Security Code Verification Using PHP

Security code Verification is used for security test to determine whether or not the user is human. Here is a simple security code Verification Script that Generate the code Dynamically.

<?php
$im = ImageCreate(120, 30);  //create image
$white = ImageColorAllocate($im, 255, 255, 255);  //Allocate color for  image
$black = ImageColorAllocate($im, 50, 50, 50);
$string = md5(rand(0,9999));  //Generate a random value and Calculate the md5 hash of the string
//echo $string;
$string=substr($string,1,7); //Return part of a string
$verification = $string;
ImageFill($im, 0, 0, $black); //Fill the Image
ImageString($im, 5, 30, 10, $verification, $white); //Draw the string
Imagejpeg($im, “verify.png”); //Create the Image as ‘png’ format
ImageDestroy($im);  //Destroy the image
?>
<form method=”post” action=”image_verification.php”>
<input type=’hidden’ name=’secretcode’ value=’<?=$verification?>’>
Type Code from Image:
<input type=’text’ name=’code’>
<img src=’verify.png’ border=’1′>
<input type=’submit’ name=’submit’ value=’Submit’>
</form>

<?php
if(isset($_POST['submit']))
{
$code = $_POST['code'];
$secretcode = $_POST['secretcode'];

if($code!=$secretcode){
print “<font color=’red’>Verification failed</font>”;
}
else{
print “<font color=’green’>Verification Success</font>”;
}
}
?>