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<refentry xmlns="http://docbook.org/ns/docbook" xml:id="function.openssl-random-pseudo-bytes">
 <refnamediv>
  <refname>openssl_random_pseudo_bytes</refname>
  <refpurpose>Generate a pseudo-random string of bytes</refpurpose>
 </refnamediv>
 
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type class="union"><type>string</type><type>false</type></type><methodname>openssl_random_pseudo_bytes</methodname>
   <methodparam><type>int</type><parameter>length</parameter></methodparam>
   <methodparam choice="opt"><type>bool</type><parameter role="reference">crypto_strong</parameter></methodparam>
  </methodsynopsis>
  <para>
   Generates a <type>string</type> of pseudo-random bytes, with the number of bytes
   determined by the <parameter>length</parameter> parameter. 
  </para>
  <para>
   It also indicates if a cryptographically strong algorithm was used to produce the
   pseudo-random bytes, and does this via the optional <parameter>crypto_strong</parameter>
   parameter. It's rare for this to be &false;, but some systems may be broken or old.
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>length</parameter></term>
     <listitem>
      <para>
       The length of the desired string of bytes. Must be a positive integer. PHP will
       try to cast this parameter to a non-null integer to use it. 
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>crypto_strong</parameter></term>
     <listitem>
      <para>
       If passed into the function, this will hold a <type>bool</type> value that determines
       if the algorithm used was "cryptographically strong", e.g., safe for usage with GPG, 
       passwords, etc. &true; if it did, otherwise &false;
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   Returns the generated &string; of bytes on success, &return.falseforfailure;.
  </para>
 </refsect1>
 
 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>openssl_random_pseudo_bytes</function> example</title>
    <programlisting role="php">
<![CDATA[
<?php
for ($i = 1; $i <= 4; $i++) {
    $bytes = openssl_random_pseudo_bytes($i, $cstrong);
    $hex   = bin2hex($bytes);

    echo "Lengths: Bytes: $i and Hex: " . strlen($hex) . PHP_EOL;
    var_dump($hex);
    var_dump($cstrong);
    echo PHP_EOL;
}
?>
]]>
    </programlisting>
    &example.outputs.similar;
    <screen>
<![CDATA[
Lengths: Bytes: 1 and Hex: 2
string(2) "42"
bool(true)

Lengths: Bytes: 2 and Hex: 4
string(4) "dc6e"
bool(true)

Lengths: Bytes: 3 and Hex: 6
string(6) "288591"
bool(true)

Lengths: Bytes: 4 and Hex: 8
string(8) "ab86d144"
bool(true)

]]>
    </screen>
   </example>
  </para>
 </refsect1>

 <refsect1 role="seealso">
  &reftitle.seealso;
  <simplelist>
   <member><function>random_bytes</function></member>
   <member><function>bin2hex</function></member>
   <member><function>crypt</function></member>
   <member><function>mt_rand</function></member>
   <member><function>uniqid</function></member>
  </simplelist>
 </refsect1>
</refentry>

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