Boheung Chung's research while affiliated with Electronics and Telecommunications Research Institute and other places

When implementing a quantum circuit for a desired reversible function, an attempt is made to design an accurate quantum circuit. Then, the quantum circuit is optimized based on a specific cost function, such as design cost, width (the number of qubits), depth, etc. In particular, if an in-place subcircuit itself can be optimized while maintaining its in-place property, it will be a very useful way to increase efficiency without changing the initial architecture of the entire quantum circuit. Furthermore, since its (clean) work qubits can easily be utilized in subsequent subroutines of the quantum circuit, it has an additional important advantage in terms of width. In this paper, for the first time to the best of our knowledge, we present a global Toffoli-depth reduction methodology for an in-place version reversible circuit in the case that the given input circuit is optimized with Toffoli-count. We mainly introduce a process to optimize the χ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\chi $$\end{document} internal function block in SHA3-256 to explain our Toffoli-depth reduction approach preserving the in-place property, and hence, well-balanced five χ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\chi $$\end{document} quantum circuits are induced in terms of its width and T-depth. And then, we apply these five χ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\chi $$\end{document} circuits to design the entire SHA3-256 cryptosystem. One of the proposed SHA3-256 quantum circuits has a width of 1600 and a T-depth of 264, and this shows a result of 50% and 38.9% reduction compared to the previous circuit in terms of width and T-depth, respectively. Other versions of our SHA3-256 circuits just required 10–33 qubits per one T-depth compared to the previous results which require over 1800 qubits per T-depth, and so this means that our SHA3-256 circuits are well-balanced. Finally, we constructed Grover’s algorithm circuit using each version that realized SHA3-256. When output circuits for the presented method were used, quantum volume values of Grover’s algorithm circuits became 33 and 50%\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\%$$\end{document} of the value when the input circuit was used.

We propose a method for efficient mixed polarity multiple controlled Toffoli (MPMCT) gate decomposition from the perspective of a cost metric related to Toffoli gates, namely Toffoli-depth. When using the technique presented in a previous study, there is a range in which Toffoli-depth (consequently T-depth) of the implemented circuit increases proportionally as the number of provided (clean) work qubits increases. In other words, using the previous technique may result in more inefficient MPMCT gates even though the number of helpful work qubits has increased. In this work, a technique is devised to provide sufficient help from clean work qubits at the central part of the implemented circuit as many as possible, thereby addressing the issues with the previous technique. Meanwhile, one of the representative algorithms that use MPMCT gates is Grover’s algorithm. We show the implementation results for MPMCT gates according to the number of work qubits, using Grover’s algorithm as an example. It is experimentally demonstrated that T-depth decreases much more quickly when using our method than the previous method.

Connected and autonomous vehicles (CAVs) are an innovative form of traditional vehicles. Automotive Ethernet replaces the controller area network and FlexRay to support the large throughput required by high-definition applications. As CAVs have numerous functions, they exhibit a large attack surface and an increased vulnerability to attacks. However, no previous studies have focused on intrusion detection in automotive Ethernet-based networks. In this paper, we present an intrusion detection method for detecting audio-video transport protocol (AVTP) stream injection attacks in automotive Ethernet-based networks. To the best of our knowledge, this is the first such method developed for automotive Ethernet. The proposed intrusion detection model is based on feature generation and a convolutional neural network (CNN). To evaluate our intrusion detection system, we built a physical BroadR-Reach-based testbed and captured real AVTP packets. The experimental results show that the model exhibits outstanding performance: the F1-score and recall are greater than 0.9704 and 0.9949, respectively. In terms of the inference time per input and the generation intervals of AVTP traffic, our CNN model can readily be employed for real-time detection.

Connected and autonomous vehicles (CAVs) are an innovative form of traditional vehicles. Automotive Ethernet replaces the controller area network and FlexRay to support the large throughput required by high-definition applications. As CAVs have numerous functions, they exhibit a large attack surface and an increased vulnerability to attacks. However, no previous studies have focused on intrusion detection in automotive Ethernet-based networks. In this paper, we present an intrusion detection method for detecting audio-video transport protocol (AVTP) stream injection attacks in automotive Ethernet-based networks. To the best of our knowledge, this is the first such method developed for automotive Ethernet. The proposed intrusion detection model is based on feature generation and a convolutional neural network (CNN). To evaluate our intrusion detection system, we built a physical BroadR-Reach-based testbed and captured real AVTP packets. The experimental results show that the model exhibits outstanding performance: the F1-score and recall are greater than 0.9704 and 0.9949, respectively. In terms of the inference time per input and the generation intervals of AVTP traffic, our CNN model can readily be employed for real-time detection.

