1 Security Image Menggunakan PHP

Security image adalah bentuk perlindungan terhadap suatu form dari serangan SPAM. Sebagai contoh, anda mengisi formulir pendaftaran untuk mendapatkan account tertentu dan contoh lainnya adalah pengisian kotak komentar di halaman tertentu yang menggunakan security image.

Screenshot:


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Cara kerjanya:
- Formulir akan menampilkan security code yang di generate oleh script PHP, apabila page tersebut di refresh maka security code akan  di generate lagi sehingga berubah codenya hal ini sangat berguna sekali untuk menangkal serangan spam.
- Setelah di submit, script php akan memvalidasi data anda dan mencocok kan security code yang telah anda masukkan apabila security code tidak sama, maka proses akan di batalkan apabila security code sama, maka proses akan dilanjutkan.

Berikut file-file yang akan digunakan:
- index.html
- action.php
- captcha.php
- DoradoHeadline.ttf

File index.html

<form action="action.php" method="post">
Pesan: 

<textarea cols="50" name="message" rows="10"></textarea>



<img src="captcha.php">

Security Code: <input id="security_code" name="security_code" type="text">

<input name="submit" value="Submit" type="submit"> 
</form>


File action.php

<?php   
session_start(); 
if( isset($_POST['submit'])) { 
   if(($_SESSION['security_code'] == $_POST['security_code']) &&  
(!empty($_SESSION['security_code'])) ) { 
      // masukkan script anda jika validasi benar 
      echo 'Terimakasih Pesan anda sudah muncul
"'.$_POST['message'].'"'; 
   echo "
<a href='index.html'>kembali</a>";
   } else { 
      // masukkan script anda jika validasi salah 
      echo 'Sorry, anda memasukkan security code yang salah
'; 
      include "index.html"; 
   } 
} else { 
      include "index.html"; 
    } 
?>


File captcha.php

<?php 
session_start();

class CaptchaSecurityImages {

   var $font = './DoradoHeadline.ttf';
   
   function generateCode($characters) {
      /* list all possible characters, similar looking characters and vowels have been removed */
      $possible = 'BCDFGHJKMNPQRSTVWXYZ23456789bcdfghjkmnpqrstvwxyz';
      $code = '';
      $i = 0;
      while ($i < $characters) {
         $code .= substr($possible, mt_rand(0, strlen($possible)-1), 1);
         $i++;
      }
      return $code;
   }

   function CaptchaSecurityImages($width='120',$height='40',$characters='6') {

      $code = $this->generateCode($characters);

      /* font size will be 75% of the image height */
      $font_size = $height * 0.50;
      $image = imagecreate($width, $height) or die('Cannot initialize new GD image stream');

      /* set the colours */
      $background_color = imagecolorallocate($image, 255, 255, 255);

      /* red text */
      //$text_color = imagecolorallocate($image, 220, 10, 10);

      /* black text */
      $text_color = imagecolorallocate($image, 1, 1, 1);

 $rndR = rand(98,198);
 $rndG = rand(98,198);
 $rndB = rand(98,198);
      $noise_color = imagecolorallocate($image, $rndR, $rndG, $rndB);

      /* generate random dots in background */
      for( $i=0; $i<($width*$height)/3; $i++ ) {
         imagefilledellipse($image, mt_rand(0,$width), mt_rand(0,$height), 1, 1, $noise_color);
      }

      /* generate random lines in background */
      for( $i=0; $i<($width*$height)/150; $i++ ) {
         imageline($image, mt_rand(0,$width), mt_rand(0,$height), mt_rand(0,$width), mt_rand(0,$height), $noise_color);
      }

      /* create textbox and add text */
      $textbox = imagettfbbox($font_size, 0, $this->font, $code) or die('Error in imagettfbbox function');
      $x = ($width - $textbox[4])/2;
      $y = ($height - $textbox[5])/2;
      imagettftext($image, $font_size, 0, $x, $y, $text_color, $this->font , $code) or die('Error in imagettftext function');

      // Show the image.
 if (function_exists('imagegif'))
 {
  header('Content-type: image/gif');
  imagegif($image);
 }
 else
 {
  header('Content-type: image/png');
  imagepng($image);
 }

 // Bail out.
 imagedestroy($image);

      $_SESSION['security_code'] = $code;

      die();


   }

}

$width = isset($_GET['width']) && $_GET['height'] < 600 ? $_GET['width'] : '132';
$height = isset($_GET['height']) && $_GET['height'] < 200 ? $_GET['height'] : '36';
$characters = isset($_GET['characters']) && $_GET['characters'] > 2 ? $_GET['characters'] : '6';

$captcha = new CaptchaSecurityImages($width,$height,$characters);

?>
Comments
1 Comments

1 komentar:

untung mujiyono mengatakan...

newbee nyimak

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