Captcha

<?php

session_start();

function genPWD ($int_min, $int_max=0) {
	mt_srand();
	if ($int_max != 0) $longueur = mt_rand($int_max, $int_min);
	else $longueur = $int_min;

	$mdp = '';
	for($i=0; $i<$longueur; $i++){
		$quoi= mt_rand(1,3);
		switch($quoi){
			case 1: $mdp .= mt_rand(0,9); break;
			case 2: $mdp .= chr(mt_rand(65,90)); break;
			case 3: $mdp .= chr(mt_rand(97,122)); break;
		}
	}
	return $mdp;
}

function generate_captcha()
{
	putenv('GDFONTPATH=' . realpath('.'));

	$pwd = array();
	$final = array();

	mt_srand();
	for($i=0;$i<mt_rand(500,1000);$i++)
	{
		$pwd[] = genPWD(6,8);
	}

	while(count($final)<6)
	{
		mt_srand();
		$value = mt_rand(0,count($pwd));
		if(!in_array($pwd[$value],$final))
		{
			$final[] = $pwd[$value];
		}
	}

	mt_srand();
	$nb = mt_rand(0,5);
	$texte = 'Veuillez choisir ';
	$texte2 = 'le code écrit en rouge.';
	$img = imagecreate(220,150);
	$bg = imagecolorallocate($img,255,255,255);
	$txt = imagestring($img,5,10,10,$texte,imagecolorallocate($img,0,0,0));
	$txt = imagestring($img,5,10,23,$texte2,imagecolorallocate($img,0,0,0));
	$i = 0;	
	$font = 'kmkdspt';
	
	foreach($final as $key => $value)
	{
		if($key == $nb)
		{
			$color = imagecolorallocate($img,200,0,0);
			$return = $value;
		}
		else
		{
			$color = imagecolorallocate($img,0,0,0);
		}

		if( ($i%2) == 0)
		{
			$txt = imagettftext($img,14,15,20,80+($i*13),$color,$font,$value);
		}
		else
		{
			$txt = imagettftext($img,14,15,110,80+(($i-1)*13),$color,$font,$value);
		}

		$i++;
	}

	imagepng($img);	
	return $return;
}
$_SESSION['code'] = generate_captcha();
?>