Biblio

Research into the established area of ITS is evolving into the Internet of Vehicles (IoV), itself a fast-moving research area, fuelled in part by rapid changes in computing and communication technologies. Using pseudonym certificate is a popular way to address privacy issues in IoV. Therefore, the certificate management scheme is considered as a feasible technique to manage system and maintain the lifecycle of certificate. In this paper, we propose an efficient pseudonym certificate management scheme in IoV. The Blockchain concept is introduced to simplify the network structure and distributed maintenance of the Certificate Revocation List (CRL). The proposed scheme embeds part of the certificate revocation functions within the security and privacy applications, aiming to reduce the communication overhead and shorten the processing time cost. Extensive simulations and analysis show the effectiveness and efficiency of the proposed scheme, in which the Blockchain structure costs fewer network resources and gives a more economic solution to against further cybercrime attacks.

In this paper, we propose a conditional privacy-preserving authentication scheme based on pseudonyms and (t,n) threshold secret sharing, named CPPT, for vehicular communications. To achieve conditional privacy preservation, our scheme implements anonymous communications based on pseudonyms generated by hash chains. To prevent bad vehicles from conducting framed attacks on honest ones, CPPT introduces Shamir (t,n) threshold secret sharing technique. In addition, through two one-way hash chains, forward security and backward security are guaranteed, and it also optimize the revocation overhead. The size of certificate revocation list (CRL) is only proportional to the number of revoked vehicles and irrelated to how many pseudonymous certificates are held by the revoked vehicles. Extensive simulations demonstrate that CPPT outperforms ECPP, DCS, Hybrid and EMAP schemes in terms of revocation overhead, certificate updating overhead and authentication overhead.

Public Key Infrastructure (PKI) has been popularized in many scenarios such as e-government applications, enterprises, etc. Due to the construction of PKI system of various regions and departments, there formed a lot of isolated PKI management domains, cross-domain authentication has become a problem that cannot ignored, which also has some traditional solutions such as cross-authentication, trust list, etc. However, some issues still exist, which hinder the popularity of unified trust services. For example, lack of unified cross domain standard, the update period of Certificate Revocation List (CRL) is too long, which affects the security of cross-domain authentication. In this paper, we proposed a trust transferring model by using blockchain consensus instead of traditional trusted third party for e-government applications. We exploit how to solve the unified trust service problem of PKI at the national level through consensus and transfer some CA management functions to the blockchain. And we prove the scheme's feasibility from engineering perspective. Besides, the scheme has enough scalability to satisfy trust transfer requirements of multiple PKI systems. Meanwhile, the security and efficiency are also guaranteed compared with traditional solutions.

When relying on public key infrastructure (PKI) for authentication, whether a party can be trusted primarily depends on its certificate status. Bob's certificate status can be retrieved by Alice through her interaction with Certificate Authority (CA) in the PKI. More specifically, Alice can download Certificate Revocation List (CRL) and then check whether the serial number of the Bob's certificate appears in this list. If not found, Alice knows that Bob can be trusted. Once downloaded, a CRL can be used offline for arbitrary many times till it expires, which saves the bandwidth to an extreme. However, if the number of revoked certificates becomes too large, the size of the CRL will exceed the RAM of Alice's device. This conflict between bandwidth and RAM consumption becomes even more challenging for the Internet-of-Things (IoT), since the IoT end-devices is usually constrained by both factors. To solve this problem in PKI-based authentication in IoT, we proposed two novel lightweight CRL protocols with maximum flexibility tailored for constrained IoT end-devices. The first one is based on generalized Merkle hash tree and the second is based on Bloom filter. We also provided quantitative theorems for CRL parameter configuration, which help strike perfect balance among bandwidth, RAM usage and security in various practical IoT scenarios. Furthermore, we thoroughly evaluated the proposed CRL protocols and exhibited their outstanding efficiency in terms of RAM and bandwidth consumption. In addition, our formal treatment of the security of a CRL protocol can also be of independent interest.

Advanced Metering Infrastructure (AMI) forms a communication network for the collection of power data from smart meters in Smart Grid. As the communication within an AMI needs to be secure, key management becomes an issue due to overhead and limited resources. While using public-keys eliminate some of the overhead of key management, there is still challenges regarding certificates that store and certify the public-keys. In particular, distribution and storage of certificate revocation list (CRL) is major a challenge due to cost of distribution and storage in AMI networks which typically consist of wireless multi-hop networks. Motivated by the need of keeping the CRL distribution and storage cost effective and scalable, in this paper, we present a distributed CRL management model utilizing the idea of distributed hash trees (DHTs) from peer-to-peer (P2P) networks. The basic idea is to share the burden of storage of CRLs among all the smart meters by exploiting the meshing capability of the smart meters among each other. Thus, using DHTs not only reduces the space requirements for CRLs but also makes the CRL updates more convenient. We implemented this structure on ns-3 using IEEE 802.11s mesh standard as a model for AMI and demonstrated its superior performance with respect to traditional methods of CRL management through extensive simulations.

Public Key Regime (PKR) was proposed as an alternative to certificate based PKI in securing Vehicular Networks (VNs). It eliminates the need for vehicles to append their certificate for verification because the Road Side Units (RSUs) serve as Delegated Trusted Authorities (DTAs) to issue up-to-date public keys to vehicles for communications. If a vehicle's private/public key needs to be revoked, the root TA performs real time updates and disseminates the changes to these RSUs in the network. Therefore, PKR does not need to maintain a huge Certificate Revocation List (CRL), avoids complex certificate verification process and minimizes the high latency. However, the PKR scheme is vulnerable to Denial of Service (DoS) and collusion attacks. In this paper, we study these attacks and propose a pre-authentication mechanism to secure the PKR scheme. Our new scheme is called the Secure Public Key Regime (SPKR). It is based on the Schnorr signature scheme that requires vehicles to expend some amount of CPU resources before RSUs issue the requested public keys to them. This helps to alleviate the risk of DoS attacks. Furthermore, our scheme is secure against collusion attacks. Through numerical analysis, we show that SPKR has a lower authentication delay compared with the Elliptic Curve Digital Signature (ECDSA) scheme and other ECDSA based counterparts.