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user_guide/helpers/captcha_helper.html
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user_guide/helpers/captcha_helper.html
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<title>CAPTCHA Helper : CodeIgniter User Guide</title>
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<style type='text/css' media='all'>@import url('../userguide.css');</style>
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<link rel='stylesheet' type='text/css' media='all' href='../userguide.css' />
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<script type="text/javascript" src="../nav/nav.js"></script>
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<script type="text/javascript" src="../nav/prototype.lite.js"></script>
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<script type="text/javascript" src="../nav/moo.fx.js"></script>
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<script type="text/javascript" src="../nav/user_guide_menu.js"></script>
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<meta http-equiv='expires' content='-1' />
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<meta http-equiv= 'pragma' content='no-cache' />
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<meta name='robots' content='all' />
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<meta name='author' content='ExpressionEngine Dev Team' />
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<meta name='description' content='CodeIgniter User Guide' />
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</head>
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<body>
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<!-- START NAVIGATION -->
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<div id="nav"><div id="nav_inner"><script type="text/javascript">create_menu('../');</script></div></div>
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<div id="nav2"><a name="top"></a><a href="javascript:void(0);" onclick="myHeight.toggle();"><img src="../images/nav_toggle_darker.jpg" width="154" height="43" border="0" title="Toggle Table of Contents" alt="Toggle Table of Contents" /></a></div>
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<div id="masthead">
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<table cellpadding="0" cellspacing="0" border="0" style="width:100%">
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<tr>
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<td><h1>CodeIgniter User Guide Version 2.1.3</h1></td>
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<td id="breadcrumb_right"><a href="../toc.html">Table of Contents Page</a></td>
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</tr>
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</table>
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</div>
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<!-- END NAVIGATION -->
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<!-- START BREADCRUMB -->
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<table cellpadding="0" cellspacing="0" border="0" style="width:100%">
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<tr>
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<td id="breadcrumb">
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<a href="http://codeigniter.com/">CodeIgniter Home</a> ›
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<a href="../index.html">User Guide Home</a> ›
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CAPTCHA Helper
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</td>
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<td id="searchbox"><form method="get" action="http://www.google.com/search"><input type="hidden" name="as_sitesearch" id="as_sitesearch" value="codeigniter.com/user_guide/" />Search User Guide <input type="text" class="input" style="width:200px;" name="q" id="q" size="31" maxlength="255" value="" /> <input type="submit" class="submit" name="sa" value="Go" /></form></td>
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</tr>
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</table>
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<!-- END BREADCRUMB -->
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<br clear="all" />
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<!-- START CONTENT -->
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<div id="content">
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<h1>CAPTCHA Helper</h1>
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<p>The CAPTCHA Helper file contains functions that assist in creating CAPTCHA images.</p>
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<h2>Loading this Helper</h2>
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<p>This helper is loaded using the following code:</p>
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<code>$this->load->helper('captcha');</code>
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<p>The following functions are available:</p>
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<h2>create_captcha(<var>$data</var>)</h2>
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<p>Takes an array of information to generate the CAPTCHA as input and creates the image to your specifications, returning an array of associative data about the image.</p>
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<code>[array]<br />
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(<br />
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'image' => IMAGE TAG<br />
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'time' => TIMESTAMP (in microtime)<br />
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'word' => CAPTCHA WORD<br />
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)</code>
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<p>The "image" is the actual image tag:
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<code><img src="http://example.com/captcha/12345.jpg" width="140" height="50" /></code></p>
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<p>The "time" is the micro timestamp used as the image name without the file
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extension. It will be a number like this: 1139612155.3422</p>
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<p>The "word" is the word that appears in the captcha image, which if not
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supplied to the function, will be a random string.</p>
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<h3>Using the CAPTCHA helper</h3>
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<p>Once loaded you can generate a captcha like this:</p>
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<code>$vals = array(<br />
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'word' => 'Random word',<br />
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'img_path' => './captcha/',<br />
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'img_url' => 'http://example.com/captcha/',<br />
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'font_path' => './path/to/fonts/texb.ttf',<br />
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'img_width' => '150',<br />
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'img_height' => 30,<br />
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'expiration' => 7200<br />
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);<br />
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<br />
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$cap = create_captcha($vals);<br />
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echo $cap['image'];</code>
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<ul>
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<li>The captcha function requires the GD image library.</li>
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<li>Only the img_path and img_url are required.</li>
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<li>If a "word" is not supplied, the function will generate a random
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ASCII string. You might put together your own word library that
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you can draw randomly from.</li>
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<li>If you do not specify a path to a TRUE TYPE font, the native ugly GD
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font will be used.</li>
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<li>The "captcha" folder must be writable (666, or 777)</li>
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<li>The "expiration" (in seconds) signifies how long an image will
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remain in the captcha folder before it will be deleted. The default
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is two hours.</li>
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</ul>
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<h3>Adding a Database</h3>
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<p>In order for the captcha function to prevent someone from submitting, you will need
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to add the information returned from <kbd>create_captcha()</kbd> function to your database.
