182 lines
7.8 KiB
HTML
182 lines
7.8 KiB
HTML
|
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||
|
|
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
|
||
|
|
<head>
|
||
|
|
|
||
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
|
||
|
|
<title>Encryption Class : CodeIgniter User Guide</title>
|
||
|
|
|
||
|
|
<style type='text/css' media='all'>@import url('../userguide.css');</style>
|
||
|
|
<link rel='stylesheet' type='text/css' media='all' href='../userguide.css' />
|
||
|
|
|
||
|
|
<script type="text/javascript" src="../nav/nav.js"></script>
|
||
|
|
<script type="text/javascript" src="../nav/prototype.lite.js"></script>
|
||
|
|
<script type="text/javascript" src="../nav/moo.fx.js"></script>
|
||
|
|
<script type="text/javascript" src="../nav/user_guide_menu.js"></script>
|
||
|
|
|
||
|
|
<meta http-equiv='expires' content='-1' />
|
||
|
|
<meta http-equiv= 'pragma' content='no-cache' />
|
||
|
|
<meta name='robots' content='all' />
|
||
|
|
<meta name='author' content='ExpressionEngine Dev Team' />
|
||
|
|
<meta name='description' content='CodeIgniter User Guide' />
|
||
|
|
|
||
|
|
</head>
|
||
|
|
<body>
|
||
|
|
|
||
|
|
<!-- START NAVIGATION -->
|
||
|
|
<div id="nav"><div id="nav_inner"><script type="text/javascript">create_menu('../');</script></div></div>
|
||
|
|
<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>
|
||
|
|
<div id="masthead">
|
||
|
|
<table cellpadding="0" cellspacing="0" border="0" style="width:100%">
|
||
|
|
<tr>
|
||
|
|
<td><h1>CodeIgniter User Guide Version 1.7.3</h1></td>
|
||
|
|
<td id="breadcrumb_right"><a href="../toc.html">Table of Contents Page</a></td>
|
||
|
|
</tr>
|
||
|
|
</table>
|
||
|
|
</div>
|
||
|
|
<!-- END NAVIGATION -->
|
||
|
|
|
||
|
|
|
||
|
|
<!-- START BREADCRUMB -->
|
||
|
|
<table cellpadding="0" cellspacing="0" border="0" style="width:100%">
|
||
|
|
<tr>
|
||
|
|
<td id="breadcrumb">
|
||
|
|
<a href="http://codeigniter.com/">CodeIgniter Home</a> ›
|
||
|
|
<a href="../index.html">User Guide Home</a> ›
|
||
|
|
Encryption Class
|
||
|
|
</td>
|
||
|
|
<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>
|
||
|
|
</tr>
|
||
|
|
</table>
|
||
|
|
<!-- END BREADCRUMB -->
|
||
|
|
|
||
|
|
<br clear="all" />
|
||
|
|
|
||
|
|
|
||
|
|
<!-- START CONTENT -->
|
||
|
|
<div id="content">
|
||
|
|
|
||
|
|
|
||
|
|
<h1>Encryption Class</h1>
|
||
|
|
|
||
|
|
<p>The Encryption Class provides two-way data encryption. It uses a scheme that pre-compiles
|
||
|
|
the message using a randomly hashed bitwise XOR encoding scheme, which is then encrypted using
|
||
|
|
the Mcrypt library. If Mcrypt is not available on your server the encoded message will
|
||
|
|
still provide a reasonable degree of security for encrypted sessions or other such "light" purposes.
|
||
|
|
If Mcrypt is available, you'll effectively end up with a double-encrypted message string, which should
|
||
|
|
provide a very high degree of security.</p>
|
||
|
|
|
||
|
|
|
||
|
|
<h2>Setting your Key</h2>
|
||
|
|
|
||
|
|
<p>A <em>key</em> is a piece of information that controls the cryptographic process and permits an encrypted string to be decoded.
|
||
|
|
In fact, the key you chose will provide the <strong>only</strong> means to decode data that was encrypted with that key,
|
||
|
|
so not only must you choose the key carefully, you must never change it if you intend use it for persistent data.</p>
|
||
|
|
|
||
|
|
<p>It goes without saying that you should guard your key carefully.
|
||
|
|
Should someone gain access to your key, the data will be easily decoded. If your server is not totally under your control
|
||
|
|
it's impossible to ensure key security so you may want to think carefully before using it for anything
|
||
|
|
that requires high security, like storing credit card numbers.</p>
|
||
|
|
|
||
|
|
<p>To take maximum advantage of the encryption algorithm, your key should be 32 characters in length (128 bits).
|
||
|
|
The key should be as random a string as you can concoct, with numbers and uppercase and lowercase letters.
