Focusing on the problem that the privacy-preserving of identity authentication in Vehicular Ad Hoc NETworks (VANET), a conditional privacy-preserving authentication scheme was proposed. Firstly, this paper introduced the short signature technology, and then constructed a new identity-based short signature scheme. Compared with the well-known Conditional Privacy-Preserving Authentication Scheme (CPAS), the proposed scheme could reduce the computation costs required for both signature and verification processes and improve the communication efficiency. Secondly, the scheme divided the private signature key into two correlative sub-segments, so that it could effectively solve the issue of key escrow. Therefore, the scheme was especially suitable for the environment of VANET. Based on the proposed signature scheme, a conditional privacy-preserving authentication scheme was presented, which can achieve identity authentication with conditional privacy preservation. The theoretical and efficiency analysis shows that the scheme needs only three dot multiplication in the signature process and takes one dot multiplication, two pairing operation in the verification process. Especially, the proposed scheme use batch verification by adding the small coefficient test to accelerate the authentication speed and reduce the error rate.

With regard to the security vulnerabilities of the existing Radio Frequency Identification (RFID) authentication protocols, a new lightweight security protocol for RFID was proposed. The formal proof of the correctness of the proposed authentication protocol was given based on GNY logic. The proposed scheme adopted the method of reader dual-authentication and key refreshing during reader pre-authentication phase, which achieved the anti-desynchronization requirement by adding flag Tm of malicious attacks into the tag. The protocol solved the security and privacy problems of poor scalability, location tracking due to failure of renewing the key of tag, and Denial of Service (DoS) resulting from illegal updating inner keys of tag/server in the existed schemes. It efficiently resisted several possible attacks including replay, tag/reader impersonation, traffic analysis, location tracking and desynchronization. The analytical results show that the proposed protocol is of low-cost, good security and limited computational complexity, which fits for RFID system when the tags number is large.

The special nature of sensor network makes it vulnerable to Radio Frequency Jamming Attacks (RF JA) and other attacks. To implement and deploy the security mechanism of the next step, and determine the location of the Jamming attacker called jammer in Wireless Sensor Network (WSN), α-hull was applied to calculate the Minimum Circumscribed Circle (MCC) of point set. An effective and accurate method for MCC detection was established through finding the least square circle of the point set and iteratively approaching the MCC with recursive subdivision. All vertices of the α-hull will be on the same circle, if 1/α is equal to the radius of points' MCC. On the basis of those rules, an algorithm for detecting MCC named α-MCC was developed. The simulation results show that, compared with the existing incremental algorithm, α-MCC is able to achieve higher accuracy in most cases. With the network node density, time consumption of α-MCC does not grow exponentially, but with only a slight linear increase.