How To ADD Simple PHP Captcha

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Telling people and computers automatically is the complete form of CAPTCHA. CAPTCHA is a software to protect the website from intrusion and to determine whether or not it is human. To protect your contact form, comment form and all other forms from spam, you need to add CAPTCHA.

To order to implement the CAPTCHA features on your page, there are many third party solutions. One of CAPTCHA's best-known third party solutions is reCAPTCHA from Google and we launched Google reCAPTCHA earlier with PHP tutorial. However, a simple captcha of PHP is required many times. This tutorial allows you to use PHP on your website to implement CAPTCHA function.

We have created a PHP class CodexWorldCaptcha to give you a highly personalized PHP captcha option. You can easily add captcha to the form by using CodexWorldCaptcha.

CodexWorldCaptcha.php

The core CodexWorldCaptcha class includes 2 creCaptcha() and hexToRgb() functions. The creCaptcha() function is used for HexToRgb() ,so only the creCaptcha() function needs to be called.

<?php


/** 

 *

 * Author: CodexWorld  

 * Author URI: http://www.codexworld.com  

 * Author Email: [email protected]

 * Class Name: CodexWorldCaptcha 

 * Description: CodexWorldCaptcha is a free PHP Captcha script used for generating captcha image.  

 *

 **/

class CodexWorldCaptcha

{

    //Configuration Options

    var $word = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';

    var $length = 5;

    var $img_width = 160;

    var $img_height = 50;

    var $font_path = '';

    var $font_size = 25;

    var $expiration = 7200;

    var $bg_color = '#ffffff';

    var $border_color = '#996666';

    var $text_color = '#cc9999';

    var $grid_color = '#ffb6b6';

    var $shadow_color = '#fff0f0';

    

    public function __construct($config = array()){

        ob_start();

        session_start();

        if (count($config) > 0){

            foreach ($config as $key => $val){

                if (isset($this->$key)){

                    $method = 'set_'.$key;

                    if (method_exists($this, $method)){

                        $this->$method($val);

                    }else{

                        $this->$key = $val;

                    }

                }

            }

        }

        

        if ( ! extension_loaded('gd')){

            return FALSE;

        }

    }

    

    public function createCaptcha(){

        $str = '';

        for ($i = 0; $i < $this->length; $i++){

            $str .= substr($this->word, mt_rand(0, strlen($this->word) -1), 1);

        }

        $word = $str;


        /* Determine angle and position */

        $length = strlen($word);

        $angle  = ($length >= 6) ? rand(-($length-6), ($length-6)) : 0;

        $x_axis = rand(6, (360/$length)-16);

        $y_axis = ($angle >= 0 ) ? rand($this->img_height, $this->img_width) : rand(6, $this->img_height);


        /* Create image */

        if (function_exists('imagecreatetruecolor')){

            $im = imagecreatetruecolor($this->img_width, $this->img_height);

        }else{

            $im = imagecreate($this->img_width, $this->img_height);

        }


        /* Assign colors */

        $bgColorRgb     = $this->hexToRgb($this->bg_color);

        $borderColorRgb = $this->hexToRgb($this->border_color);

        $textColorRgb   = $this->hexToRgb($this->text_color);

        $gridColorRgb   = $this->hexToRgb($this->grid_color);

        $shadowColorRgb = $this->hexToRgb($this->shadow_color);

        $bg_color       = imagecolorallocate ($im, $bgColorRgb[0], $bgColorRgb[1], $bgColorRgb[2]);

        $border_color   = imagecolorallocate ($im, $borderColorRgb[0], $borderColorRgb[1], $borderColorRgb[2]);

        $text_color     = imagecolorallocate ($im, $textColorRgb[0], $textColorRgb[1], $textColorRgb[2]);

        $grid_color     = imagecolorallocate($im, $gridColorRgb[0], $gridColorRgb[1], $gridColorRgb[2]);

        $shadow_color   = imagecolorallocate($im, $shadowColorRgb[0], $shadowColorRgb[1], $shadowColorRgb[2]);


        /* Create the rectangle */

        ImageFilledRectangle($im, 0, 0, $this->img_width, $this->img_height, $bg_color);


        /* Create the spiral pattern */

        $theta   = 1;

        $thetac  = 7;

        $radius  = 16;

        $circles = 20;

