PHP MakeSalt

/**
 * makeSalt()
 * generates a random salt up to the requested length
 *
 * @param int $length Length of salt to produce
 */
function makeSalt($length=45) {
  $sequence = array_merge(range(0,9), range('A','Z'), range('a','z'), range('!','.'));
  // remove unsafe characters
  $unsafe = array('"',"'");
  $sequence = array_diff($sequence, $unsafe);
  $length = $length > count($sequence) ? count($sequence) : $length;
  shuffle($sequence);
  $sequence = implode($sequence);
  return substr($sequence, 0, $length);
}