use GD to randomly generate a image with the code to fill out, and also make a temporary file on the server with the code in it so it can be validated. here is some simple random image generation code:
<?php
$array = array(
'Use PHP!',
'OMG! LOOL!',
'There can be only one true yuri',
'Fwapeh goodness',
'Monkeys will take over!',
'BOWUUUUUUUUUUU!',
'Meh madz PHP site'
);
$text = $array[rand(0,6)];
$height = 30; //h
$width = 300; //w
$im = ImageCreate($width, $height); //make it
$txt = ImageColorAllocate ($im, 0, 0, 0); //black
$bg = ImageColorAllocate ($im, 203, 203, 203); //greyish to match website background color
ImageFill($im, 0, 0, $bg); //fill bg with the greyish
ImageString($im, 5, 5, 6, "$text", $txt); //write the text
header ('Content-type: image/png'); //mime type
ImagePng ($im); //send it to the browser
ImageDestroy($im); //DIEEEEEEE
?>
now, you can take that and modify my random password generator to make the random code:
<?php
srand ((float) microtime() * 10000000);
$array = array_merge(range("a", "z"), range ("0", "9"), range("!", ")"), range("/", "+"), range(",", "/"), range(">", "?"), range("A", "Z"));
$plain = "";
for ($i=1; $i <= 79; $i++) // change the $i <= 79 to $i <= 5 for a 5 charicter password
$plain .= $array[rand(0, 79)];
$pass = md5($plain);
$crypt_pass = crypt($plain);
echo $plain."<br /><br />".$pass."<br /><br />".$crypt_pass;
echo "<br /><br />".pow(79, 79)."<br />^^^ see that number above? thats how many possibilities there are in a 79 charicter password!";
?>
uuh... you will want to make the password smaller then 79 charicters... 😉
also, in the image, draw a bunch of lines but still retaining visibility of the password.