        $points  = 32;


        for ($i = 0; $i < ($circles * $points) - 1; $i++){

            $theta = $theta + $thetac;

            $rad   = $radius * ($i / $points );

            $x     = ($rad * cos($theta)) + $x_axis;

            $y     = ($rad * sin($theta)) + $y_axis;

            $theta = $theta + $thetac;

            $rad1  = $radius * (($i + 1) / $points);

            $x1    = ($rad1 * cos($theta)) + $x_axis;

            $y1    = ($rad1 * sin($theta )) + $y_axis;

            imageline($im, $x, $y, $x1, $y1, $grid_color);

            $theta = $theta - $thetac;

        }


        /* Write the text in image */

        $use_font = ($this->font_path != '' AND file_exists($this->font_path) AND function_exists('imagettftext')) ? TRUE : FALSE;


        $x = rand(0, $this->img_width/($length/1.5));

        $y = $this->font_size+2;


        for ($i = 0; $i < strlen($word); $i++)

        {

            if ($use_font == FALSE){

                $y = rand(0 , $this->img_height/2);

                imagestring($im, $this->font_size, $x, $y, substr($word, $i, 1), $text_color);

                $x += ($this->font_size);

            }else{

                $y = rand($this->img_height/2, $this->img_height-3);

                imagettftext($im, $this->font_size, $angle, $x, $y, $text_color, $this->font_path, substr($word, $i, 1));

                $x += $this->font_size;

            }

        }


        /* Create the image border */

        imagerectangle($im, 0, 0, $this->img_width-1, $this->img_height-1, $border_color);


        /* Showing the image */

        imagejpeg($im,NULL,90);

        header('Content-Type: image/jpeg');//image type header

        imagedestroy($im);//destroying image

        

        /* Store captcha code into session */

        if(empty(session_id()))

        unset($_SESSION['captchaCode']);

        $_SESSION['captchaCode'] = $word;

    }

    

    public function hexToRgb($hex){

        $hex = str_replace("#", "", $hex);

        if(strlen($hex) == 3) {

           $r = hexdec(substr($hex,0,1).substr($hex,0,1));

           $g = hexdec(substr($hex,1,1).substr($hex,1,1));

           $b = hexdec(substr($hex,2,1).substr($hex,2,1));

        } else {

           $r = hexdec(substr($hex,0,2));

           $g = hexdec(substr($hex,2,2));

           $b = hexdec(substr($hex,4,2));

        }

        $rgb = array($r, $g, $b);

        return $rgb;

    }

}


?>

index.php

The PHP CAPTCHA form is displayed in this file and the captcha is validated.

<?php

session_start();

if(isset($_POST['submit']) && !empty($_POST['submit'])){

    if(!empty($_POST['captcha_code'])){

        

        //get captcha code from session

        $captchaCode = $_SESSION['captchaCode'];

        

        //get captcha code from input field

        $enteredcaptchaCode = $_POST['captcha_code'];

        

        //verify the captcha code

        if($enteredcaptchaCode === $captchaCode){

            $succMsg = 'Entered captcha code has matched.';

        }else{

            $errMsg = 'Captcha code not matched, please try again.';

        }

        

    }else{

        $errMsg = 'Please enter the captcha code.';

    }

}

?>


<?php if(!empty($errMsg)) echo '<p style="color:#EA4335;">'.$errMsg.'</p>';?>

<?php if(!empty($succMsg)) echo '<p style="color:#34A853;">'.$succMsg.'</p>';?>


<img src="captcha.php" id="capImage"/>

<br/>Can't read the image? click here to  <a href="javascript:void(0);" onclick="javascript:$('#capImage').attr('src','captcha.php');">refresh</a>.

<form method="post">

    Enter the code: <input name="captcha_code" type="text" value="">

    <input type="submit" name="submit" value="SUBMIT">

</form>

The jQuery library should be included to refresh the captcha image.

<script src="//ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>

captcha.php

This file is used by the CodexWorldCaptcha class to generate the captcha image.

<?php

include 'CodexWorldCaptcha.php';

$captchaConfig = array(

     'img_width' => '200',

     'img_height' => '50',

     'font_size' => '30',

     'font_path' => 'fonts/monofont.ttf',

 );

$captcha = new CodexWorldCaptcha($captchaConfig);

$captcha->createCaptcha();

?>