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<title>Opens the module of the algorithm and the mode to be used</title>
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<h1 class="refname">mcrypt_module_open</h1>
<p class="verinfo">(PHP 4 >= 4.0.2, PHP 5)</p><p class="refpurpose"><span class="refname">mcrypt_module_open</span> — <span class="dc-title">Opens the module of the algorithm and the mode to be used</span></p>
</div>
<div class="refsect1 description" id="refsect1-function.mcrypt-module-open-description">
<h3 class="title">Description</h3>
<div class="methodsynopsis dc-description">
<span class="type">resource</span> <span class="methodname"><strong>mcrypt_module_open</strong></span>
( <span class="methodparam"><span class="type">string</span> <code class="parameter">$algorithm</code></span>
, <span class="methodparam"><span class="type">string</span> <code class="parameter">$algorithm_directory</code></span>
, <span class="methodparam"><span class="type">string</span> <code class="parameter">$mode</code></span>
, <span class="methodparam"><span class="type">string</span> <code class="parameter">$mode_directory</code></span>
)</div>
<p class="para rdfs-comment">
This function opens the module of the algorithm and the mode to be used.
The name of the algorithm is specified in algorithm, e.g. <em>"twofish"</em> or is
one of the <strong><code>MCRYPT_ciphername</code></strong> constants. The module is closed by calling
<span class="function"><a href="function.mcrypt-module-close.html" class="function">mcrypt_module_close()</a></span>.
</p>
</div>
<div class="refsect1 parameters" id="refsect1-function.mcrypt-module-open-parameters">
<h3 class="title">Parameters</h3>
<p class="para">
<dl>
<dt>
<span class="term"><em><code class="parameter">algorithm</code></em></span>
<dd>
<p class="para">One of the <strong><code>MCRYPT_ciphername</code></strong> constants, or the name of the algorithm as string.</p>
</dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">algorithm_directory</code></em></span>
<dd>
<p class="para">
The <em><code class="parameter">algorithm_directory</code></em> parameter is used to locate
the encryption module. When you supply a directory name, it is used. When
you set it to an empty string (<em>""</em>), the value set by the
<em>mcrypt.algorithms_dir</em> <var class="filename">php.ini</var> directive is used. When
it is not set, the default directory that is used is the one that was compiled
into libmcrypt (usually <var class="filename">/usr/local/lib/libmcrypt</var>).
</p>
</dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">mode</code></em></span>
<dd>
<p class="para">One of the <strong><code>MCRYPT_MODE_modename</code></strong> constants, or one of the following strings: "ecb", "cbc", "cfb", "ofb", "nofb" or "stream".</p>
</dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">mode_directory</code></em></span>
<dd>
<p class="para">
The <em><code class="parameter">mode_directory</code></em> parameter is used to locate
the encryption module. When you supply a directory name, it is used. When
you set it to an empty string (<em>""</em>), the value set by the
<em>mcrypt.modes_dir</em> <var class="filename">php.ini</var> directive is used. When
it is not set, the default directory that is used is the one that was compiled-in
into libmcrypt (usually <var class="filename">/usr/local/lib/libmcrypt</var>).
</p>
</dd>
</dt>
</dl>
</p>
</div>
<div class="refsect1 returnvalues" id="refsect1-function.mcrypt-module-open-returnvalues">
<h3 class="title">Return Values</h3>
<p class="para">
Normally it returns an encryption descriptor, or <strong><code>FALSE</code></strong> on error.
</p>
</div>
<div class="refsect1 examples" id="refsect1-function.mcrypt-module-open-examples">
<h3 class="title">Examples</h3>
<p class="para">
<div class="example" id="example-850">
<p><strong>Example #1 <span class="function"><strong>mcrypt_module_open()</strong></span> Examples</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /> $td </span><span style="color: #007700">= </span><span style="color: #0000BB">mcrypt_module_open</span><span style="color: #007700">(</span><span style="color: #0000BB">MCRYPT_DES</span><span style="color: #007700">, </span><span style="color: #DD0000">''</span><span style="color: #007700">,<br /> </span><span style="color: #0000BB">MCRYPT_MODE_ECB</span><span style="color: #007700">, </span><span style="color: #DD0000">'/usr/lib/mcrypt-modes'</span><span style="color: #007700">);<br /><br /> </span><span style="color: #0000BB">$td </span><span style="color: #007700">= </span><span style="color: #0000BB">mcrypt_module_open</span><span style="color: #007700">(</span><span style="color: #DD0000">'rijndael-256'</span><span style="color: #007700">, </span><span style="color: #DD0000">''</span><span style="color: #007700">, </span><span style="color: #DD0000">'ofb'</span><span style="color: #007700">, </span><span style="color: #DD0000">''</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</p>
<p class="para">
The first line in the example above will try to open the <em>DES</em> cipher from
the default directory and the <em>ECB</em> mode from the directory
<var class="filename">/usr/lib/mcrypt-modes</var>. The second example uses
strings as name for the cipher and mode, this only works when the
extension is linked against libmcrypt 2.4.x or 2.5.x.
