Captcha like google

Create Page Turing.aspx

using System;

using System.Data;

using System.Configuration;

using System.Collections;

using System.Web;

using System.Web.Security;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Web.UI.WebControls.WebParts;

using System.Web.UI.HtmlControls;

using System.Drawing.Text;

using System.Drawing;

using System.Drawing.Drawing2D;

using System.Drawing.Imaging;

using System.Security.Cryptography;

using System.Text;

namespace sunilcaptcha

{

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

{

private static byte[] randb = new byte[4];

private static RNGCryptoServiceProvider rand = new RNGCryptoServiceProvider();

private FontFamily[] fonts = {

new FontFamily("Times New Roman"),

new FontFamily("Georgia"),

new FontFamily("Arial"),

new FontFamily("Comic Sans MS")

};

protected void Page_Load(object sender, EventArgs e)

{

int width = 200;

int hieght = 80;

Random random = new Random();

int ImageNum = RandomNumber(0, 8); // (1-max number of background images)

// Load image

//  Bitmap bitMapImage = new System.Drawing.Bitmap(filename);

Bitmap bitMapImage = new Bitmap(width, hieght, PixelFormat.Format32bppArgb);

Graphics g = Graphics.FromImage(bitMapImage);

Color bc = Color.White;

// Get random string from RandomString(int sizeOfString) method

string textToWrite = RandomString(8);

Rectangle rect = new Rectangle(0, 0, width, hieght);

g.SmoothingMode = SmoothingMode.AntiAlias;

using (SolidBrush b = new SolidBrush(bc))

{

g.FillRectangle(b, rect);

}

// Set up the text font.

int emSize = (int)(width * 5 / textToWrite.Length);

FontFamily family = fonts[Next(fonts.Length - 1)];

Font font = new Font(family, emSize);

// Adjust the font size until the text fits within the image.

SizeF measured = new SizeF(0, 0);

SizeF workingSize = new SizeF(width, hieght);

while (emSize > 2 &&

(measured = g.MeasureString(textToWrite, font)).Width > workingSize.Width ||

measured.Height > workingSize.Height)

{

font.Dispose();

font = new Font(family, emSize -= 2);

}

// Set up the text format.

StringFormat format = new StringFormat();

format.Alignment = StringAlignment.Center;

format.LineAlignment = StringAlignment.Center;

// Create a path using the text and warp it randomly.

GraphicsPath path = new GraphicsPath();

path.AddString(textToWrite, font.FontFamily, (int)font.Style, font.Size, rect, format);

// Set font color to a color that is visible within background color

int bcR = Convert.ToInt32(bc.R);

// This prevents font color from being near the bg color

int red = Next(255), green = Next(255), blue = Next(255);

while (red >= bcR && red - 20 <= bcR ||

red < bcR && red + 20 >= bcR)

{

red = Next(0, 255);

}

//red=26 green=237, blue=

SolidBrush sBrush = new SolidBrush(Color.FromArgb(0, 201, 87));

g.FillPath(sBrush, path);

// Iterate over every pixel

double distort = Next(5, 15) * (Next(10) == 1 ? 1 : -1);

// Copy the image so that we're always using the original for source color

using (Bitmap copy = (Bitmap)bitMapImage.Clone())

{

for (int y = 0; y < hieght; y++)

{

for (int x = 0; x < width; x++)

{

// Adds a simple wave

int newX = (int)(x + (distort * Math.Sin(Math.PI * y / 84.0)));

int newY = (int)(y + (distort * Math.Cos(Math.PI * x / 44.0)));

if (newX < 0 || newX >= width) newX = 0;

if (newY < 0 || newY >= hieght) newY = 0;

bitMapImage.SetPixel(x, y, copy.GetPixel(newX, newY));

}

}

}

Session["randomStr"] = textToWrite.ToLower(); //Encoding.UTF8.GetString(md5.ComputeHash(pass));

System.IO.MemoryStream mstr = new System.IO.MemoryStream();

// Save the image

bitMapImage.Save(mstr, ImageFormat.Jpeg);

// Set the content type

Response.ContentType = "image/png";

// Write image

Response.BinaryWrite((byte[])(mstr).ToArray());