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Then, when the data from the form is submitted by the user you will need to verify
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that the data exists in the database and has not expired.</p>
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<p>Here is a table prototype:</p>
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<code>CREATE TABLE captcha (<br />
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captcha_id bigint(13) unsigned NOT NULL auto_increment,<br />
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captcha_time int(10) unsigned NOT NULL,<br />
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ip_address varchar(16) default '0' NOT NULL,<br />
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word varchar(20) NOT NULL,<br />
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PRIMARY KEY `captcha_id` (`captcha_id`),<br />
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KEY `word` (`word`)<br />
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);</code>
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<p>Here is an example of usage with a database. On the page where the CAPTCHA will be shown you'll have something like this:</p>
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<code>$this->load->helper('captcha');<br />
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$vals = array(<br />
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'img_path' => './captcha/',<br />
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'img_url' => 'http://example.com/captcha/'<br />
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);<br />
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<br />
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$cap = create_captcha($vals);<br />
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<br />
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$data = array(<br />
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'captcha_time' => $cap['time'],<br />
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'ip_address' => $this->input->ip_address(),<br />
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'word' => $cap['word']<br />
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);<br />
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<br />
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$query = $this->db->insert_string('captcha', $data);<br />
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$this->db->query($query);<br />
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<br />
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echo 'Submit the word you see below:';<br />
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echo $cap['image'];<br />
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echo '<input type="text" name="captcha" value="" />';</code>
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<p>Then, on the page that accepts the submission you'll have something like this:</p>
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<code>// First, delete old captchas<br />
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$expiration = time()-7200; // Two hour limit<br />
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$this->db->query("DELETE FROM captcha WHERE captcha_time < ".$expiration); <br />
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<br />
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// Then see if a captcha exists:<br />
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$sql = "SELECT COUNT(*) AS count FROM captcha WHERE word = ? AND ip_address = ? AND captcha_time > ?";<br />
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$binds = array($_POST['captcha'], $this->input->ip_address(), $expiration);<br />
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$query = $this->db->query($sql, $binds);<br />
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$row = $query->row();<br />
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<br />
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if ($row->count == 0)<br />
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{<br />
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echo "You must submit the word that appears in the image";<br />
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}</code>
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</div>
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<!-- END CONTENT -->
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<div id="footer">
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<p>
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Previous Topic: <a href="array_helper.html">Array Helper</a>
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·
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<a href="#top">Top of Page</a> ·
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<a href="../index.html">User Guide Home</a> ·
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Next Topic: <a href="cookie_helper.html">Cookie Helper</a></p>
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<p><a href="http://codeigniter.com">CodeIgniter</a> · Copyright © 2006 - 2012 · <a href="http://ellislab.com/">EllisLab, Inc.</a></p>
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</div>
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</body>
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</html>
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