# A Survey on Emerging Blockchain Technology Platforms for Securing the Internet of Things
###### Abstract  
The adoption of blockchain platforms to bolster the security of Internet of Things (IoT) systems has attracted significant attention in recent years. Currently, there is a lack of comprehensive and systematic survey papers in the literature addressing these platforms. This paper discusses six of the most popular emerging blockchain platforms adopted by IoT systems and analyses their usage in state-of-the-art works to solve security problems. The platform was compared in terms of security features and other requirements. Findings from the study reveal that most blockchain components contribute directly or indirectly to IoT security. Blockchain platform components such as cryptography, consensus mechanism, and hashing are common ways that security is achieved in all blockchain platform for IoT. Technologies like Interplanetary File System (IPFS) and Transport Layer Security (TLS) can further enhance data and communication security when used alongside blockchain. To enhance the applicability of blockchain in resource-constrained IoT environments, future research should focus on refining cryptographic algorithms and consensus mechanisms to optimise performance and security. blockchain; Internet of Things (IoT); cryptography; consensus algorithm; ethereum; algorand; IoTeX; IoTA; multichain +
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[PERSON] et al. [12] proposed different categorisations of IoT system components, including three-, four-, and five-layer models, respectively. However, all three models concur on the existence of fundamental components within the IoT system, such as the Application, Network, and Perception/device-sensing layers. Additional models may include layers such as the middleware layer and the business layer, as shown in Figure 2.  
IoT systems face several challenges. [PERSON] et al. [13] categorised these challenges into privacy and security, interoperability, scalability, heterogeneity, naming, and addressing. Among these challenges, privacy and security stand out as the primary concerns in IoT,  
Figure 1: Rise in connected devices [9]. Figure 2: IoT system layers. with many of them manifesting at the network layer [13]. In 2021, statistics on IoT attack revealed a disturbingly high frequency of cyber attacks, numbered in the billions. This underscores the need for stringent measures to safeguard IoT networks and protect user information [14]. [PERSON] et al. [15] classified attacks on IoT systems into Goal-oriented, performer-oriented, and layer-oriented. These attacks have been a significant source of insecurity in IoT systems. Various technologies including artificial intelligence and blockchain have been deployed to address these threats [15]. The current work focuses on blockchain. Blockchain is generally referred to as a tamper-proof distributed ledger that is immutable and securely linked by cryptographic hashing [16]. Each block contains a unique value called a nonce, which can only be used once. It also includes data, which represent the transactions saved on the blockchain, and a hash, which is a mathematical function that converts a variable-length (generally large) input string into a fixed-length output string. Blockchain technology has revolutionised the security and privacy of applications and devices by creating an interconnected and decentralised system that uses blocks to store information [17; 18]. Figure 3 shows the components of a blockchain. Blockchain transactions are managed using a wallet and are protected by digital signatures. These transactions are temporally saved in the mempool until it is nominated and agreed upon via consensus to be added to the blockchain. Blockchains provide a new mode of distributed data storage, point-to-point transmission, consensus mechanisms, and encryption, with features such as decentralisation, openness, tamper-proofing, anonymity, and traceability [19].