|
||
|
|
Your key should <strong>not</strong> be a simple text string. In order to be cryptographically secure it
|
||
|
|
needs to be as random as possible.</p>
|
||
|
|
|
||
|
|
<p>Your key can be either stored in your <dfn>application/config/config.php</dfn>, or you can design your own
|
||
|
|
storage mechanism and pass the key dynamically when encoding/decoding.</p>
|
||
|
|
|
||
|
|
<p>To save your key to your <dfn>application/config/config.php</dfn>, open the file and set:</p>
|
||
|
|
<code>$config['encryption_key'] = "YOUR KEY";</code>
|
||
|
|
|
||
|
|
|
||
|
|
<h2>Message Length</h2>
|
||
|
|
|
||
|
|
<p>It's important for you to know that the encoded messages the encryption function generates will be approximately 2.6 times longer than the original
|
||
|
|
message. For example, if you encrypt the string "my super secret data", which is 21 characters in length, you'll end up
|
||
|
|
with an encoded string that is roughly 55 characters (we say "roughly" because the encoded string length increments in
|
||
|
|
64 bit clusters, so it's not exactly linear). Keep this information in mind when selecting your data storage mechanism. Cookies,
|
||
|
|
for example, can only hold 4K of information.</p>
|
||
|
|
|
||
|
|
|
||
|
|
<h2>Initializing the Class</h2>
|
||
|
|
|
||
|
|
<p>Like most other classes in CodeIgniter, the Encryption class is initialized in your controller using the <dfn>$this->load->library</dfn> function:</p>
|
||
|
|
|
||
|
|
<code>$this->load->library('encrypt');</code>
|
||
|
|
<p>Once loaded, the Encrypt library object will be available using: <dfn>$this->encrypt</dfn></p>
|
||
|
|
|
||
|
|
|
||
|
|
<h2>$this->encrypt->encode()</h2>
|
||
|
|
|
||
|
|
<p>Performs the data encryption and returns it as a string. Example:</p>
|
||
|
|
<code>
|
||
|
|
$msg = 'My secret message';<br />
|
||
|
|
<br />
|
||
|
|
$encrypted_string = $this->encrypt->encode($msg);</code>
|
||
|
|
|
||
|
|
<p>You can optionally pass your encryption key via the second parameter if you don't want to use the one in your config file:</p>
|
||
|
|
|
||
|
|
<code>
|
||
|
|
$msg = 'My secret message';<br />
|
||
|
|
$key = 'super-secret-key';<br />
|
||
|
|
<br />
|
||
|
|
$encrypted_string = $this->encrypt->encode($msg, $key);</code>
|
||
|
|
|
||
|
|
|
||
|
|
<h2>$this->encrypt->decode()</h2>
|
||
|
|
|
||
|
|
<p>Decrypts an encoded string. Example:</p>
|
||
|
|
|
||
|
|
<code>
|
||
|
|
$encrypted_string = 'APANtByIGI1BpVXZTJgcsAG8GZl8pdwwa84';<br />
|
||
|
|
<br />
|
||
|
|
$plaintext_string = $this->encrypt->decode($encrypted_string);</code>
|
||
|
|
|
||
|
|
|
||
|
|
<h2>$this->encrypt->set_cipher();</h2>
|
||
|
|
|
||
|
|
<p>Permits you to set an Mcrypt cipher. By default it uses <samp>MCRYPT_RIJNDAEL_256</samp>. Example:</p>
|
||
|
|
<code>$this->encrypt->set_cipher(MCRYPT_BLOWFISH);</code>
|
||
|
|
<p>Please visit php.net for a list of <a href="http://php.net/mcrypt">available ciphers</a>.</p>
|
||
|
|
|
||
|
|
<p>If you'd like to manually test whether your server supports Mcrypt you can use:</p>
|
||
|
|
<code>echo ( ! function_exists('mcrypt_encrypt')) ? 'Nope' : 'Yup';</code>
|
||
|
|
|
||
|
|
|
||
|
|
<h2>$this->encrypt->set_mode();</h2>
|
||
|
|
|
||
|
|
<p>Permits you to set an Mcrypt mode. By default it uses <samp>MCRYPT_MODE_ECB</samp>. Example:</p>
|
||
|
|
<code>$this->encrypt->set_mode(MCRYPT_MODE_CFB);</code>
|
||
|
|
<p>Please visit php.net for a list of <a href="http://php.net/mcrypt">available modes</a>.</p>
|
||
|
|
|
||
|
|
|
||
|
|
<h2>$this->encrypt->sha1();</h2>
|
||
|
|
<p>SHA1 encoding function. Provide a string and it will return a 160 bit one way hash. Note: SHA1, just like MD5 is non-decodable. Example:</p>
|
||
|
|
<code>$hash = $this->encrypt->sha1('Some string');</code>
|
||
|
|
|
||
|
|
<p>Many PHP installations have SHA1 support by default so if all you need is to encode a hash it's simpler to use the native
|
||
|
|
function:</p>
|
||
|
|
|
||
|
|
<code>$hash = sha1('Some string');</code>
|
||
|
|
|
||
|
|
<p>If your server does not support SHA1 you can use the provided function.</p>
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
</div>
|
||
|
|
<!-- END CONTENT -->
|
||
|
|
|
||
|
|
|
||
|
|
<div id="footer">
|
||
|
|
<p>
|
||
|
|
Previous Topic: <a href="email.html">Email Class</a>
|
||
|
|
·
|
||
|
|
<a href="#top">Top of Page</a> ·
|
||
|
|
<a href="../index.html">User Guide Home</a> ·
|
||
|
|
Next Topic: <a href="file_uploading.html">File Uploading Class</a>
|
||
|
|
</p>
|
||
|
|
<p><a href="http://codeigniter.com">CodeIgniter</a> · Copyright © 2006-2010 · <a href="http://ellislab.com/">Ellislab, Inc.</a></p>
|
||
|
|
</div>
|
||
|
|
|
||
|
|
</body>
|
||
|
|
</html>
|