The privacy-preserving authentication is considered as the first line of defense against the attacks in addition to preserving the identity privacy of the vehicles in the vehicular ad hoc networks ...(VANETs). However, the existing authentication schemes suffer from drawbacks such as nontransparency of the trusted authorities (TAs), heavy workload to revoke certificates, and high computation overhead to authenticate identities and messages. In this paper, we propose a blockchain-based privacy-preserving authentication (BPPA) scheme for VANETs. In BPPA, all the certificates and transactions are recorded permanently and immutably in the blockchain to make the activities of the semi-TAs transparent and verifiable. However, it remains a challenge how to use such blockchain effectively for authentication in real driving scenarios (e.g., high speed or large amount of messages during congestion). With a novel data structure named the Merkle Patricia tree (MPT), we extend the conventional blockchain structure to provide a distributed authentication scheme without the revocation list. To achieve conditional privacy, we allow a vehicle to use multiple certificates. The linkability between the certificates and real identity is encrypted and stored in the blockchain and can only be revealed in case of disputes. We evaluate the validity and performance of BPPA on the Hyperledger Fabric (HLF) platform for each entity. The experimental results show that the distributed authentication can be processed by individual vehicles within 1 ms, which meets the real-time requirement and is much more efficient, in terms of the processing time and storage requirement, than existing approaches.
The public key infrastructure-based authentication protocol provides basic security services for the vehicular ad hoc networks (VANETs). However, trust and privacy are still open issues due to the ...unique characteristics of VANETs. It is crucial to prevent internal vehicles from broadcasting forged messages while simultaneously preserving the privacy of vehicles against the tracking attacks. In this paper, we propose a blockchain-based anonymous reputation system (BARS) to establish a privacy-preserving trust model for VANETs. The certificate and revocation transparency is implemented efficiently with the proofs of presence and absence based on the extended blockchain technology. The public keys are used as pseudonyms in communications without any information about real identities for conditional anonymity. In order to prevent the distribution of forged messages, a reputation evaluation algorithm is presented relying on both direct historical interactions and indirect opinions about vehicles. A set of experiments is conducted to evaluate BARS in terms of security, validity, and performance, and the results show that BARS is able to establish a trust model with transparency, conditional anonymity, efficiency, and robustness for VANETs.
With its reprogrammability, low design cost, and increasing capacity, field-programmable gate array (FPGA) has become a popular design platform and a target for intellectual property (IP) ...infringement. Currently available IP protection solutions are usually limited to protect single FPGA configurations and require permanent secret key storage in the FPGA. In addition, they cannot provide a commercially popular pay-per-device licensing solution. In this paper, we propose a novel IP protection mechanism to restrict IP's execution only on specific FPGA devices in order to efficiently protect IPs from being cloned, copied, or used with unauthorized integration. This mechanism can also enforce the pay-per-device licensing, which enables the system developers to purchase IPs from the core vendors at the low price based on usage instead of paying the expensive unlimited IP license fees. In our proposed binding-based mechanism, FPGA vendors embed into each enrolled FPGA device with a physical unclonable function (PUF) customized for FPGAs; IP vendors embed augmented finite-state machines (FSM) into the original IPs such that the FSM can be activated by the PUF responses from the FPGA device. We propose protocols to lock and unlock FPGA IPs, demonstrate how PUF can be embedded onto FPGA devices, and analyze the security vulnerabilities of our PUF-FSM binding method. We implement a 128-bit delay-based PUF on 28-nm FPGAs with only 258 RAM-lookup tables and 256 flipflops. The PUF responses are unique and reliable against environment changes. We also synthesize a variety of FSM benchmark circuits. On large benchmarks, the average timing overhead is 0.64% and power overhead in 0.01%.
Hydrogel bioelectronics that can interface biological tissues and flexible electronics is at the core of the growing field of healthcare monitoring, smart drug systems, and wearable and implantable ...devices. Here, a simple strategy is demonstrated to prototype all‐hydrogel bioelectronics with embedded arbitrary conductive networks using tough hydrogels and liquid metal. Due to their excellent stretchability, the resultant all‐hydrogel bioelectronics exhibits stable electrochemical properties at large tensile stretch and various modes of deformation. The potential of fabricated all‐hydrogel bioelectronics is demonstrated as wearable strain sensors, cardiac patches, and near‐field communication (NFC) devices for monitoring various physiological conditions wirelessly. The presented simple platform paves the way of implantable hydrogel electronics for Internet‐of‐Things and tissue–machine interfacing applications.
Stretchable and wireless bioelectronics based on all‐hydrogel microfluidics and liquid metal are fabricated by combining a two‐step crosslinking mechanism and a laser‐engraving method. The perfused liquid metal in hydrogel microchannels form tailor‐designed conductive networks of hydrogel bioelectronics. The applications of all‐hydrogel‐based bioelectronics are demonstrated as wearable and potentially implantable sensors for monitoring physiologically relevant signals wirelessly.