//Clean

font.Dispose();

sBrush.Dispose();

g.Dispose();

bitMapImage.Dispose();

}

public string GetRandomPasswordUsingGUID(int length)

{

// Get the GUID

string guidResult = System.Guid.NewGuid().ToString();

// Remove the hyphens

guidResult = guidResult.Replace("-", string.Empty);

// Return the first length bytes

return guidResult.Substring(0, length);

}

private int RandomNumber(int min, int max)

{

Random random = new Random();

return random.Next(min, max);

}

private string RandomString(int size)

{

string s = "";

char[] chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789".ToCharArray();

int index;

int lenght = Next(8, 8);

for (int i = 0; i < lenght; i++)

{

index = Next(chars.Length - 1);

s += chars[index].ToString();

}

return s;

}

public  int Next()

{

rand.GetBytes(randb);

int value = BitConverter.ToInt32(randb, 0);

if (value < 0) value = -value;

return value;

}

///

/// Generates a random non-negative number less than or equal to max.

///

/// The maximum possible value.

public  int Next(int max)

{

rand.GetBytes(randb);

int value = BitConverter.ToInt32(randb, 0);

value = value % (max + 1); // % calculates remainder

if (value < 0) value = -value;

return value;

}

///

/// Generates a random non-negative number bigger than or equal to min and less than or

///  equal to max.

///

/// The minimum possible value.

/// The maximum possible value.

public  int Next(int min, int max)

{

int value = Next(max - min) + min;

return value;

}

}

}

after the add captcha register.aspx page

<%@ Page Language="C#" AutoEventWireup="true" Codebehind="register.aspx.cs" EnableEventValidation="false"

Inherits="register" %>

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>

<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />

<title>captchatitle>

<script language="Javascript" type="text/javascript">

function refreshSecuritylogin()

{

var randomnumber=Math.floor(Math.random()*1001);

document.images["refreshImg2"].src = "Turing.aspx" + '?rand=' + randomnumber; ;

}

script>

head>

<body >

<form id="form1" runat="server" method="post">

<table width="1000" border="0" align="center" cellpadding="0" cellspacing="0">

<tr>

<td align="left" valign="middle">

<table style="width: 100%">

<tr>

<td width="33%" align="left" height="40" valign="middle" id="Code">

Security Codetd>

<td width="67%" align="left" valign="middle">

<asp:TextBox CssClass="text_field" ID="txtSecurityCode" runat="server" TabIndex="13"

AutoCompleteType="None" MaxLength="8" Style="width: 160px; height: 25px;">asp:TextBox>

<asp:LinkButton ID="lnkRefreshCode" runat="server" OnClick="lnkRefreshCode_Click"

TabIndex="40">

<asp:Label ID="lblRefreshCode" runat="server" Text="Refresh Code" Visible="false" />

asp:LinkButton>

<asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" ControlToValidate="txtSecurityCode"

ErrorMessage="Enter Security Code" ValidationGroup="SignUPpop" Display="none">*asp:RequiredFieldValidator>

td>

tr>

<tr>

<td align="left" valign="top">

td>

<td align="left" valign="top">

<img src="Turing.aspx" class="text_field" alt="refreshImg" name="refreshImg"

id="refreshImg"  height="50px"  width="160px"/>

<br />

<a href="#" onclick="return refreshSecurity();" tabindex="14">Refresh Codea>

td>

tr>

table>                                                td>

<td height="40" align="left" valign="middle">

<asp:ImageButton ID="imgbtnsubmit" runat="server" ValidationGroup="RegisterSignUP"

TabIndex="15" ImageUrl="images/register_2.png" Width="62" Height="28" border="0"

OnClick="imgbtnsubmit_Click" OnClientClick="return ShowModalDialog()" />

<asp:ImageButton ID="ImageButton1" runat="server" Width="49" Height="28" ImageUrl="images/reset.png"

alt="send" border="0" OnClick="ImageButton1_Click" />

td>

tr>

<tr>

<td align="left" valign="middle">

td>

<td align="left" valign="middle">

td>

tr>

table>

div>

div>

td>

tr>

<tr>

<td align="left" valign="top">

td>

tr>

table>

td>

tr>

table>

form>

body>

html>

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