random code and store it in the Session object.
        this.Session["CaptchaImageText"] = GenerateRandomCode();
        // Create a CAPTCHA image using the text stored in the Session object.
        RandomImage ci = new RandomImage(this.Session
            ["CaptchaImageText"].ToString(), 300, 75);
        // Change the response headers to output a JPEG image.
        this.Response.Clear();
        this.Response.ContentType = "image/jpeg";
        // Write the image to the response stream in JPEG format.
        ci.Image.Save(this.Response.OutputStream, ImageFormat.Jpeg);
        // Dispose of the CAPTCHA image object.
        ci.Dispose();
    }

    // Function to generate random string with Random class.
    private string GenerateRandomCode()
    {
        Random r = new Random();
        string s = "";
        for (int j = 0; j < 5;j++)
        {
            int i = r.Next(3);
            int ch;
            switch (i)
            {
                case 1:
                    ch = r.Next(0, 9);
                    s = s + ch.ToString();
                    break;
                case 2:
                    ch = r.Next(65, 90);
                    s = s + Convert.ToChar(ch).ToString();
                    break;
                case 3:
                    ch = r.Next(97, 122);
                    s = s + Convert.ToChar(ch).ToString();
                    break;
                default:
                    ch = r.Next(97, 122);
                    s = s + Convert.ToChar(ch).ToString();
                    break;
            }
            r.NextDouble();
            r.Next(100, 1999);
        }
        return s;
    }}
Add a class file in the website……..
Name the class file as RandomImage.cs…….


RandomImage.cs
//Extra name space
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.Drawing.Text;
using System;
public class RandomImage
{
    //Default Constructor
    public RandomImage() { }
    //property
    public string Text
    {
        get { return this.text; }
    }
    public Bitmap Image
    {
        get { return this.image; }
    }
    public int Width
    {
        get { return this.width; }
    }
    public int Height
    {
        get { return this.height; }
    }
    //Private variable
    private string text;
    private int width;
    private int height;
    private Bitmap image;
    private Random random = new Random();
    //Methods declaration
    public RandomImage(string s, int width, int height)
    {
        this.text = s;
        this.SetDimensions(width, height);
        this.GenerateImage();
    }
    public void Dispose()
    {
        GC.SuppressFinalize(this);
        this.Dispose(true);
    }
    protected virtual void Dispose(bool disposing)
    {
        if (disposing)
            this.image.Dispose();
    }
    private void SetDimensions(int width, int height)
    {
        if (width <= 0)
            throw new ArgumentOutOfRangeException("width", width,
                "Argument out of range, must be greater than zero.");
        if (height <= 0)
            throw new ArgumentOutOfRangeException("height", height,
                "Argument out of range, must be greater than zero.");
        this.width = width;
        this.height = height;
    }
    private void GenerateImage()
    {
        Bitmap bitmap = new Bitmap
          (this.width, this.height, PixelFormat.Format32bppArgb);
        Graphics g = Graphics.FromImage(bitmap);
        g.SmoothingMode = SmoothingMode.AntiAlias;
        Rectangle rect = new Rectangle(0, 0, this.width, this.height);
        HatchBrush hatchBrush = new HatchBrush(HatchStyle.SmallConfetti, Color.LightGray, Color.White);
        g.FillRectangle(hatchBrush, rect);
        SizeF size;
        float fontSize = rect.Height + 1;
        Font font;
        do
        {
            fontSize--;
            font = new Font(FontFamily.GenericSansSerif, fontSize, FontStyle.Bold);
            size = g.MeasureString(this.text, font);
        } while (size.Width > rect.Width);
        StringFormat format = new StringFormat();
        format.Alignment = StringAlignment.Center;
        format.LineAlignment = StringAlignment.Center;
        GraphicsPath path = new GraphicsPath();
        //path.AddString(this.text, font.FontFamily, (int) font.Style,
        //    font.Size, rect, format);
        path.AddString(this.text, font.FontFamily, (int)font.Style, 75, rect, format);
        float v = 4F;
        PointF[] points =
          {
                new PointF(this.random.Next(rect.Width) / v, this.random.Next( rect.Height) / v),
             new PointF(rect.Width - this.random.Next(rect.Width) / v, this.random.Next(rect.Height) / v),
                new PointF(this.random.Next(rect.Width) / v, rect.Height - this.random.Next(rect.Height) / v),
 new PointF(rect.Width - this.random.Next(rect.Width) / v,rect.Height - this.random.Next(rect.Height) / v)
          };
        Matrix matrix = new Matrix();
        matrix.Translate(0F, 0F);
        path.Warp(points, rect, matrix, WarpMode.Perspective, 0F);
        hatchBrush = new HatchBrush(HatchStyle.Percent10, Color.Black, Color.SkyBlue);
        g.FillPath(hatchBrush, path);
        int m = Math.Max(rect.Width, rect.Height);
       for (int i = 0; i < (int)(rect.Width * rect.Height / 30F); i++)
        {
            int x = this.random.Next(rect.Width);
            int y = this.random.Next(rect.Height);
            int w = this.random.Next(m / 50);
            int h = this.random.Next(m / 50);
            g.FillEllipse(hatchBrush, x, y, w, h);
        }
        font.Dispose();
        hatchBrush.Dispose();
        g.Dispose();
        this.image = bitmap;
    }
}