HyBloSE: Hybrid blockchain for secure-by-design smart environments

Although smart environments are a key component of the Internet of Things (IoT), it is also clear that billions connected doors, washing machines, ovens and others will ultimately raise security and privacy concerns. Early work in this area, as well as most of commercial solutions, has adopted a centralized client/server approach, neglecting the multitude of risks that are induced by an unfair control of the server side. This has made the adoption of a decentralized and trust-less framework quintessential to guarantee devices security. Nevertheless, decentralized proposals are hardly applicable due to costs, slowness and privacy issues. In this paper, we make the use of blockchain practical for smart environments by designing HyBloSE, a secure-by-design and lightweight blockchain-based framework, able to run on low-power devices without additional hardware. HyBloSE is built by using Delegated Proof of Authority and a Moving Window Blockchain. We evaluate HyBloSE through a network emulator and real experiments with different Raspberry Pi platforms. Results show that HyBloSE guarantees a higher security level in terms of resiliency to internal and external attacks compared to centralized solutions, with overhead below 0.38s per operation and less than $4 per month for unlimited operations. Furthermore, we show how Proof of Authority is more adapt then Proof of Work in IoT private scenarios.