Authenticated key agreement schemes for multi-server architecture enable a user to register with one registration server and access multiple remote application servers rapidly and conveniently to receive services from them. Several efficient authenticated key agreement schemes have recently been developed for multi-server architecture. However, most of them face many security threats and cannot resist potential attacks. This investigation considers the limitations of previous schemes and proposes a novel efficient and secure multi-server authenticated key agreement scheme that uses Physically Unclonable Functions (PUFs); it is based on a hardware circuit and provides randomness, uniqueness and unclonability to support the lightweight authentication of devices. The proposed scheme protects user privacy and is formally proved to satisfy mutual authentication and session key agreement. This scheme solves problems that were left unsolved in previous works, provides more security, and has a low computational cost.

Group authenticated key agreements (GAKAs) for an Internet of Medical Things (IoMT) enable medical sensor devices to authenticate each other and agree upon a common session key. These medical sensor devices can then establish a secure channel using this session key and exchange information securely. Owing to hardware limitations, sensors do not have sufficient computing power, energy, and storage resources to implement burdensome protocols. Moreover, sensors are easily damaged, causing the number of members of the group to change. Therefore, a group key agreement (GKA) protocol is required to consider dynamic groups and reduce the computational cost of an IoMT. The physical unclonable function (PUF) uses the uniqueness and randomness of its circuit to perform calculations. It has message fingerprints so that the user is not necessary to store a private key. The PUF is less computationally burdensome than the more common modular exponentiation and can be applied in an IoMT environment with limited resources. This article develops lightweight anonymous dynamic GAKA (DGAKA) that uses the PUF to solve the problems of data storage, transmission security, and computing efficiency that are faced by the IoMT. The proposed protocol has higher security and efficiency in computation and storage than those previously developed.

Telemonitoring using the Internet of Medical Things (IoMT) enables the seamless communication of physical signs from patients who do not visit healthcare providers. It, therefore, improves the efficiency of healthcare services and patient comfort the quality of life of patients. While providing many benefits, it is associated with challenges concerning energy consumption, privacy, and security. This work addresses those challenges by presenting a new group-oriented time-bound-authenticated key agreement scheme using extended chaotic maps. It provides details on the importance and contribution of this work, investigates the scheme of Chien, and elucidates its weaknesses. The security of the proposed scheme is analyzed formally using the Burrows-Abadi-Needham logic and informally through informal discussions about security features, possible attacks, and countermeasures. Results of a simulation demonstrate that the proposed scheme has more security functions and is more computationally efficient than other related schemes.

ABSTRACT User authentication procedures are essential for global mobility networks and enable a mobile user to communicate securely with other users. Chang et al. recently presented an efficient authentication scheme with user anonymity in roaming environments. The authentication scheme of Chang et al. used low‐cost functions and was most suitable for battery‐powered mobile environments. However, Youn et al. pointed out that their authentication scheme cannot ensure user anonymity and resist known session key and side channel attacks. This study will demonstrate that the scheme of Chang et al. cannot resist impersonation attacks and violates session key security. In addition, this study present a secure and efficient authentication scheme based on the scheme of Chang et al. The proposed scheme not only avoids the weaknesses of the authentication scheme of Chang et al. but also ensures data unlinkability and users untrackabilty. Copyright © 2013 John Wiley & Sons, Ltd.

ABSTRACT Three‐party encrypted key exchange (3PEKE) enables two communicating parties to securely exchange confidential and authenticated information over an insecure network via a trusted server. This investigation presents a novel efficient and secure 3PEKE protocol using a super‐poly‐to‐one trapdoor function. The proposed protocol employs the Diffie–Hellman key exchange and adopts the technique that the clients can publicly exchange the factors for generating the session key without the help of the server to reduce the numbers of transmissions. A round‐efficient version of the proposed 3PEKE protocol is also described. Compared with related approaches, the proposed protocol not only retains security requirements and possesses lower computational cost but also has fewer transmissions and realizes the lower bounds of communications. Copyright © 2013 John Wiley & Sons, Ltd.

Lee and Yeh recently presented a delegation-based authentication protocol for portable communication systems (PCSs), which is claimed to provide non-repudiation in on-line authentication. This investigation indicates that their protocol has a weakness in that a malicious visited location register can forge the authentication messages in off-line authentication processes, preventing mobile users from obtaining non-repudiation in such processes. This study also presents an enhanced protocol, which not only has the same security properties as the original protocol but also avoids the weakness in the original scheme and reduces the computational cost.