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<refentry xml:id="function.mcrypt-encrypt" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>mcrypt_encrypt</refname>
  <refpurpose>Encrypts plaintext with given parameters</refpurpose>
 </refnamediv>
 
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>string</type><methodname>mcrypt_encrypt</methodname>
   <methodparam><type>string</type><parameter>cipher</parameter></methodparam>
   <methodparam><type>string</type><parameter>key</parameter></methodparam>
   <methodparam><type>string</type><parameter>data</parameter></methodparam>
   <methodparam><type>string</type><parameter>mode</parameter></methodparam>
   <methodparam choice="opt"><type>string</type><parameter>iv</parameter></methodparam>
  </methodsynopsis>
  <para>
   Encrypts the data and returns it.
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>cipher</parameter></term>
     <listitem>
      <para>
       One of the <literal>MCRYPT_ciphername</literal>
       constants of the name of the algorithm as string.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>key</parameter></term>
     <listitem>
      <para>
       The key with which the data will be encrypted. If it's smaller that
       the required keysize, it is padded with '<literal>\0</literal>'. It is
       better not to use ASCII strings for keys.
      </para>
      <para>
       It is recommended to use the mhash functions to create a key from a
       string.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>data</parameter></term>
     <listitem>
      <para>
       The data that will be encrypted with the given cipher and mode. If the
       size of the data is not n * blocksize, the data will be padded with
       '<literal>\0</literal>'.
      </para>
      <para>
       The returned crypttext can be larger that the size of the data that is
       given by <parameter>data</parameter>.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>mode</parameter></term>
     <listitem>
      <para>
       One of the <literal>MCRYPT_MODE_modename</literal>
       constants of one of "ecb", "cbc", "cfb", "ofb", "nofb" or
       "stream".
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>iv</parameter></term>
     <listitem>
      <para>
       Used for the initialisation in CBC, CFB, OFB modes, and in some
       algorithms in STREAM mode. If you do not supply an IV, while it is
       needed for an algorithm, the function issues a warning and uses an
       IV with all bytes set to '<literal>\0</literal>'.
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   Returns the encrypted data, as a string.
  </para>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>mcrypt_encrypt</function> Example</title>
    <programlisting role="php">
<![CDATA[
<?php
    $iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_ECB);
    $iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);
    $key = "This is a very secret key";
    $text = "Meet me at 11 o'clock behind the monument.";
    echo strlen($text) . "\n";

    $crypttext = mcrypt_encrypt(MCRYPT_RIJNDAEL_256, $key, $text, MCRYPT_MODE_ECB, $iv);
    echo strlen($crypttext) . "\n";
?>
]]>
    </programlisting>
    &example.outputs;
    <screen>
<![CDATA[
42
64
]]>
    </screen>
   </example>
  </para>
  <para>
   See also <function>mcrypt_module_open</function> for a more advanced API
   and an example.
  </para>
 </refsect1>
</refentry>

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