php-passchk is a semi-faithful port of Tyler Akins's passchk.js. The main impetus to write this was to have a way to generate the entropy server side from a password. You can then use this measurement to safely set a password expire date with out needing to trust the value from an HTML form value populated from a client side JS call.
To this end, the class not only returns bits in entropy and length, but also time_to_crack, valid and days.
Finally, it also returns the simple_to_bits value based on simple entropy calculate of entropy = n * lg(c) which is mentioned in DropBox's great post on password strength calculation.
To us this library, include it, instantiate it and call ShowStats():
require_once(passchk.php);
$passStats = new passchk();
$passAry = $passStats->ShowStats('correct horse battery staple');
print_r($passAry);
This code will output:
Array
(
[length] => 28
[time_to_crack] => 86 years
[valid] => 86 years
[days] => 31566
[simple_bits] => 92.28
[bits] => 108.64
)
This code is released under the GPLv3 license.
If you see something wrong, please open an issue. If you see something wrong and have time to spare, please open an issue and submit a pull request!