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CAPTCHA

This is a simple captcha that generates an image based on a random string stored in a database. MySQL required.

Submitted By: Styx

Actions:

Rating:

Views: 2,763

Language: PHP

Last Modified: May 2, 2007

Instructions:
Create the following SQL table:
CREATE TABLE captcha (
confirm_id char(32) DEFAULT '' NOT NULL,
session_id char(32) DEFAULT '' NOT NULL,
code char(8) DEFAULT '' NOT NULL,
PRIMARY KEY (session_id,confirm_id)
);

Modify the settings in the script.

This script uses TTF fonts to display the code. You can upload your own fonts to use. Just be sure to change $font_dir to wherever your fonts are stored. (A default font without rotation is used if none are available.)

There are two pages to this snippet. The first half is the captcha script. The second half is an example test page. Use the test page to understand how to implement the captcha.

This script originally inspired by the Anti-Spam ACP mod by EXreaction:
http://www.phpbb.com/community/viewtopic.php?t=465600

Snippet

<?php
//
// Settings
//
$dbhost = 'localhost';
$dbuser = 'username';
$dbpass = 'password';
$database = 'database';
$min_char = 4;
$max_char = 8;
$font_dir = './*.ttf';
//
// Initial start
//
mysql_connect($dbhost, $dbuser, $dbpass);
mysql_select_db($database);
session_start();
//
// Initiate image
//
header("content-type: image/png");
header("Cache-control: no-cache, no-store");
$width = rand(200, 300);
$height = rand(50, 70);
$img = imagecreate($width, $height);
$background = imagecolorallocate($img, rand(200, 255), rand(200, 255), rand(200, 255));
//
// Compile code
//
$array = array();
for ($i = 0; $i < $max_char; $i++)
{
$alpha = chr(rand(1, 26) + 64);
$numeric = rand(0, 9);
$array[] = (rand(0, 1) == 0 || count($array) < $min_char) ? ((rand(0, 1) == 0) ? $alpha : $numeric) : '';
}
$code = str_replace('0', 'Z', implode('', $array));
//
// Query database
//
$confirm_id = (eregi('^[a-z0-9]{32}$', $_GET['id'])) ? $_GET['id'] : md5(uniqid($_SERVER['REMOTE_ADDR']));
$session_id = (eregi("^[a-z0-9]{32}$", session_id())) ? session_id() : '';
mysql_query("DELETE FROM captcha WHERE session_id = '$session_id'");
mysql_query("INSERT INTO captcha (confirm_id, session_id, code) VALUES ('$confirm_id', '$session_id', '$code')");
//
// Create background
//
for ($i = 0; $i < rand(5, 20); $i++)
{
$color = imagecolorallocate($img, rand(0, 255), rand(0, 255), rand(0, 255));
$loc_x = rand(-100, $width + 100);
$loc_y = rand(-50, $height + 50);
$end_x = rand(-100, $width + 100);
$end_y = rand(-50, $height + 50);
// Background shapes
$shape = rand(1, 3);
switch ($shape)
{
case 1:
// Draw an ellipse
imageellipse($img, $loc_x, $loc_y, rand(100, 400), rand(50, 400), $color);
break;
case 2:
// Draw a rectangle
imagerectangle($img, $loc_x, $loc_y, $end_x, $end_y, $color);
break;
case 3:
// Draw a line
imageline($img, $loc_x, $loc_y, $end_x, $end_y, $color);
break;
}
}
//
// Compile image
//
$x_move = $width / (strlen($code) + 1);
$current_pos = rand(0, $x_move / 2);
$less_rotate = array('N', 'Z', '6', '9');
for ($i = 0; $i < strlen($code); $i++)
{
$size = rand(15, 20);
$angle = (in_array($code[$i], $less_rotate)) ? rand(-15, 15) : rand(-30, 30);
$x_pos = $current_pos + rand($size + 1, $x_move);
$y_pos = $height/2 + rand(-8, 8);
$current_pos = $x_pos;
$fonts = glob($font_dir);
$font = $fonts[array_rand($fonts)];
$color = imagecolorallocate($img, rand(0, 127), rand(0, 127), rand(0, 127));
if (!empty($font))
imagettftext($img, $size, $angle, $x_pos, $y_pos, $color, $font, $code[$i]);
else
imagestring($img, 5, $x_pos, $y_pos, $code[$i], $color);
}
//
// Create image
//
imagepng($img);
imagedestroy($img);
/* ------ MySQL Query ------
CREATE TABLE captcha (
confirm_id char(32) DEFAULT '' NOT NULL,
session_id char(32) DEFAULT '' NOT NULL,
code char(8) DEFAULT '' NOT NULL,
PRIMARY KEY (session_id,confirm_id)
);
*/
?>
### TEST PAGE ###
<?php
mysql_connect('localhost', 'username', 'password');
mysql_select_db('database');
session_start();
if (isset($_POST['submit']))
{
$confirm_id = (eregi('^[a-z0-9]{32}$', $_POST['confirm_id'])) ? $_POST['confirm_id'] : '';
$result = mysql_query("SELECT * FROM captcha WHERE confirm_id = '$confirm_id' LIMIT 1");
$row = mysql_fetch_assoc($result);
if (!$row || $_POST['confirm'] !== $row['code'])
{
echo '<b>Invalid Code:</b>';
}
else
{
$session_id = (eregi("^[a-z0-9]{32}$", session_id())) ? session_id() : '';
mysql_query("DELETE FROM captcha WHERE session_id = '$session_id'");
session_destroy();
echo '<b>Valid:</b>';
}
echo $_POST['confirm'] . '|' . $row['code'] . '<br />';
}
$confirm_id = md5(uniqid($_SERVER['REMOTE_ADDR']));
?>
<img src="captcha.php?id=<?php echo $confirm_id; ?>">
<form method="post">
<input type="hidden" name="confirm_id" value="<?php echo $confirm_id; ?>">
<input type="text" name="confirm" size="30">
<input type="submit" name="submit" value="Submit">
</form>

