1 Security Image Menggunakan PHP
Screenshot:
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);
?>
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