Captcha

[CrOuZ]

Hi , i need to any idea for captcha secure form . my idea : i have ( 0 - 9 ) images . ( example : 0.gif - 1.gif - 2.gif - 3.gif - 4.gif - - - - - - 9.gif ) in my images folder . now how to show 5 random number for secure form ?? example : 34956 <= this : (3.gif)(4.gif)(9.gif)(5.gif)(6.gif) . for each refresh page or form change secure number . how to ??

[harmor]

I suppose you can call five random numbers at the start of the conditional.
I'm assuming you are using IF Conditionals to separate different portions of your site.

<?php
session_start();

if($_GET['var'] == "form")
{
    unset($_SESSION['image1'],$_SESSION['image2'],$_SESSION['image3'],$_SESSION['image4'],$_SESSION['image5']);

$_SESSION['image1'] = rand(0,9);
$_SESSION['image2'] = rand(0,9);
$_SESSION['image3'] = rand(0,9);
$_SESSION['image4'] = rand(0,9);
$_SESSION['image5'] = rand(0,9);



echo "<form action='?var=postform' method='post'>
  <img src='".$_SESSION['image1'].".gif' /><img src='".$_SESSION['image2'].".gif' /><img src='".$_SESSION['image3'].".gif'  /><img src='".$_SESSION['image4'].".gif' /><img src='".$_SESSION['image5'].".gif' /> <input type="text" name="captcha" />
<input type="submit" value="Submit" />
</form>";
}

if($_GET['var'] == "postform")
{

$verificationNumbers = $_SESSION['image1'].$_SESSION['image2'].$_SESSION['image3'].$_SESSION['image4'].$_SESSION['image5'];

if($_POST['captcha'] != $verificationNumbers)
{
    die('Verification Does Not Match');
}
}

?>

This is untested.

[bradgrafelman]

Simplest way I could think of doing it was taking a random number from [man]mt_rand/man, casting it into a string, and then using the string property in PHP that allows you to access each character individually as if it was an array (similar to an NTCA in C/C++).

Example code:

$num = (string)mt_rand(10000,99999);

for($i = 0; $i < strlen($num); $i++)
    echo $test[$i] . ".gif\n";

[Weedpacket]

I'd suggest rendering it as one single image. The way you're writing it, instead of seeing 34956 the spambot will see <img src='3.gif' /><img src='4.gif' /><img src='9.gif' /><img src='5.gif' /><img src='6.gif' />, and it wouldn't take any fancy OCR software for the bot to figure out what the code was.

[bradgrafelman]

And if you really wanted to get fancy, you could make the filenames of the integers be the [man]md5/man hash of that integer, so 1.gif would instead be c4ca4238a0b923820dcc509a6f75849b.gif and so on.

[harmor]

bradgrafelman;10914862 wrote:

And if you really wanted to get fancy, you could make the filenames of the integers be the [man]md5/man hash of that integer, so 1.gif would instead be c4ca4238a0b923820dcc509a6f75849b.gif and so on.

Go one step further and do this

$salt = "anything";
md5($imageX . $salt);

[bradgrafelman]

If you really wanted to prevent simple text-reading bots to guess the numbers, you could do <img src="captcha.php">, store the numbers in a session variable to be checked later, and use gd to dynamically compile the .gif's together into one image that is displayed. :p

[CrOuZ]

thanks for reply ! If save number in mysql database and than md5 and show in page . this way will be high secure .

<img src="?images=security&action=image&num_id=6eb1cc4a3441e8b38b0b039e4e061257" >

for each refresh page delete unmber as mysql if security number = num_Id . and if security number != true delete old number and show new number with this error : your security number is false please try again . your advice ? and how to .

[khaine]

You could just use reCaptcha. It's the one I use when I need input verification.

[kender]

or SecurImage which is also nice and customizable