• Journal of the Korea Society of Computer and Information
• /
• v.25 no.7
• /
• pp.93-101
• /
• 2020

Regional CRL(certificate revocation list) in vehicular communications is to partition Full CRL into several small CRLs according to geographic location to keep the size of individual CRLs with smaller. However, since a Regional CRL includes vehicle's revoked certificates within its administrative region, it has to know vehicle' location. For this, how to know vehicle' location effectively corresponding to every region represents a major challenge. This paper proposes a Regional CRL scheme which is envisioned to achieve vehicle's location and to make regional CRLs according to vehicles current location efficiently. The scheme is based on the short-lived pseudonyms defined by WAVE standard. It also acquires issued pseudonyms, vehicle's id and region information whenever a vehicle initiates pseudonyms refill after that, utilizes them to create and distribute the Regional CRL. To keep location privacy-preserving for vehicles, the scheme uses the blockchain technology in the network. The analysis results show that it reduces CRL size and database query time for finding revoked certificates sharply in the vehicle's on-board unit.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.16 no.5
• /
• pp.113-118
• /
• 2006

Pseudonyms must be maintained anonymously even to the organization that issues the pseudonyms, but when some event occurs that policy defines the real identity for the pseudonym must be able to be traced. We propose a private pseudonym retrieval protocol with controlled traceability using m-out-of-n oblivious transfer and cut-and-choose technique.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.12 no.10
• /
• pp.5100-5119
• /
• 2018

Most of existing privacy-preserving multi-authorities attribute-based encryption schemes (PP-MA-ABE) only considers the privacy of the user identity (ID). However, in many occasions information leakage is caused by the disclosing of his/her some sensitive attributes. In this paper, we propose a collusion-resisting ciphertext-policy PP-MA-ABE (CRPP-MACP-ABE) scheme with hiding both user's ID and attributes in the cloud storage system. We present a method to depict anonymous users and introduce a managerial role denoted by IDM for the management of user's anonymous identity certificate ($AID_{Cred}$). The scheme uses $AID_{Cred}$ to realize privacy-preserving of the user, namely, by verifying which attribute authorities (AAs) obtain the blinded public attribute keys, pseudonyms involved in the $AID_{Cred}$ and then distributes corresponding private keys for the user. We use different pseudonyms of the user to resist the collusion attack launched by viciousAAs. In addition, we utilize IDM to cooperate with multiple authorities in producing consistent private key for the user to avoid the collusion attack launched by vicious users. The proposed CRPP-MACP-ABE scheme is proved secure. Some computation and communication costs in our scheme are finished in preparation phase (i.e. user registration). Compared with the existing schemes, our scheme is more efficient.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.13 no.12
• /
• pp.6121-6144
• /
• 2019

Numerous privacy-preserving authentication schemes have been proposed but vehicular ad hoc networks (VANETs) still suffer from security and privacy issues as well as computation and communication overheads. In this paper, we proposed a robust conditional privacy-preserving authentication scheme based on pseudonym root with cuckoo filter to meet security and privacy requirements and reduce computation and communication overheads. In our proposed scheme, we used a new idea to generate pseudonyms for vehicles where each on-board unit (OBU) saves one pseudonym, named as "pseudonym root," and generates all pseudonyms from the same pseudonym. Therefore, OBU does not need to enlarge its storage. In addition, the scheme does not use bilinear pairing operation that causes computation overhead and has no certification revocation list that leads to computation and communication overheads. The proposed scheme has lightweight mutual authentication among all parties and just for once. Moreover, it provides strong anonymity to preserve privacy and resists ordinary attacks. We analyzed our proposed scheme and showed that it meets security and privacy requirements of VANETs and is more efficient than traditional schemes. The communication and computation overheads were also discussed to show the cost-effectiveness of the proposed scheme.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.24 no.6
• /
• pp.1147-1157
• /
• 2014