</p>
<p class="para">
<div class="example" id="example-851">
<p><strong>Example #2 Using <span class="function"><strong>mcrypt_module_open()</strong></span> in encryption</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /> </span><span style="color: #FF8000">/* Open the cipher */<br /> </span><span style="color: #0000BB">$td </span><span style="color: #007700">= </span><span style="color: #0000BB">mcrypt_module_open</span><span style="color: #007700">(</span><span style="color: #DD0000">'rijndael-256'</span><span style="color: #007700">, </span><span style="color: #DD0000">''</span><span style="color: #007700">, </span><span style="color: #DD0000">'ofb'</span><span style="color: #007700">, </span><span style="color: #DD0000">''</span><span style="color: #007700">);<br /><br /> </span><span style="color: #FF8000">/* Create the IV and determine the keysize length, use MCRYPT_RAND<br /> * on Windows instead */<br /> </span><span style="color: #0000BB">$iv </span><span style="color: #007700">= </span><span style="color: #0000BB">mcrypt_create_iv</span><span style="color: #007700">(</span><span style="color: #0000BB">mcrypt_enc_get_iv_size</span><span style="color: #007700">(</span><span style="color: #0000BB">$td</span><span style="color: #007700">), </span><span style="color: #0000BB">MCRYPT_DEV_RANDOM</span><span style="color: #007700">);<br /> </span><span style="color: #0000BB">$ks </span><span style="color: #007700">= </span><span style="color: #0000BB">mcrypt_enc_get_key_size</span><span style="color: #007700">(</span><span style="color: #0000BB">$td</span><span style="color: #007700">);<br /><br /> </span><span style="color: #FF8000">/* Create key */<br /> </span><span style="color: #0000BB">$key </span><span style="color: #007700">= </span><span style="color: #0000BB">substr</span><span style="color: #007700">(</span><span style="color: #0000BB">md5</span><span style="color: #007700">(</span><span style="color: #DD0000">'very secret key'</span><span style="color: #007700">), </span><span style="color: #0000BB">0</span><span style="color: #007700">, </span><span style="color: #0000BB">$ks</span><span style="color: #007700">);<br /><br /> </span><span style="color: #FF8000">/* Intialize encryption */<br /> </span><span style="color: #0000BB">mcrypt_generic_init</span><span style="color: #007700">(</span><span style="color: #0000BB">$td</span><span style="color: #007700">, </span><span style="color: #0000BB">$key</span><span style="color: #007700">, </span><span style="color: #0000BB">$iv</span><span style="color: #007700">);<br /><br /> </span><span style="color: #FF8000">/* Encrypt data */<br /> </span><span style="color: #0000BB">$encrypted </span><span style="color: #007700">= </span><span style="color: #0000BB">mcrypt_generic</span><span style="color: #007700">(</span><span style="color: #0000BB">$td</span><span style="color: #007700">, </span><span style="color: #DD0000">'This is very important data'</span><span style="color: #007700">);<br /><br /> </span><span style="color: #FF8000">/* Terminate encryption handler */<br /> </span><span style="color: #0000BB">mcrypt_generic_deinit</span><span style="color: #007700">(</span><span style="color: #0000BB">$td</span><span style="color: #007700">);<br /><br /> </span><span style="color: #FF8000">/* Initialize encryption module for decryption */<br /> </span><span style="color: #0000BB">mcrypt_generic_init</span><span style="color: #007700">(</span><span style="color: #0000BB">$td</span><span style="color: #007700">, </span><span style="color: #0000BB">$key</span><span style="color: #007700">, </span><span style="color: #0000BB">$iv</span><span style="color: #007700">);<br /><br /> </span><span style="color: #FF8000">/* Decrypt encrypted string */<br /> </span><span style="color: #0000BB">$decrypted </span><span style="color: #007700">= </span><span style="color: #0000BB">mdecrypt_generic</span><span style="color: #007700">(</span><span style="color: #0000BB">$td</span><span style="color: #007700">, </span><span style="color: #0000BB">$encrypted</span><span style="color: #007700">);<br /><br /> </span><span style="color: #FF8000">/* Terminate decryption handle and close module */<br /> </span><span style="color: #0000BB">mcrypt_generic_deinit</span><span style="color: #007700">(</span><span style="color: #0000BB">$td</span><span style="color: #007700">);<br /> </span><span style="color: #0000BB">mcrypt_module_close</span><span style="color: #007700">(</span><span style="color: #0000BB">$td</span><span style="color: #007700">);<br /><br /> </span><span style="color: #FF8000">/* Show string */<br /> </span><span style="color: #007700">echo </span><span style="color: #0000BB">trim</span><span style="color: #007700">(</span><span style="color: #0000BB">$decrypted</span><span style="color: #007700">) . </span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</p>
</div>
<div class="refsect1 seealso" id="refsect1-function.mcrypt-module-open-seealso">
<h3 class="title">See Also</h3>
<p class="para">
<ul class="simplelist">
<li class="member"> <span class="function"><a href="function.mcrypt-module-close.html" class="function" rel="rdfs-seeAlso">mcrypt_module_close()</a> - Closes the mcrypt module</span></li>
<li class="member"> <span class="function"><a href="function.mcrypt-generic.html" class="function" rel="rdfs-seeAlso">mcrypt_generic()</a> - This function encrypts data</span></li>
<li class="member"> <span class="function"><a href="function.mdecrypt-generic.html" class="function" rel="rdfs-seeAlso">mdecrypt_generic()</a> - Decrypts data</span></li>
<li class="member"> <span class="function"><a href="function.mcrypt-generic-init.html" class="function" rel="rdfs-seeAlso">mcrypt_generic_init()</a> - This function initializes all buffers needed for encryption</span></li>
<li class="member"> <span class="function"><a href="function.mcrypt-generic-deinit.html" class="function" rel="rdfs-seeAlso">mcrypt_generic_deinit()</a> - This function deinitializes an encryption module</span></li>
</ul>
</p>
</div>
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