With the development of vehicular ad-hoc networks (VANETs) and Internet of vehicles (IoVs), a large amount of useful information is generated for vehicle drivers and traffic management systems. The amount of vehicle and traffic information is as large as the number of vehicles and it is enormous when compared to vehicle calculation and storage performance. To resolve this problem, VANET uses a combined cloud computing technology, called vehicular cloud computing (VCC), which controls vehicle-related data, and helps vehicle drivers directly or indirectly. However, VANETs remain vulnerable to attacks such as tracking, masquerade and man-in-the-middle attacks because VANETs communicate via open networks. To overcome these issues, many researchers have proposed secure authentication protocols for message confirmation with vehicular cloud computing. However, many researchers have pointed out that some proposed protocols use ideal tamper-proof devices (TPDs). They demonstrated that realistic TPDs cannot prevent adversaries attack. Limbasiya et al. presented a message confirmation scheme for vehicular cloud computing using a realistic TPD in order to prevent these problems. However, their proposed scheme still has security weaknesses over a TPD and does not guarantee mutual authentication. This paper proposes a secure key agreement and authentication protocol to address the security weaknesses inherent in the protocol of Limbasiya et al. The suggested protocol withstands malicious attacks and ensures secure mutual authentication for privacy-preserving. We prove that the proposed protocol can provide session key security using Real-Or-Random (ROR) model. We also employed Automated Validation of Internet Security Protocols and Applications (AVISPA) simulation tool to show that the proposed protocol is able to defeat replay and man-in-the-middle attacks. Furthermore, we established that the proposed protocol can resist other malicious attacks by conducting the informal security analysis. We proved that our proposed protocol is lightweight and suitable for VCC environments.

With the developments in communication and mobile technologies, mobile users can access roaming services by utilizing a mobile device at any time and any place in the global mobility networks. However, these require several security requirements, such as authentication and anonymity, because the information is transmitted over an open channel. Thus, secure and efficient authentication protocols are essential to provide secure roaming services for legitimate users. In 2018, Madhusudhan et al. presented a secure authentication protocol for global mobile networks. However, we demonstrated that their protocol could not prevent potential attacks, including masquerade, session key disclosure, and replay attacks. Thus, we proposed a secure and efficient three-factor authentication protocol to overcome the security weaknesses of Madhusudhan et al.’s scheme. The proposed scheme was demonstrated to prevent various attacks and provided a secure mutual authentication by utilizing biometrics and secret parameters. We evaluated the security of the proposed protocol using informal security analysis and formal security analysis, such as the real-or-random (ROR) model and Burrows–Abadi–Needham (BAN) logic. In addition, we showed that our scheme withstands man-in-the-middle (MITM) and replay attacks utilizing formal security validation automated validation of internet security protocols and applications (AVISPA) simulation. Finally, we compared the performance of our protocol with existing schemes. Consequently, our scheme ensured better security and efficiency features than existing schemes and can be suitable for resource-constrained mobile environments.

With the development in wireless communication and low-power device, users can receive various useful services such as electric vehicle (EV) charging, smart building, and smart home services at anytime and anywhere in smart grid (SG) environments. The SG devices send demand of electricity to the remote control center and utility center (UC) to use energy services, and UCs handle it for distributing electricity efficiently. However, in SG environments, the transmitted messages are vulnerable to various attacks because information related to electricity is transmitted over an insecure channel. Thus, secure authentication and key agreement are essential to provide secure energy services for legitimate users. In 2019, Kumar et al. presented a secure authentication protocol for demand response management in the SG system. However, we demonstrate that their protocol is insecure against masquerade, the SG device stolen, and session key disclosure attacks and does not ensure secure mutual authentication. Thus, we propose a privacy-preserving lightweight authentication protocol for demand response management in the SG environments to address the security shortcomings of Kumar et al.’s protocol. The proposed protocol withstands various attacks and ensures secure mutual authentication and anonymity. We also evaluated the security features of the proposed scheme using informal security analysis and proved the session key security of proposed scheme using the ROR model. Furthermore, we showed that the proposed protocol achieves secure mutual authentication between the SG devices and the UC using Burrows–Abadi–Needham (BAN) logic analysis. We also demonstrated that our authentication protocol prevents man-in-the-middle and replay attacks utilizing AVISPA simulation tool and compared the performance analysis with other existing protocols. Therefore, the proposed scheme provides superior safety and efficiency other than existing related protocols and can be suitable for practical SG environments.