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<refentry xml:id="function.mcrypt-get-key-size" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>mcrypt_get_key_size</refname>
  <refpurpose>Gets the key size of the specified cipher</refpurpose>
 </refnamediv>
 
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>int</type><methodname>mcrypt_get_key_size</methodname>
   <methodparam><type>int</type><parameter>cipher</parameter></methodparam>
  </methodsynopsis>
  <methodsynopsis>
   <type>int</type><methodname>mcrypt_get_key_size</methodname>
   <methodparam><type>string</type><parameter>cipher</parameter></methodparam>
   <methodparam><type>string</type><parameter>mode</parameter></methodparam>
  </methodsynopsis>
  <para>
   The first prototype is when linked against libmcrypt 2.2.x, the
   second when linked against libmcrypt 2.4.x or 2.5.x.
  </para>
  <para>
   <function>mcrypt_get_key_size</function> is used to get the size
   of a key of the specified <parameter>cipher</parameter> (in
   combination with an encryption mode).
  </para>
  <para>
   It is more useful to use the <function>mcrypt_enc_get_key_size</function>
   function as this uses the resource returned by <function>mcrypt_module_open</function>.
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>cipher</parameter></term>
     <listitem>
      &mcrypt.parameter.cipher;
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>mode</parameter></term>
     <listitem>
      &mcrypt.parameter.mode;
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   Returns the maximum supported key size of the algorithm in bytes
   &return.falseforfailure;.
  </para>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>mcrypt_get_key_size</function> Example</title>
    <programlisting role="php">
<![CDATA[
<?php
    echo mcrypt_get_key_size('tripledes', 'ecb');
?>
]]>
    </programlisting>
    <para>
     The example above shows how to use this function when
     linked against libmcrypt 2.4.x or 2.5.x.
    </para>
    &example.outputs;
    <screen>
<![CDATA[
24
]]>
    </screen>
   </example>   
  </para>
 </refsect1>
 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>mcrypt_get_block_size</function></member>
    <member><function>mcrypt_enc_get_key_size</function></member>
    <member><function>mcrypt_encrypt</function></member>
   </simplelist>
  </para>
 </refsect1>

</refentry>

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