Due to their frequent use in unattended and hostile deployment environments, the security in wireless sensor networks (WSNs) has attracted much interest in the past two decades. However, it remains a challenge to design a lightweight authentication protocol for WSNs because the designers are confronted with a series of desirable security requirements, e.g., user anonymity, perfect forward secrecy, resistance to de-synchronization attack. Recently, the authors presented two authentication schemes that attempt to provide user anonymity and to resist various known attacks. Unfortunately, in this work we shall show that user anonymity of the two schemes is achieved at the price of an impractical search operation—the gateway node may search for every possible value. Besides this defect, they are also prone to smart card loss attacks and have no provision for perfect forward secrecy. As our main contribution, a lightweight anonymous authentication scheme with perfect forward secrecy is designed, and what we believe the most interesting feature is that user anonymity, perfect forward secrecy, and resistance to de-synchronization attack can be achieved at the same time. As far as we know, it is extremely difficult to meet these security features simultaneously only using the lightweight operations, such as symmetric encryption/decryption and hash functions.

On-body wireless networks (oBWNs) play a crucial role in improving the ubiquitous healthcare services. Using oBWNs, the vital physiological information of the patient can be gathered from the wearable sensor nodes and accessed by the authorized user like the health professional or the doctor. Since the open nature of wireless communication and the sensitivity of physiological information, secure communication has always been the vital issue in oBWNs-based systems. In recent years, several authentication schemes have been proposed for remote patient monitoring. However, most of these schemes are so susceptible to security threats and not suitable for practical use. Specifically, all these schemes using lightweight cryptographic primitives fail to provide forward secrecy and suffer from the desynchronization attack. To overcome the historical security problems, in this paper, we present a lightweight and secure three-factor authentication scheme for remote patient monitoring using oBWNs. The proposed scheme adopts one-time hash chain technique to ensure forward secrecy, and the pseudonym identity method is employed to provide user anonymity and resist against desynchronization attack. The formal and informal security analyses demonstrate that the proposed scheme not only overcomes the security weaknesses in previous schemes but also provides more excellent security and functional features. The comparisons with six state-of-the-art schemes indicate that the proposed scheme is practical with acceptable computational and communication efficiency.

Multi-server authentication technology has become more and more popular with the extensive applications of networks. Although it has brought great convenience to people’s life, security becomes a critical issue and attracts lots of attentions in both academia and industry. Over the past two decades, a series of multi-server authentication schemes without communication with the online registration center in each authentication phase using the self-certified public key cryptography have been proposed to enhance security. However, it may cause the single-point failure problem due to the centralized architecture. Besides, user revocation facility is not well resolved in these schemes. To the best of our knowledge, blockchain technology has lots of advantages, bringing a promising solution to the problems of single-point failure and user revocation compared with the traditional cryptography technologies. In this work, we apply the idea of blockchain technology to construct a privacy-awareness authentication scheme for the multi-server environment, which can achieve distributed registry and efficient revocation. Moreover, the proposed scheme not only provides multiple security requirements like mutual authentication, user anonymity and perfect forward secrecy, but also resists various kinds of malicious attacks. The security of the proposed scheme is proved by rigorous formal proof using the random oracle model. Compared with recently related schemes, the proposed scheme has better communication performance, which make it be very suitable for real-life applications.

Authentication and authorization constitute the essential security component, access control, for preventing unauthorized access to cloud services in mobile cloud computing (MCC) environments. Traditional centralized access control models relying on third party trust face a critical challenge due to a high trust cost and single point of failure. Blockchain can achieve the distributed trust for access control designs in a mutual untrustworthy scenario, but it also leads to expensive storage overhead. Considering the above issues, this work constructed an authentication and authorization scheme based on blockchain that can provide a dynamic update of access permissions by utilizing the smart contract. Compared with the conventional authentication scheme, the proposed scheme integrates an extra authorization function without additional computation and communication costs in the authentication phase. To improve the storage efficiency and system scalability, only one transaction is required to be stored in blockchain to record a user’s access privileges on different service providers (SPs). In addition, mobile users in the proposed scheme are able to register with an arbitrary SP once and then utilize the same credential to access different SPs with different access levels. The security analysis indicates that the proposed scheme is secure under the random oracle model. The performance analysis clearly shows that the proposed scheme possesses superior computation and communication efficiencies and requires a low blockchain storage capacity for accomplishing user registration and updates.

Nowadays, the research of tradeoff between reliance on the tamper-proof device(TPD) and storage space in authentication scheme has become an interesting topic for vehicular ad hoc networks(VANETs). Most recently, to minimize the dependencies of TPDs and reduce the storage space, Zhang et al. proposed a conditional privacy-preserving authentication scheme based on multiple trusted authority one-time identity-based aggregate signature technique. It is more practical than other related schemes due to not depending on ideal TPDs. However, Zhang et al.’s scheme requires a fully trusted third party to participate in the authentication and member secrets generate phase, which may suffer from security bottleneck. To overcome this weakness, in this work, we construct a realistic distributed conditional privacy-preserving authentication scheme for VANETs using identity-based cryptography and short lifetime region-based certificate. Comparing with Zhang et al.’s scheme, the proposed scheme has more security features but doesn’t reduce computation and communication efficiency. The security analysis shows that our scheme is provably secure in the random oracle model.