Distributed Anonymity Based on Blockchain in Vehicular Ad Hoc Network by Block Size Calibrating

The network connectivity problem is one of the critical challenges of an anonymous server implementation in the VANET. The objective and main contribution of this paper are to assure the anonymity in VANET environments. In the proposed blockchain method, before packaging transactions into blocks, anonymity risk reduced through techniques such as k-anonymity, graph processing, dummy node, and silence period. This paper addresses the challenges of anonymous servers, such as update challenges and single point of failure, by exploiting append-only, distributed, and anonymity features. Although mounting the blockchain process with asymmetric cryptography solves the connectivity challenge, start-up delay and network overhead are severe. The significant feature of the proposed method solves this delay challenge by aggregating many transactions into a block and fixing constraint range of multicasting blocks. Also, aggregating transactions of various end-users into a block preserves the path anonymity. The asymmetric cryptography with ring public and private keys protects the identity anonymity as well as unlinkability. The robust anonymity mechanism existence and the traceability of all transactions constitute the main advantages of the proposed method. The simulation is running by the python to evaluate blockchain performance in VANET with connectivity failure and rapidly changing topology. The results indicate the stabilization of the proposed method in the VANET environment

IMPROVED MCBDS FOR DEFENDING AGAINST GRAY HOLE AND BLACK HOLE ATTACKS IN MANETS

Mobile Ad-hoc Networks (MANETs) are widely used nowadays. Because of their characteristics as open media, dynamic topology, being infrastructure-less and lack of centralized monitoring, MANET is vulnerable to a wide range of attacks like blackhole and grayhole. Blackhole and grayhole attacks refer to the attacks that breach the security by performing packet forwarding and routing misbehavior and cause denial of service in MANETs. In this paper we improved our previous work on MCBDS, we reduced false-positive rate more than before and on average it dropped to zero. The proposed method employs Network Simulator-2 (NS-2) to validate the effectiveness under different scenarios. Simulation results show that improved MCBDS has same performance as CBDS in terms of throughput and end-to-end delay and as much as the presence of malicious nodes increased, improved MCBDS performs better than CBDS