A more secure authentication scheme for telecare medicine information systems.

It is important to guarantee the privacy and the security of the users in the telecare medicine information system. Recently, Wu et al.'s proposed an authentication scheme for mobile devices in telecare medicine information system. They added the pre-computing idea within the communication process to avoid the time-consuming exponential computations. They also claimed their scheme can withstand various attacks. We will show that their scheme suffers from the impersonation attack to the insider's attack. In order to overcome the weaknesses, we propose an improved scheme to eliminate the weakness. Our scheme is not only more secure than Wu et al.'s scheme, but also has better performance. Then our scheme is more efficient and appropriate to collocating with low power mobile devices for the telecare medicine information system.