No abstract

Key agreements that use only password authentication are convenient in communication networks, but these key agreement schemes often fail to resist possible attacks, and therefore provide poor security compared with some other authentication schemes. To increase security, many authentication and key agreement schemes use smartcard authentication in addition to passwords. Thus, two-factor authentication and key agreement schemes using smartcards and passwords are widely adopted in many applications. Vaidya et al. recently presented a two-factor authentication and key agreement scheme for wireless sensor networks (WSNs). Kim et al. observed that the Vaidya et al. scheme fails to resist gateway node bypassing and user impersonation attacks, and then proposed an improved scheme for WSNs. This study analyzes the weaknesses of the two-factor authentication and key agreement scheme of Kim et al., which include vulnerability to impersonation attacks, lost smartcard attacks and man-in-the-middle attacks, violation of session key security, and failure to protect user privacy. An efficient and secure authentication and key agreement scheme for WSNs based on the scheme of Kim et al. is then proposed. The proposed scheme not only solves the weaknesses of previous approaches, but also increases security requirements while maintaining low computational cost.

A group key agreement protocol enables a group of communicating parties over an untrusted, open network to come up with a common secret key. It is designed to achieve secure group communication, which is an important research issue for mobile communication. In 2007, Tseng proposed a new group key agreement protocol to achieve secure group communication for a mobile environment. Its security is based on the decisional Diffie-Hellman assumption. It remedies the security weakness of the protocol of Nam et al. in which participants cannot confirm that their contributions were actually involved in the group key. Unfortunately, Tseng's protocol is a nonauthenticated protocol that cannot ensure the validity of the transmitted messages. In this paper, the authors shall propose a new authenticated group key agreement to remedy it. It is based on bilinear pairings. We shall prove the security of the proposed protocol under the bilinear computational Diffie-Hellman assumption. It is also proven to a contributory group key agreement protocol

The integrated EPR information system supports convenient and rapid e-medicine services. A secure and efficient authentication scheme for the integrated EPR information system provides safeguarding patients' electronic patient records (EPRs) and helps health care workers and medical personnel to rapidly making correct clinical decisions. Recently, Wu et al. proposed an efficient password-based user authentication scheme using smart cards for the integrated EPR information system, and claimed that the proposed scheme could resist various malicious attacks. However, their scheme is still vulnerable to lost smart card and stolen verifier attacks. This investigation discusses these weaknesses and proposes a secure and efficient authentication scheme for the integrated EPR information system as alternative. Compared with related approaches, the proposed scheme not only retains a lower computational cost and does not require verifier tables for storing users' secrets, but also solves the security problems in previous schemes and withstands possible attacks.

A smartcard based password-authenticated key agreement scheme enables a legal user to log in to a remote authentication server and access remote services through public networks using a weak password and a smart card. Lin recently presented an improved chaotic maps-based password-authenticated key agreement scheme that used smartcards to eliminate the weaknesses of the scheme of Guo and Chang, which does not provide strong user anonymity and violates session key security. However, the improved scheme of Lin does not exhibit the freshness property and the validity of messages so it still fails to withstand denial-of-service and privileged-insider attacks. Additionally, a single malicious participant can predetermine the session key such that the improved scheme does not exhibit the contributory property of key agreements. This investigation discusses these weaknesses and proposes an enhanced smartcard-based password-authenticated key agreement scheme that utilizes extended chaotic maps. The session security of this enhanced scheme is based on the extended chaotic map-based Diffie-Hellman problem, and is proven in the real-or-random and the sequence of games models. Moreover, the enhanced scheme ensures the freshness of communicating messages by appending timestamps, and thereby avoids the weaknesses in previous schemes.

The mobile multimedia applications have recently generated much interest in wireless ad hoc networks with supporting the quality-of-service (QoS) communications. The QoS metric considered in this work is the reserved bandwidth, i.e., the time slot reservation. We approach this problem by assuming a common channel shared by all hosts under a TDMA (Time Division Multiple Access) channel model. In this paper, we propose a new TDMA-based QoS multicast routing protocol, namely hexagonal-tree QoS multicast protocol, for a wireless mobile ad hoc network. Existing QoS routing solutions have addressed this problem by assuming a stronger multi-antenna model or a less-strong CDMA-over-TDMA channel model. While more practical and less costly, using a TDMA model needs to face the challenge of radio interference problems. The simpler TDMA model offers the power-saving nature. In this paper, we propose a new multicast tree structure, namely a hexagonaltree, to serve as the QoS multicasting tree, where the MAC sub-layer adopts the TDMA channel model. In this work, both the hidden-terminal and exposed-terminal problems are taken into consideration to possibly exploit the timeslot reuse capability. The hexagonal-based scheme offers a higher success rate for constructing the QoS multicast tree due to the use of the hexagonal-tree. A hexagonal-tree is a tree whose sub-path is a hexagonal-path. A hexagonal-path is a special two-path structure. This greatly improves the success rate by means of multi-path routing. Performance analysis results are discussed to demonstrate the achievement of efficient QoS multicasting.

Secure verified-based three-party authentication scheme for data exchange in telecare medicine information systems enables two users only store their verifiers computed from their actual password in authentication server's database. Then the authentication server can verify the users' verifiers and help them to exchange electronic medical records or electronic health records securely and conveniently. This investigation presents an efficient and secure verified-based three-party authentication scheme for data exchange in telecare medicine information systems. The proposed scheme does not use server's public keys and includes the key confirmation without extra numbers of messages and rounds. Compared to related verified-based approaches, the proposed scheme possesses higher security, has lower computational cost and fewer transmissions, and thus is suitable for the telecare medicine information systems.

A systematic approach to achieve a LRHH (low roughness and high hardness) electroforming process is developed in this study. Because electroformed molds with low roughness and high hardness are required for microlens array fabrication using the LIGA-like process, the invented Ni–Co alloy-pressurized electroforming process is used to fabricate a metallic micro-mold for microlens array molding. The electrolyte parameters such as Co content, current density, brightener content, pH value and temperature will be examined with respect to roughness and hardness. An artificial neural network (ANN) is used to construct a system model that accurately predicts the responses for arbitrary parameter settings. A genetic algorithm (GA) is applied to minimize the surface roughness and improve the micro-mold hardness. The results show that the micro-mold surface roughness and hardness could be significantly improved using the ANN/GA approach. A LRHH electroforming process is carried out using parameter design to improve the surface morphology and increase the service life of the micro-mold during the forming process.