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| author | Derek Jones <derek.jones@ellislab.com> | 2011-10-05 20:34:52 +0200 |
|---|---|---|
| committer | Derek Jones <derek.jones@ellislab.com> | 2011-10-05 20:34:52 +0200 |
| commit | 8ede1a2ecbb62577afd32996956c5feaf7ddf9b6 (patch) | |
| tree | 2e960ec3b416b477f40bb546371f2d486f4a22f0 /user_guide/libraries/encryption.html | |
| parent | d1ecd5cd4ae6ab5d37df9fbda14b93977b9e743c (diff) | |
replacing the old HTML user guide with a Sphinx-managed user guide
Diffstat (limited to 'user_guide/libraries/encryption.html')
| -rw-r--r-- | user_guide/libraries/encryption.html | 224 |
1 files changed, 0 insertions, 224 deletions
diff --git a/user_guide/libraries/encryption.html b/user_guide/libraries/encryption.html deleted file mode 100644 index 5c64127cb..000000000 --- a/user_guide/libraries/encryption.html +++ /dev/null @@ -1,224 +0,0 @@ -<!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 2.0.3</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 either compiles -the message using a randomly hashed bitwise XOR encoding scheme, or is 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 be provided with a high degree of security appropriate for storage.</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> - -<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 = $this->encrypt->decode($msg, $key);</code> - - -<h2>$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_CBC</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> - -<h2 id="legacy">$this->encrypt->encode_from_legacy(<kbd>$orig_data</kbd>, <kbd>$legacy_mode</kbd> = MCRYPT_MODE_ECB, <kbd>$key</kbd> = '');</h2> -<p>Enables you to re-encode data that was originally encrypted with CodeIgniter 1.x to be compatible with the Encryption library in CodeIgniter 2.x. It is only - necessary to use this method if you have encrypted data stored permanently such as in a file or database and are on a server that supports Mcrypt. "Light" use encryption - such as encrypted session data or transitory encrypted flashdata require no intervention on your part. However, existing encrypted Sessions will be - destroyed since data encrypted prior to 2.x will not be decoded.</p> - -<p class="important"><strong>Why only a method to re-encode the data instead of maintaining legacy methods for both encoding and decoding?</strong> The algorithms in - the Encryption library have improved in CodeIgniter 2.x both for performance and security, and we do not wish to encourage continued use of the older methods. - You can of course extend the Encryption library if you wish and replace the new methods with the old and retain seamless compatibility with CodeIgniter 1.x - encrypted data, but this a decision that a developer should make cautiously and deliberately, if at all.</p> - -<code>$new_data = $this->encrypt->encode_from_legacy(<kbd>$old_encrypted_string</kbd>);</code> - -<table cellpadding="0" cellspacing="1" border="0" style="width:100%" class="tableborder"> -<tr> - <th>Parameter</th> - <th>Default</th> - <th>Description</th> -</tr> -<tr> - <td class="td"><strong>$orig_data</strong></td> - <td class="td">n/a</td> - <td class="td">The original encrypted data from CodeIgniter 1.x's Encryption library</td> -</tr> -<tr> - <td class="td"><strong>$legacy_mode</strong></td> - <td class="td">MCRYPT_MODE_ECB</td> - <td class="td">The Mcrypt mode that was used to generate the original encrypted data. CodeIgniter 1.x's default was MCRYPT_MODE_ECB, and it will - assume that to be the case unless overridden by this parameter.</td> -</tr> -<tr> - <td class="td"><strong>$key</strong></td> - <td class="td">n/a</td> - <td class="td">The encryption key. This it typically specified in your config file as outlined above.</td> -</tr> -</table> - -</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 - 2011 · <a href="http://ellislab.com/">EllisLab, Inc.</a></p> -</div> - -</body> -</html>
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