Password Strength Tester

Password Strength Tester

Lately there is a proliferation of password strength testers on an increasing amount of sites. Generally they are annoying and have the same credibility as a 'users on line' script. This simple function goes over the basics or allocating points based on the password content. There are as many variations of this as there are bad hair cuts in #perl. This is provided as an example and returns a number between one and ten based on length, unique characters, numbers and special characters. Feel free to experiment and add more checks, or not.



<?php
/**
 *
 * @simple function to test password strength
 *
 * @param string $password
 *
 * @return int 
 *
 */function testPassword($password)
{
    if ( strlen( $password ) == 0 )
    {
        return 1;
    }

    $strength = 0;

    /*** get the length of the password ***/
    $length = strlen($password);

    /*** check if password is not all lower case ***/
    if(strtolower($password) != $password)
    {
        $strength += 1;
    }
    
    /*** check if password is not all upper case ***/
    if(strtoupper($password) == $password)
    {
        $strength += 1;
    }

    /*** check string length is 8 -15 chars ***/
    if($length >= 8 && $length <= 15)
    {
        $strength += 1;
    }

    /*** check if lenth is 16 - 35 chars ***/
    if($length >= 16 && $length <=35)
    {
        $strength += 2;
    }

    /*** check if length greater than 35 chars ***/
    if($length > 35)
    {
        $strength += 3;
    }
    
    /*** get the numbers in the password ***/
    preg_match_all('/[0-9]/', $password, $numbers);
    $strength += count($numbers[0]);

    /*** check for special chars ***/
    preg_match_all('/[|!@#$%&*\/=?,;.:\-_+~^\\\]/', $password, $specialchars);
    $strength += sizeof($specialchars[0]);

    /*** get the number of unique chars ***/
    $chars = str_split($password);
    $num_unique_chars = sizeof( array_unique($chars) );
    $strength += $num_unique_chars * 2;

    /*** strength is a number 1-10; ***/
    $strength = $strength > 99 ? 99 : $strength;
    $strength = floor($strength / 10 + 1);

    return $strength;
}
/*** example usage ***/$password = 'php_tutorials_and_examples!123';
echo testPassword($password);
?>