The Internet of Medical Things (IoMT) builds a bridge between patients and doctors, facilitating patients’ being diagnosed and monitored by uploading physiological indicators without visiting the hospital. However, physiological indicators are sensitive data of patients, making it a challenge to achieve verifiability of data sources while ensuring data privacy during data transmission of IoMT. Due to its ease of deployment and the ability to provide both encryption and signature, certificateless signcryption (CLSC) is suitable for designing secure data-transfer protocol in IoMT. Nevertheless, internal adversaries “malicious users” and “malicious KGC,” capable of launching Type I and Type II attacks, threaten the security of present CLSC schemes, making most of them insecure. In this work, after giving an example of a recent CLCS scheme suffering Type I attack, we propose an efficient pairing-free CLCS scheme suitable for secure data transmission in IoMT based on the idea of zero-knowledge proof. It not only provides confidentiality and unforgeability of transmitted data under the Type I and Type II attacks but also achieves lower computational and communication overhead, and public verifiability. Finally, compared with the five recent CLSC schemes, theoretical analysis and experimental testing results show that the proposed scheme outperforms the other five schemes in terms of computation and communication costs as well as security. Therefore, our scheme is better suited for constructing secure data transmission in IoMT scenarios.

In Wireless body area networks(WBANs), the physiological parameters monitored by wearable devices are sensitive data of patients. To ensure the privacy of such data, Shenet alproposed a multi-receiver certificateless generalized signcryption scheme to support multidisciplinary team treatment. Although they claim that their scheme can resist Type I attacks and provide the unlinkability of ciphertext, our analysis found that their scheme is insecure. Specifically, it is neither resistant to public key replacement in Type I attacks, nor does it satisfy the claimed unlinkability of ciphertext. After giving the corresponding attacks, we analyze the reasons underlying these attacks and provide the corresponding suggestions to overcome them.

Recently, to eliminate complex certificate maintenance and key escrow issue, Verma et al. proposed the first certificate-based(CB-based) data aggregation scheme for smart grids, in which a lightweight CB-based signature is proposed to ensure the integrity of the transmitted data. Although they claimed that the proposed certificate-based signature scheme is secure against attacks by a malicious certification authority (CA), unfortunately, by analyzing the security of Verma et al.'s scheme, we show that their scheme is insecure. It can not provide data integrity since a malicious CA can forge a message's signature in the name of any entity. After giving the corresponding attacks, we analyze the reasons for producing such attacks and provide the corresponding suggestions to overcome them.

With the advancement of cryptocurrencies, hierarchical deterministic wallets (HDW) are widely used due to their advantages of easy backup, offline storage, and convenient address management. However, most present HDW schemes are vulnerable to privilege escalation attacks, which pose a tremendous risk to user privacy. As an effective technique for protecting user identity privacy, stealth addresses allow payers to generate a unique address for each transaction in a noninteractive manner. Integrating stealth addresses into HDW can help improve the security of HDW schemes. Based on the above idea, we propose a novel lightweight Hierarchical Deterministic Wallet Supporting Stealth Address (HDWSA) scheme, which not only provides all standard wallet functions but also guarantees the privacy of user identities. Since the proposed scheme is based on the generic elliptic curve cryptosystem, time-consuming pairing operations are avoided, which makes it directly applicable to the current blockchain structure. Finally, the new scheme is proven to be secure in the random oracle.