Replacement getkirby/toolkit/lib/password.php using PHP 5.5 password_* functions and paragonie/password_lock inspired SHA512 pre-hashing to support passwords with more than 72 characters.

password.php

<?php

class Password {
  static public function hash($plaintext) {
    return password_hash(base64_encode(hash('sha512', $plaintext, true)), PASSWORD_DEFAULT);
  }
  static public function isHash($hash) {
    $info = password_get_info($hash);
    return $info['algo'] !== 0;
  }
  static public function check($plaintext, $hash) {
    return password_verify(base64_encode(hash('sha512', $plaintext, true)), $hash);
  }
}