Secure and scalable blockchain mechanisms for IoT applications

Abstract

Integrating blockchain with IoT ensures secure, transparent data exchange through immutability and consensus mechanisms, preventing data tampering. However, the increasing number of IoT devices raises risks like unauthorized access and network attacks. Blockchain scalability issues also affect throughput and latency, challenging real-time IoT applications. This thesis addresses these challenges through four contributions that aim to improve the security, scalability, and efficiency of blockchainbased IoT networks, balancing security with performance needs. Our first contribution is to develop an end-to-end security mechanism for IoT networks, called the trust-based ABAC mechanism for IoT networks (TABI). TABI integrates edge computing and blockchain technology to mitigate risks from malicious devices and offload computational tasks to edge layers. It operates on Hyperledger Fabric (HLF), a permissioned blockchain that enhances throughput and latency through its executeorder- validate architecture. Our second objective is to provide scalability within blockchain-based IoT networks using a sidechain-based trust and access control system, named sidechain-based trust and access control mechanism for IoT networks (SATI). By distributing trust evaluation and access control operations across a separate blockchain or sidechain, SATI improves the scalability of IoT networks. We implement a cross-chain transfer mechanism to ensure communication between the sidechain and the mainchain, thus overcoming a fundamental limitation of traditional blockchain architectures. Our third contribution is to improve the security of the IoT network by introducing a Zero-Knowledge Proof-based Mutual Authentication (ZPMA) mechanism, a privacy-preserving mutual authentication mechanism. Utilizing Zero-Knowledge Proofs (ZKP) based on the quadratic residue technique, Z-PMA ensures secure and private mutual authentication between edge devices and IoT devices. We also implement an incentive mechanism to select additional authenticators from the base station layer to reduce authentication latency and support the demands of low-latency IoT networks. Our fourth contribution is to detect and resolve conflicting transactions in HLF-based IoT networks at an early stage, known as the early-stage conflict transaction resolution (ECR) mechanism. ECR identifies and resolves conflicting transactions at an early stage using a local cache at the endorsement phase of the HLF transaction processing. Additionally, ECR uses dependency model and an efficient reordering process to distribute transactions in a way that minimizes conflicts. This mechanism enhances the performance of HLF-based IoT networks by reducing the impact of conflicting transactions, ultimately improving throughput and latency.