Intelligent transportation system (ITS) is realized through a highly ephemeral network, i.e. vehicular ad hoc network (VANET) which is on its way towards the deployment stage, thanks to the advancements in the automobile and communication technologies. However, it has not been successful, at least to date, to install the technology in the mass of vehicles due to security and privacy challenges. Besides, the users of such technology do not want to put their privacy at stake as a result of communication with peer vehicles or with the infrastructure. Therefore serious privacy measures should be taken before bringing this technology to the roads. To date, privacy issues in ephemeral networks in general and in VANET in particular, have been dealt with through various approaches. So far, multiple pseudonymous approach is the most prominent approach. However, recently it has been found out that even multiple pseudonyms cannot protect the privacy of the user and profilation is still possible even if different pseudonym is used with every message. Therefore, another privacy-aware mechanism is essential in vehicular networks. In this paper, we propose a novel identity exchange mechanism to preserve conditional privacy of the users in VANET. Users exchange their pseudonyms with neighbors and then use neighbors' pseudonyms in their own messages. To this end, our proposed scheme conditionally preserves the privacy where the senders of the message can be revoked by the authorities in case of any dispute.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.18 no.5
• /
• pp.115-124
• /
• 2008

In vehicular networks, vehicles should be able to authenticate each other to securely communicate with network-based infrastructure, and their locations and identifiers should not be exposed from the communication messages. however, when an accident occurs, the investigating authorities have to trace down its origin. As vehicles communicate not only with RSUs(Road Side Units) but also with other vehicles, it is important to minimize the number of communication flows among the vehicles while the communication satisfies the several security properties such as anonymity, authenticity, and traceability. In our paper, when the mutual authentication protocol is working between vehicles and RSUs, the protocol offers the traceability with privacy protection using pseudonym and MAC (Message Authentication Code) chain. And also by using MAC-chain as one-time pseudonyms, our protocol does not need a separate way to manage pseudonyms.

• Journal of Korea Multimedia Society
• /
• v.18 no.4
• /
• pp.499-505
• /
• 2015

Security supports are a significant factor in the design of mobile ad hoc networks. In the dynamic topology where the node changes frequently, private key generation and revocation for newly joining and leaving nodes must be considered. In addition, the identities of individual nodes must be protected as well in mobile networks to avoid personal privacy concerns. This paper proposes ID-based private key revocation scheme and non-interactive key agreement scheme in anonymous MANETs. The proposed scheme provides the user privacy using pseudonyms and private key generation and revocation schemes with consideration of dynamic user changes. Therefore, our schemes can be applied in dynamic and privacy-preserving MANETs which are helpful to share multimedia data.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.15 no.1
• /
• pp.65-68
• /
• 2005

Privacy preservation is crucial in ubiquitous computing environment in which lots of privacy- sensitive information can be collected and distributed without appropriate control. The anonymity-based approach is a famous one used for privacy preservation communication, which allows users to use pseudonyms instead of real ID so as not to reveal their identities. This approach is effective in that it can hide the identity of users. However, it makes it difficult to provide ID-based services like buddy service, dangerous area alert, P2P communication in the ubiquitous computing. We proposes a system architecture which enables ID-based services in the ubiquitous computing environment employing anonymity - based privacy - preserving approach.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.19 no.1
• /
• pp.33-42
• /
• 2009

Recently, there have been many researches about anonymous credential systems for supporting the user anonymity. However, these systems only hold a high security level, even though they must be able to be applied to various application that might require access control, conditional traceability, etc. As new challenges to these systems, some researches that several entities store the link information that associates identities and pseudonyms each other have been performed. In this paper, based on the oblivious transfer, we suggest a new pseudonym protocol that solves the pseudonym exhaustion problem which the original pseudonym retrieval protocol suffers from. By using the universal re-encryption and one-way function, we can also archive other requirements like the pseudonym unlinkability from the outside.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.31 no.1
• /
• pp.11-17
• /
• 2021

Due to the recent development of the Internet of Things (IoT) and the increase in services using drones, research on IoD is actively underway. Drones have limited computational power and storage size, and when communicating between drones, data is exchanged after proper authentication between entities. Drones must be secure from traceability because they contain sensitive information such as location and travel path. In this paper, we point out a fatal security vulnerability that can be caused by the use of pseudonyms and certificates in existing IoD research and propose a solution.