This pream ciphers with paper makes three contributions to the research of low-resource stream ciphers with authentication. we analyze dragon-MAC and tiny dragon, both of which are based on the eSTREAM fianlist dragon. we show that they have security weaknesses that might lead to message forgeries. we derive more accurate results for linear cryptanalysis of tini dragon, allowing us to propose tiny dragon II. this variant requires less than a kilobyte of memory, while offering better security than the larger tiny dragon.