PHP: Generar claves aleatóriamente

function generatePassword($length = 10) {
            $characters = '0123456789';
            $characters .= 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
            $charactersLength = strlen($characters)-1;
            $password = '';
  
            for ($i = 0; $i < $length; $i++) {
                $password .= $characters[mt_rand(0, $charactersLength)];
            }     
            return $password;
    }