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***drdebcol*** · 05-24-2010, 11:40 PM

This is simple Captcha script. You have comments inside the code and that enables you to manipulate with different Captcha data. You can change letters, digits, size of image, background color etc.
Here is the code :

PHP Code:

<?php
session_start();
$mix = "ABCDEFGHJKLMNPQRSTUVWXYZ23456789"; // Characters to use in the captcha I have taken out 0,O,1,l,I to avoid confusion
$rand = substr(str_shuffle($mix), 0, 5); // Generate a random 5 character string from the $mix
$_SESSION['captcha_image_value'] = md5($rand); // Assign the randomly generated string to a session variable so we may reference it later

$image = imagecreate(60, 30); // Create a 60 x 30 image
$bgColor = imagecolorallocate ($image, 41, 41, 41); // Assign a background color using the RGB values 41, 41 and 41
$textColorV = imagecolorallocate ($image, 175, 175, 175);
$lineColorV = imagecolorallocate ($image, 240, 0, 0);
imageline($image,0,12,60,20,$lineColorV); // Draw a line from (0,12) to (60,20) of color $line color
imageline($image,0,20,60,12,$lineColorV);
imagestring ($image, 5, 5, 8, $rand, $textColorV); // Write the string to the image

// Some headers to prevent the image from being cached, thus ensuring the browser gets a new image every time the page is loaded
header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");
header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
header("Cache-Control: no-store, no-cache, must-revalidate");
header("Cache-Control: post-check=0, pre-check=0", false);
header("Pragma: no-cache");
header('Content-type: image/png'); // Makes browser recognize this script as an image

imagepng($image);
imagedestroy($image);
?>

ajcis55 · (This post was last modified: 05-25-2010 03:09 AM by ajcis55.)

Easy enough. For those confused about how to verify the user entered the correct captcha, you'll want to do something like this in your form submission:

Code:

<?php

session_start();

if(md5(txtCaptcha.value) ==  $_SESSION['captcha_image_value'])

    echo "Correct captcha";

else

    echo "Invalid captcha.";

?>

***drdebcol*** · 05-25-2010, 03:45 AM

Yeah very good. This is because in the code we have :

Code:

$_SESSION['captcha_image_value'] = md5($rand);

That is using of md5 function on rand.
THX for reply !