411 REFERENCE · Wikibooks
CAPTCHA/Integration/Images and PHP
Reference material by Wikibooks contributors. This retains its source identity and is not 411 news reporting.
image.php
<?php
$width = 50;
$height = 25;
session_start();
unset($_SESSION['code']); // added security
$len = 6; // you can change this
mt_srand(time());
// generate random values
$r = 0;
$g = 0;
$b = 0;
$r = mt_rand(80, 255);
$g = mt_rand(80, 255);
$b = mt_rand(80, 255);
$s = 0;
$h = 0;
$c = 0;
$s = mt_rand(0, 80);
$h = mt_rand(80, 80);
$c = mt_rand(80, 100);
$code = mt_rand(100000,999999);
$size = 0.75 * 40;
$image = imagecreate($width, $height) or die("couldn't generate image");
$bg = imagecolorallocate($image, $s, $h, $c);
$c1 = imagecolorallocate($image, $r, $g, $b);
imagestring($image,2,3,3,$code,$c1);
header('Content-Type: image/png');
imagepng($image);
$_SESSION=$code;
imagedestroy($image);
?>
This is the CAPTCHA itself.
form.php
<?php
echo "<img src='/image.php' /><input name=code />";
?>
This is the form code.
validate.php
<?php
session_start();
if ($_POST['code'] != $_SESSION['code']) {
//fail
}
?>
This will validate the CAPTCHA.