How to alleviate the contradiction between the patient's privacy and the research or commercial demands of health data has become the challenging problem of intelligent medical system with the exponential increase of medical data. In this paper, a blockchain-based privacy-preserving scheme is proposed, which realizes secure sharing of medical data between several entities involved patients, research institutions and semi-trusted cloud servers. And meanwhile, it achieves the data availability and consistency between patients and research institutions, where zero-knowledge proof is employed to verify whether the patient's medical data meets the specific requirements proposed by research institutions without revealing patients’ privacy, and then the proxy re-encryption technology is adopted to ensure that research institutions can decrypt the intermediary ciphertext. In addition, this proposal can execute distributed consensus based on PBFT algorithm for transactions between patients and research institutions according to the prearranged terms. Theoretical analysis shows the proposed scheme can satisfy security and privacy requirements such as confidentiality, integrity and availability, as well as performance evaluation demonstrates it is feasible and efficient in contrast with other typical schemes.

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As an emerging application of smart healthcare, mobile healthcare crowd sensing (MHCS) has become a research hotspot. However, how to ensure the confidentiality and integrity of data and protect the privacy of user is still a challenge for MHCS. To handle these issues, an effective and secure privacy protection scheme is indispensable. Recently, a large-scale concurrent data anonymous batch verification scheme for mobile healthcare crowd sensing was proposed by Liu et al. Unfortunately, we demonstrate that their scheme is insecure. This paper presents an improved anonymous scheme based on certificateless aggregate signature (CL-AS) for MHCS. First, considering the efficiency and the characteristics of the MHCS, the technique of aggregate signature is adopted, which can achieve batch verification and greatly save the bandwidth and computation resources. Second, anonymous communication is carried out in this scheme to realize privacy preservation. Third, based on certificateless cryptography, the proposed scheme can simplify the complicated certificate management and eliminate the key escrow problem. In addition, our scheme is provably secure against the existential forgery on adaptively chosen message attack in the Random Oracle Model assuming the computational Diffie-Hellman problem is intractable. Furthermore, security and efficiency analysis shows that our scheme is secure and efficient. INDEX TERMS Mobile healthcare crowd sensing, signature, certificateless cryptography, privacy preservation.

The Internet of Things (IoT) has built an information bridge between people and the objective world, wherein wireless sensor networks (WSNs) are an important driving force. For applications based on WSN, such as environment monitoring, smart healthcare, user legitimacy authentication, and data security, are always worth exploring. In recent years, many multifactor user authentication schemes for WSNs have been proposed using smart cards, passwords, as well as biometric features. Unfortunately, these schemes are revealed to various vulnerabilities (e.g., password guessing attack, impersonation attack, and replay attack) due to nonuniform security evaluation criteria. Wang et al. put forward 12 pieces of widely accepted evaluation criteria by investigating quantities of relevant literature. In this paper, we first propose a lightweight multifactor authentication protocol for multigateway WSNs using hash functions and XOR operations. Further, BAN logic and BPR model are employed to formally prove the correctness and security of the proposed scheme, and the informal analysis with Wang et al.’s criteria also indicates that it can resist well-known attacks. Finally, performance analysis of the compared schemes is given, and the evaluation results show that only the proposed scheme can satisfy all 12 evaluation criteria and keep efficient among these schemes.

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