The conventional electricity infrastructure relies on the usage of fossil fuels, which harms the environment greatly. A smart grid is an infrastructure that enables the integration of renewable resources with the distribution system, as well as the potential of establishing a two-way flow of energy and data between network management and subscribers in order to optimize energy use. However, this data flow may be misused by attackers to disrupt security and causes power network imbalances.Therefore, it is necessary to exploit different security protocols to exchange data in this platform. One of these security protocols is the authenticated key agreement protocol, which allows the parties to authenticate each other and share a key to encrypt data. Recently Zhang et al. proposed a lightweight key authentication protocol based on hash functions. In this paper, we examine their protocol and show that vulnerable to denial of service (DOS) attack and also is not optimized to implement on smart grid. Then we present a lightweight and secure authentication protocol based on hash functions.

In medical fields, a wearable body area sensors network is a network of sensors placed inside human bodies or on their skin. These multi-functional sensors provide all patients and medical personnel with optimized and comfortable services. The patient’s physiological information transferred in this network is very sensitive and confidential; Therefore, transmitting through an insecure channel requires high anonymity, un-traceability, and privacy-preserving of personal data. Furthermore, the wearable body area network is a small part of the Internet of Things (IoT) community, and as the devices are resource-constraint, lightweight protocols are needed to guarantee the information’s authenticity, confidentiality, and integrity. Hence, a large number of schemes were proposed by different researchers to improve the reliability of the protocols. Recently Ankur Gupta and his colleagues proposed a lightweight mutual authentication and key agreement protocol and proved its security against well-known attacks. In this paper, we will demonstrate that their proposed protocol is vulnerable to the sensor node impersonation attack and does not provide the necessary security for communicating data; Then, we will offer a new solution to overcome this problem.