CRT-based group rekeying with efficient dynamically aggregate signature for IoMT

In the realm of Internet of Medical Things (IoMT), patients suffering from similar symptoms are logically categorized into same groups. The medical server collects medical data from group members by utilizing IoMT devices. Aggregate signature for verifying large amounts of data can be significantly more efficient. However, the traditional aggregate signature fails to consider the dynamic nature group member in IoMT scenarios. The implementation of a static group token signature may present a security risk. To address the above pain points, we propose an Aggregate Signature with Group Rekeying (ASW-GR) scheme in IoMT. The ASW-GR utilizes the Chinese remainder theorem (CRT) and Fermat's little theorem to implement aggregate signature under group token update. It can achieve mutual authentication, conditional privacy-protection, forward and backward secrecy, and dynamic group token update. Meanwhile, we demonstrate that the ASW-GR is existentially unforgeable under the aggregated chosen-key security model. Utilizing the Java Pairing-Based Cryptography (JPBC) library, we conduct experiments demonstrating that the scheme is computationally efficient.