Copy & Paste

<?php
//
// Settings
//
$dbhost = 'localhost';
$dbuser = 'username';
$dbpass = 'password';
$database = 'database';

$min_char = 4;
$max_char = 8;
$font_dir = './*.ttf';

//
// Initial start
//
mysql_connect($dbhost, $dbuser, $dbpass);
mysql_select_db($database);

session_start();

//
// Initiate image
//
header("content-type: image/png");
header("Cache-control: no-cache, no-store");

$width = rand(200, 300);
$height = rand(50, 70);
$img = imagecreate($width, $height);
$background = imagecolorallocate($img, rand(200, 255), rand(200, 255), rand(200, 255));

//
// Compile code
//
$array = array();
for ($i = 0; $i < $max_char; $i++)
{
  $alpha = chr(rand(1, 26) + 64);
  $numeric = rand(0, 9);

$array[] = (rand(0, 1) == 0 || count($array) < $min_char) ? ((rand(0, 1) == 0) ? $alpha : $numeric) : '';
}

$code = str_replace('0', 'Z', implode('', $array));

//
// Query database
//
$confirm_id = (eregi('^[a-z0-9]{32}$', $_GET['id'])) ? $_GET['id'] : md5(uniqid($_SERVER['REMOTE_ADDR']));
$session_id = (eregi("^[a-z0-9]{32}$", session_id())) ? session_id() : '';
mysql_query("DELETE FROM captcha WHERE session_id = '$session_id'");
mysql_query("INSERT INTO captcha (confirm_id, session_id, code) VALUES ('$confirm_id', '$session_id', '$code')");

//
// Create background
//
for ($i = 0; $i < rand(5, 20); $i++)
{
  $color = imagecolorallocate($img, rand(0, 255), rand(0, 255), rand(0, 255));
  $loc_x = rand(-100, $width + 100);
  $loc_y = rand(-50, $height + 50);
  $end_x = rand(-100, $width + 100);
  $end_y = rand(-50, $height + 50);

// Background shapes
  $shape = rand(1, 3);
  switch ($shape)
  {
    case 1:
      // Draw an ellipse
      imageellipse($img, $loc_x, $loc_y, rand(100, 400), rand(50, 400), $color);
    break;

case 2:
      // Draw a rectangle
      imagerectangle($img, $loc_x, $loc_y, $end_x, $end_y, $color);
    break;

case 3:
      // Draw a line
      imageline($img, $loc_x, $loc_y, $end_x, $end_y, $color);
    break;
  }
}

//
// Compile image
//
$x_move = $width / (strlen($code) + 1);
$current_pos = rand(0, $x_move / 2);

$less_rotate = array('N', 'Z', '6', '9');
for ($i = 0; $i < strlen($code); $i++)
{
  $size = rand(15, 20);
  $angle = (in_array($code[$i], $less_rotate)) ? rand(-15, 15) : rand(-30, 30);

$x_pos = $current_pos + rand($size + 1, $x_move);
  $y_pos = $height/2 + rand(-8, 8);
  $current_pos = $x_pos;

$fonts = glob($font_dir);
  $font = $fonts[array_rand($fonts)];
  $color = imagecolorallocate($img, rand(0, 127), rand(0, 127), rand(0, 127));

if (!empty($font))
    imagettftext($img, $size, $angle, $x_pos, $y_pos, $color, $font, $code[$i]);
  else
    imagestring($img, 5, $x_pos, $y_pos, $code[$i], $color);
}

//
// Create image
//
imagepng($img);
imagedestroy($img);

/* ------ MySQL Query ------
CREATE TABLE captcha (
confirm_id char(32) DEFAULT '' NOT NULL,
session_id char(32) DEFAULT '' NOT NULL,
code char(8) DEFAULT '' NOT NULL, 
PRIMARY KEY  (session_id,confirm_id)
);
*/
?>

### TEST PAGE ###
<?php
mysql_connect('localhost', 'username', 'password');
mysql_select_db('database');

session_start();

if (isset($_POST['submit']))
{
  $confirm_id = (eregi('^[a-z0-9]{32}$', $_POST['confirm_id'])) ? $_POST['confirm_id'] : '';
  $result = mysql_query("SELECT * FROM captcha WHERE confirm_id = '$confirm_id' LIMIT 1");
  $row = mysql_fetch_assoc($result);

if (!$row || $_POST['confirm'] !== $row['code'])
  {
    echo '<b>Invalid Code:</b>';
  }
  else
  {
    $session_id = (eregi("^[a-z0-9]{32}$", session_id())) ? session_id() : '';
    mysql_query("DELETE FROM captcha WHERE session_id = '$session_id'");
    session_destroy();

echo '<b>Valid:</b>';
  }

echo $_POST['confirm'] . '|' . $row['code'] . '<br />';
}

$confirm_id = md5(uniqid($_SERVER['REMOTE_ADDR']));

?>
<img src="captcha.php?id=<?php echo $confirm_id; ?>">
<form method="post">
<input type="hidden" name="confirm_id" value="<?php echo $confirm_id; ?>">
<input type="text" name="confirm" size="30">
<input type="submit" name="submit" value="Submit">
</form>