This paper considers a wireless powered communication network (WPCN) with group cooperation, where two communication groups cooperate with each other via wireless power transfer and time sharing to ...fulfill their expected information delivering and achieve "win-win" collaboration. To explore the system performance limits, we formulate optimization problems to maximize the weighted sum-rate (WSR) and minimize the total consumed power. The time assignment, beamforming vector and power allocation are jointly optimized under available power and quality of service requirement constraints of both the groups. For the WSR-maximization, both fixed and flexible power scenarios are investigated. As all problems are non-convex and have no known solution methods, we solve them by using proper variable substitutions and the semi-definite relaxation. We theoretically prove that our proposed solution method guarantees the global optimum for each problem. Numerical results are presented to show the system performance behaviors, which provide some useful insights for future WPCN design. It shows that in such a group cooperation-aware WPCN, optimal time assignment has the greatest effect on the system performance than other factors.
To save resources for Internet of Things (IoT) devices, a proposed approach segments operands and corresponding basic arithmetic operations that can be carried out by approximate function units for ...almost all applications. The approach also increases the security of IoT devices by hiding information for IP watermarking, digital fingerprinting, and lightweight encryption.
Electrocatalytic hydrogen evolution reaction (HER) is a highly potential strategy to massively produce green hydrogen fuels. However, the employment of costly Pt-based electrocatalyst in the cathode ...of electrolyzer greatly hampers the development of hydrogen economy. Ruthenium phosphide catalysts have recently drawn wide attention due to the Pt-like activity but relatively lower cost. Herein, a facile strategy was proposed for the controlled preparation of the ultrasmall RuP
2
nanoparticles on N,P-codoped carbon from common precursors of Ru (II) complex and phytic acid. By taking advantage of simple mixing and pyrolysis, the as-synthesized RuP
2
nanoparticles were uniformly embedded onto the N,P-codoped carbon nanosheet. The composite catalyst shows better activity than Pt/C for alkaline HER and comparable activity for acidic and neutral HER. The superior activity can be ascribed to the ultrasmall-size and efficient RuP
2
together with good mass and charge transfer ability assured by N,P-codoped carbon support. The advantages including low-cost and simple synthesis in this work present an encouraging substitute to replace commercial Pt/C for hydrogen-related practical applications.
Graphic abstract
Sponges, Neofibularia nolitangere, can regenerate spontaneously after being broken down into small pieces, and the regenerated structure maintains the original appearance and function. Synthetic ...materials with such capabilities are highly desired but hardly achieved. Presented here is a sponge‐inspired self‐regenerative powder from a double‐network (DN) tough hydrogel. Hydrogels are regenerated from their powder form, by addition of water, with preservation of the original appearance and mechanical properties. The powder‐hydrogel‐powder cycle can be repeated multiple times with little loss in mechanical properties, analogous to the regeneration of sponges. These DN hydrogels can be conveniently stored and easily shaped upon regeneration. This work may have implications in the development of regenerative materials for coatings and adhesives.
Self‐healing: A sponge‐inspired self‐regenerative double‐network hydrogel that can spontaneously regenerate from its dry powder form has been developed. The powders can be restored to hydrogels having the original appearance and super‐stretchability. They can also be stored for a long time without loss in the regenerative capacity. The powder‐to‐hydrogel transformation provides unprecedented convenience for the purposes of storage as well as the shaping of tough hydrogel‐based materials.
In many industry Internet of Things applications, resources like CPU, memory, and battery power are limited and cannot afford the classic cryptographic security solutions. Silicon physical unclonable ...function (PUF) is a lightweight security primitive that exploits manufacturing variations during the chip fabrication process for key generation and/or device authentication. However, traditional weak PUFs such as ring oscillator (RO) PUF generate chip-unique key for each device, which restricts their application in security protocols where the same key is required to be shared in resource-constrained devices. In this article, in order to address this issue, we propose a PUF-based key sharing method for the first time. The basic idea is to implement one-to-one input-output mapping with lookup table (LUT)-based interstage crossing structures in each level of inverters of RO PUF. Individual customization on configuration bits of interstage crossing structure and different RO selections with challenges bring high flexibility. Therefore, with the flexible configuration of interstage crossing structures and challenges, crossover RO PUF can generate the same shared key for resource-constrained devices, which enables a new application for lightweight key sharing protocols.
Hardware is the foundation of security and trust for any security system. However, recent study has revealed that hardware is subject to a number of security risks. Some of the most severe risks come ...from the VLSI supply chain. Such risks compromise the foundation of any existing security design. In this paper, we present a systematic survey on these security risks and their corresponding mitigation techniques.
Categorization of security threats in VLSI development and supply chain.Evaluation of countermeasure techniques.Categorization of countermeasure techniques.Problem formulation or threat modeling for each countermeasure technique.
PDF
