In healthcare wireless sensor networks (HWSNs), a patient's body usually contains several wearable or implantable wireless sensors which generate and transmit physiological data to a medical server (MS) where authorised medical professionals can access relevant medical data for efficient patient's diagnosis and treatments. To achieve data integrity and authenticity, aggregate signature is generally used. Several certificateless aggregate signature (CL-AS) schemes have been proposed to address the problems in the traditional public key cryptography. However, the performances of the existing CL-AS schemes are sometimes unsatisfactory. In this work, we propose a novel pairing-free certificateless aggregate signature scheme with strong anonymity for HWSN. We show that the scheme is provably secure against Type I and Type II adversaries in the random oracle model based on the elliptic curve discrete logarithm problem (ECDLP) assumption. The performance analysis and comparison show that the scheme is very efficient in terms of computation and communication overhead.

In smart grids (SGs), smart meters (SMs) are usually deployed to collect and transmit customers' electricity consumption data in real-time to the control center. Due to the open nature of the SG communication, several privacy-preserving data aggregation schemes have been proposed to protect the privacy of customers. However, most of these schemes cannot protect against internal attackers and they are not efficient, since SMs are constrained in processing, memory, and computing capabilities. To address these problems, the authors propose a privacy-aware lightweight data aggregation scheme against internal attackers based on Elliptic Curve Cryptography (ECC). The scheme satisfies all the security requirements of SG, and supports conditional traceability, strong anonymity and autonomy. The authors demonstrate that the proposed scheme provides confidentiality based on the Computational Diffie-Hellman (CDH) assumption and unforgeability in the security model based on the intractability of the Discrete Logarithm (DL) problem. Extensive performance analysis shows that the proposed scheme is very efficient.