Full Decentralized Privacy-Preserving Scheme for Data Access Control in Smart Consumer Electronic Devices for Medical IoT

Medical Internet of Things (MIoT) environments are rapidly expanding, providing a wide range of services that enhance human well-being through interconnected IoT and consumer healthcare devices capable of sensing, processing, and exchanging environmental and physiological data. However, the openness and scale of these networks introduce significant security challenges, particularly due to their reliance on centralized infrastructures. A single compromise of a trusted third party (TTP) or central service can threaten the entire system. Although several privacy-preserving solutions have been proposed, many still rely on TTPs for critical operations. In this paper, we propose a fully decentralized privacy-preserving scheme that ensures data self-sovereignty, transparency, and removes the need for TTP involvement. The scheme employs fine-grained access control, enabling precise management of permissions and strengthening both user autonomy and data protection for consumer healthcare devices in MIoT ecosystems. We conduct both formal and informal security analyses, as well as simulation-based validation of the proposed scheme. In addition, we implement the scheme on the Ethereum blockchain and perform comparative evaluations, demonstrating improvements in computational efficiency and security functionalities over existing approaches. This work addresses key security challenges in MIoT by combining full decentralization with fine-grained access control.