diff options
Diffstat (limited to 'user_guide/libraries/encryption.html')
| -rw-r--r-- | user_guide/libraries/encryption.html | 362 |
1 files changed, 181 insertions, 181 deletions
diff --git a/user_guide/libraries/encryption.html b/user_guide/libraries/encryption.html index 092dad2ac..a0733ab19 100644 --- a/user_guide/libraries/encryption.html +++ b/user_guide/libraries/encryption.html @@ -1,182 +1,182 @@ -<!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</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 © 2006-2008 · <a href="http://ellislab.com/">Ellislab, Inc.</a></p>
-</div>
-
-</body>
+<!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</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 © 2006-2008 · <a href="http://ellislab.com/">Ellislab, Inc.</a></p> +</div> + +</body> </html>
\ No newline at end of file |