• The KIPS Transactions:PartC
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• v.16C no.5
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• pp.589-596
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• 2009

Until now, some protocols have been presented to provide vehicle's anonymity and unlinkability in VANET by means of issuing multiple anonymous certificates to each vehicle from the trust authority, or shot-time anonymous certificate to a vehicle after mutual authentication between a Roadside Unit (RSU) and the vehicle. However, these protocols have high overheads of the trust authority, RSUs and vehicles for generating anonymous certificate. In this paper, we propose an efficient anonymous authentication protocol, in which RSUs can issue multiple shot-time anonymous certificates to a vehicle to alleviate system overheads for mutual authentication between vehicles and RSUs. Several simulations are conducted to verify the efficiency of the proposed protocol in terms of RSU valid serve ratio and vehicle's computational costs. Moreover, the proposed protocol provides unlinkability and traceability when multiple RSUs are compromised, whereas previous protocols do not provide unlinkability and traceability.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.4
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• pp.78-85
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• 2011

In vehicle ad-hoc network (VANET) environments, traffic related information such as accident information, emergency information and real time traffic condition have to be delivered to on-board-unit (OBU) or/and road-side-equipment (RSE) for preventing traffic accidents in advance. In this paper, we introduce a Multi-Channel MAC (MCM) since the existing single channel operation may cause packet transmission delay and unexpected communication failure. To offer a seamless safety message transmission during the various services, it is necessary to manage the MAC scheduler in wireless access in vehicular environments (WAVE) systems. The MCM consists of MAC softwares and MAC hardwares where the former and the later ones are implemented with real time operation system based C language and FPGA module with VHDL language, respectively. The performance and QoS are verified by practical measurements and compared with the scheme using single channel operation.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.20 no.4
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• pp.75-87
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• 2010

Secure communication has been one of the main challenges in vehicular ad hoc networks(VANET) since broadcast messages from nearby vehicles contain life-critical information for drivers and passengers. So far various secure communication schemes have been proposed to secure the communication in VANET, and they satisfy most security requirements. However most of them need to put trust on roadside units(RSUs), which are usually deployed in unattended area and vulnerable to compromise. In this paper, we propose a secure communication scheme, which does not need to put trust on RSUs. And we adopt a grouping technique to averagely divide the huge burden in the server without jeopardizing the anonymity of users. Moreover we design a complete set of protocols to satisfy common security requirements with a relatively lower hardware requirement. At last, we evaluate the scheme with respect to security requirements, communication overhead, storage overhead and network performance.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.19 no.4
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• pp.105-114
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• 2009

Messages exchanged among vehicles must be authenticated in order to provide collision avoidance and cooperative driving services in VANET. However, digitally signing the messages can violate the privacy of users. Therefore, we require authentication systems that can provide conditional anonymity. Recently, Zhang et al. proposed conditionally anonymous authentication system for VANET using tamper-resistant hardware. In their system, vehicles can generate identity-based public keys by themselves and use them to sign messages. Moreover, they use batch verification to effectively verify signed messages. In this paper, we provide amelioration to Zhang et al.'s system in the following respects. First, we use a more efficient probabilistic signature scheme. Second, unlike Zhang et al., we use a security proven batch verification scheme. We also provide effective solutions for key revocation and anonymity revocation problems.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.4
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• pp.31-40
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• 2016

In vehicular ad-hoc networks (VANETs), vehicles sense information on emergency incidents (e.g., accidents, unexpected road conditions, etc.) and propagate this information to following vehicles and a server to share the information. However, this process of emergency message propagation is based on multiple broadcast messages and can lead to broadcast storms. To address this issue, in this work, we use a novel approach to detect the vehicles that are farthest away but within communication range of the transmitting vehicle. Specifically, we discuss a signal-to-noise ratio (SNR)-based linear back-off (SLB) scheme where vehicles implicitly detect their relative locations to the transmitter with respect to the SNR of the received packets. Once the relative locations are detected, nodes that are farther away will set a relatively shorter back-off to prioritize its forwarding process so that other vehicles can suppress their transmissions based on packet overhearing. We evaluate SLB using a realistic simulation environment which consists of a NS-3 VANET simulation environment, a software-based WiFi-IP gateway, and an ITS server operating on a separate machine. Comparisons with other broadcasting-based schemes indicate that SLB successfully propagates emergency messages with latencies and hop counts that is close to the experimental optimal while reducing the number of transmissions by as much as 1/20.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.1
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• pp.96-107
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• 2015

VANET technologies provide real-time traffic information for mitigating traffic jam and preventing traffic accidents, as well as in-vehicle infotainment service through Telematics/Intelligent Transportation System (ITS). Due to the rapid increasement of various requirements, the vehicle communication with a limited resource and the fixed frame architecture of the conventional techniques is limited to provide an efficient communication service. Therefore, a new flexible operation depending on the surrounding situation information is required that needs an adaptive design of the network architecture and protocol for efficiently predicting, distributing and sharing the context-aware information. In this paper, Vehicle-to-Infrastructure (V2I) based on communication between vehicle and a Road Side Units (RSU) and Vehicle-to-Vehicle (V2V) based on communication between vehicles are effectively combined in a new MAC architecture and V2I and V2V vehicles collaborate in management. As a result, many vehicles and RSU can use more efficiently the resource and send data rapidly. The simulation results show that the proposed method can achieve high resource utilization in accordance. Also we can find out the optimal transmission relay time and 2nd relay vehicle selection probability value to spread out V2V/V2I collaborative schedule message rapidly.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.5
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• pp.795-807
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• 2014

Vehicular Ad hoc Network (VANET) has gone through a rich amount of research and currently is making its way towards the deployment. However, surprisingly it evolved to rather more applications and services-rich breed referred to as VANET-based clouds due to the advancements in the automobile and communication technologies. Security and privacy have always been the challenges for the think tanks to deploy this technology on mass scale. It is even worse that some security issues are orthogonally related to each other such as privacy, revocation and route tracing. In this paper, we aim at a specific VANET-based clouds framework proposed by Hussain et al. namely VANET using Clouds (VuC) where VANET and cloud infrastructure cooperate with each other in order to provide VANET users (more precisely subscribers) with services. We specifically target the aforementioned conflicted privacy, route tracing, and revocation problem in VANET-based clouds environment. We propose a multiple pseudonymous approach for privacy reasons and leverage the beacons stored in the cloud infrastructure for both route tracing and revocation. In the proposed scheme, revocation authorities after colluding, can trace the path taken by the target node for a specified timespan and can also revoke the identity if needed. Our proposed scheme is secure, conditional privacy preserved, and is computationally less expensive than the previously proposed schemes.