# A Survey on Emerging Blockchain Technology Platforms for Securing the Internet of Things
###### Abstract
The effectiveness of blockchain technology in ensuring security, privacy, and reliability is well-established, which has led to its adaptation in various fields, including finance, e-government, IoT, public services, and supply chains. Numerous studies have delved into security and privacy issues in blockchain technology. Determining the most suitable blockchain type for an IoT ecosystem continues to pose a significant challenge in the field. This difficulty arises primarily from the inherent resource limitations of certain IoT devices, which require a careful consideration of the technology's adaptability. Consequently, the industry has witnessed the emergence of specialised solu  
Figure 3: Blockchain framework components. blockchain for IoT and half-node (pruned) blockchain for IoT [20]. These innovative approaches entail the deployment of either full-node (which takes part in all blockchain activities and stores all blocks) or pruned node (which only stores recent blocks and removes old blocks to manage storage space) blockchain structures within the IoT systems or the gateway of the IoT network, facilitating the seamless integration of blockchain technology with IoT devices [21]. As a result of this integration, the designated blockchain nodes are capable of collecting pertinent data from the IoT environment, which are then securely shared among the interconnected nodes within the blockchain network, enhancing the system's overall efficiency, security, and reliability. This has also invariably led to high resource consumption of such IoT systems [22]. This paper surveys emerging distributed ledger/blockchain platforms adopted to enhance security in IoT. It explore how these platforms can address vulnerabilities by securing data exchange between devices, managing device identities with tamper-proof mechanisms, and ensuring the integrity of transactions throughout the interconnected world of IoT. This is achieved by examining the frameworks, blockchain types, methodologies employed to ensure security at each layer of IoT, consensus algorithm, cryptography technology, and their limitations and strengths. The paper addresses the following research questions:  
1. What are the emerging blockchain technologies/platforms/frameworks used in IoT security, their components, and how have they been modified for resource-constrained IoT devices? 2. Which of the components above can work across all IoT devices without impacting security? 3. What other technology can boost the security of IoT when added to the blockchain with less or no impact on performance? To address these concerns, this study conducted a thorough search of related work on large database platforms via a digital library (Primo and Science Direct) and indexers (Google Scholar and SciSpace AI search assistance). A total of 14,745 journals were found using \"IoT Security using blockchain\". The results were filtered by removing duplicates, considering research work from high-profile research platforms (IEEE Xplore UK, ACM Digital Library US, Springer US, Elsevier Netherland, and MDPI Switzerland). The search was further screened by filtering with the following keywords: \"Blockchain\", \"IoT\", \"Blockchain IoT\", \"Blockchain IoT Security\", \"Blockchain Cryptography in IoT Security\", \"survey of blockchain IoT security\", \"review of IoT security with blockchain\", and \"Consensus Mechanism in Blockchain IoT security\", obtaining 1246 works. The results were assessed using their abstracts and methodology to select the 146 papers used in this work. Due to the systematic approach of this research, which considered works based on a definite blockchain platform used in IoT security, 46 works were examined under six blockchain platforms, 15 related works consisting of review and survey papers, and the rest of the papers were used to complement the research finding at different section of the paper.