Generating secure passwords in PHP

generatePassword.php

<?php
/**
 * Generates random, secure bytes that will be used for the password.
 *
 * @param int  $nbBytes
 * @param bool $strong
 *
 * @return string
 */
function get_random_bytes( $nbBytes = 32, $strong = true ) {
    $bytes = openssl_random_pseudo_bytes( $nbBytes, $strong );
    if ( false !== $bytes && true === $strong ) {
        return $bytes;
    } else {
        throw new \Exception( 'Unable to generate secure token from OpenSSL.' );
    }
}

/**
 * Generates a random, secure password with the support of openssl.
 *
 * @param int $length
 *
 * @return string
 */
function generate_password( $length = 16 ) {
    return substr( preg_replace( "/[^a-zA-Z0-9]/", "", base64_encode( getRandomBytes( $length + 1 ) ) ), 0, $length );
}