# password_needs_rehash

(PHP 5 >= 5.5.0, PHP 7)

password_needs_rehash — Checks if the given hash matches the given options

### Description

password_needs_rehash ( string `$hash` , mixed `$algo` [, array `$options` ] ) : bool

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.

### Parameters

`hash`

  A hash created by password_hash().

`algo`

  A password algorithm constant denoting the algorithm to use when hashing the password.

`options`

  An associative array containing options. See the password algorithm constants for documentation on the supported options for each algorithm.

### Return Values

Returns `TRUE` if the hash should be rehashed to match the given `algo` and `options`, or `FALSE` otherwise.

### Changelog

Version | Description
--- | ---
7.4.0 | The `algo` parameter expects a string now, but still accepts ints for backward compatibility.

### Examples

Example #1 Usage of password_needs_rehash()

`<?php
$password = 'rasmuslerdorf';
$hash = '$2y$10$YCFsG6elYca568hBi2pZ0.3LDL5wjgxct1N8w/oLR/jfHsiQwCqTS';
// The cost parameter can change over time as hardware improves
$options = array('cost' => 11);
// Verify stored hash against plain-text password
if (password_verify($password, $hash)) {
// Check if a newer hashing algorithm is available
// or the cost has changed
if (password_needs_rehash($hash, PASSWORD_DEFAULT, $options)) {
// If so, create a new hash, and replace the old one
$newHash = password_hash($password, PASSWORD_DEFAULT, $options);
}
// Log user in
}
?>`