On the security of a provably secure, efficient, and flexible authentication scheme for ad hoc wireless sensor networks

In a recent paper, Chang and Le proposed an efficient smart card–based authenticated key exchange protocol (which is referred to as CL scheme) for heterogeneous ad hoc wireless sensor networks. However, we found that the CL scheme is subject to sensor capture attack which breaks the session key security of the CL scheme. An improved protocol is proposed to fix this problem.