<?xml version="1.0" encoding="utf-8"?>
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<refentry xml:id="function.password-needs-rehash" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
 <refnamediv>
  <refname>password_needs_rehash</refname>
  <refpurpose>Checks if the given hash matches the given options</refpurpose>
 </refnamediv>

 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>bool</type><methodname>password_needs_rehash</methodname>
   <methodparam><type>string</type><parameter>hash</parameter></methodparam>
   <methodparam><type class="union"><type>string</type><type>int</type><type>null</type></type><parameter>algo</parameter></methodparam>
   <methodparam choice="opt"><type>array</type><parameter>options</parameter><initializer>[]</initializer></methodparam>
  </methodsynopsis>
  <para>
   This function checks to see if the supplied hash implements the algorithm
   and options provided. If not, it is assumed that the hash needs to be
   rehashed.
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <variablelist>
   <varlistentry>
    <term><parameter>hash</parameter></term>
    <listitem>
     <para>
      &password.parameter.hash;
     </para>
    </listitem>
   </varlistentry>
   <varlistentry>
    <term><parameter>algo</parameter></term>
    <listitem>
     <para>
      &password.parameter.algo;
     </para>
    </listitem>
   </varlistentry>
   <varlistentry>
    <term><parameter>options</parameter></term>
    <listitem>
     <para>
      &password.parameter.options;
     </para>
    </listitem>
   </varlistentry>
  </variablelist>
 </refsect1>
 
 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   Returns &true; if the hash should be rehashed to match the given
   <parameter>algo</parameter> and <parameter>options</parameter>, or &false;
   otherwise.
  </para>
 </refsect1>

 <refsect1 role="changelog">
  &reftitle.changelog;
  <para>
   <informaltable>
    <tgroup cols="2">
     <thead>
      <row>
       <entry>&Version;</entry>
       <entry>&Description;</entry>
      </row>
     </thead>
     <tbody>
      <row>
       <entry>7.4.0</entry>
       <entry>
        The <parameter>algo</parameter> parameter expects a &string; now, but still accepts
        &integer;s for backward compatibility.
       </entry>
      </row>
     </tbody>
    </tgroup>
   </informaltable>
  </para>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title>Usage of <function>password_needs_rehash</function></title>
    <programlisting role="php">
<![CDATA[
<?php

$password = 'rasmuslerdorf';
$hash = '$2y$10$YCFsG6elYca568hBi2pZ0.3LDL5wjgxct1N8w/oLR/jfHsiQwCqTS';

$algorithm = PASSWORD_BCRYPT;
// bcrypt's cost parameter can change over time as hardware improves
$options = ['cost' => 12];

// Verify stored hash against plain-text password
if (password_verify($password, $hash)) {
    // Check if either the algorithm or the options have changed
    if (password_needs_rehash($hash, $algorithm, $options)) {
        // If so, create a new hash, and replace the old one
        $newHash = password_hash($password, $algorithm, $options);

        // Update the user record with the $newHash
    }

    // Perform the login.
}
?>
]]>
    </programlisting>
   </example>
  </para> 
 </refsect1>

</refentry>

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