During the crisis of COVID-19, the need to stay at home has raised dramatically. In addition, the number of sick people, especially elderly persons, has increased exponentially. In such a scenario, home monitoring of patients can ensure remote healthcare at home using advanced technologies such as the Internet of Medical Things (IoMT). The IoMT can monitor and transmit sensitive health data, however, it may be vulnerable to various attacks. In this paper, an efficient healthcare security system is proposed for IoMT's applications. In the proposed system, the medical sensors can transmit sensed encrypted health data via a mobile application to the doctor for privacy. Then, three consortium blockchains are constructed for load balancing of transactions and reducing transaction latency. They store the credentials of system entities, doctor's prescriptions, and recommendations according to the data transmitted via mobile applications and the medical treatment process. Besides, cancelable biometrics are used for providing authentication and increasing the security of the proposed medical system. The investigational results show that the proposed system outperforms existing work where the proposed model consumed less processing time by values of 18%, 22%, and 40%, and less energy for processing a 200 KB file by values of 9%, 13%, and 17%. Finally, the proposed model consumed less memory usage by values of 7%, 7%, and 18.75%. From these results, it is clear the proposed system gives a very reliable and secure performance for efficiently securing medical applications.

Abstract In recent times, the new revolution of IoT facilitates communication and information sharing among people in different domains like a smart city. This revolution came with a risk of cyber‐attacks that target devices and shared data. The digital evidence resulting from the digital forensics process applied to IoT devices must be kept safe for later analysis. Preserving digital evidence on a centralized server raises the risk of a single point of failure. Evidence preserving on cloud servers raises the tampering risk with the evidence or even sharing them with malicious third parties. Therefore, this paper presents a novel framework called Forensics Chain for Evidence Preservation System for IoT ‐based smart city security. The proposed framework aims to integrate blockchain with digital forensics to overcome the problems faced by forensic investigators; single point of failure and/or evidence modifications and enhance the security of preserving digital evidence via applying blockchain. Applying blockchain guarantees the immutability and data integrity of the preserved evidence. Furthermore, preserving the digital evidence among the forensic participant nodes eliminates the possibility of the single‐point failure of a centralized storage server. The results provided a Proof of Concept for forensic evidence preservation based on blockchain and evaluated its performance.