IoT Gateways as Blockchain Nodes

IoT gateways can function either as a full BN or a thin client. An IoT gateway can route data and verify integrity of data when it functions as a full BN. If used as a thin client, an IoT gateway stores only a few relevant data parts. Mehedi et al. [30] proposed a reliable and polished blockchain-IoT infrastructure, which represents a change from centralized systems and memory overheads while maintaining privacy and security effectively. They used the standard IoT infrastructure along with decentralized blockchain technology for storing and accessing the data. For integration of blockchain and IoT. they used Ethereum as a blockchain platform and terminal devices enlisting the network technology. Whenever a request is made for storing a transaction, the proposed approach uses the distributed ledger, which gets executed and stored on its own. To protect the users’ identities, the terminal devices are organized in a better way. Loukil et al. [31] designed a semantic IoT gateway that improved control over the private resources along with providing protection for collected personal data. This is done by first matching the terms and conditions of service at the customer’s end with the privacy preferences at the data owner’s end and then inducing a policy adaptable to the described conditions. This privacy policy is converted into smart contracts. Then, in order to host the generated smart contracts, the set of resources are connected to a decentralized network using blockchain technology. There are nine core components of this blockchain framework, namely public IoT network, private IoT network, public blockchain, smart contract, private ledger, transaction, semantic IoT gateway, storage node, and local storage. The semantic IoT gateway binds together the blockchain network, the actuators, and the IoT terminals. When the experiment was performed in the real world, use-case data showed positive results and proved that custom-generated smart contracts can be added to the blockchain technology with a high success rate.

A credit-based mechanism has been proposed by Huang et al. [32] that ensures better efficiency for simultaneous transactions and confirms system security. For ensuring the confidentiality of sensitive data, a mechanism for managing the data authority is defined that controls the sensor data access. The mechanism is designed on structured blockchain based on directed acyclic graphs, which gives better performance and improved throughput compared with chain-structured blockchain like Satoshi-style blockchain. The case study was conducted for a smart factory and the system was implemented on Raspberry Pi 3 Model B. The architecture design of a smart factory consists of four major components, namely tangle network, wireless sensors, managers, and gateways. The designed architecture is impenetrable to various attacks such as DoS, distributed denial-of-service (DDoS), and Sybil. Sybil attacks generally occur in a peer-to-peer network where the attacker creates multiple active identities to hugely influence the network. To guarantee the optimal trade-off between system security and transactional efficiency, a proof-of-work mechanism has been designed, which ensures that the honest nodes always devour a limited number of resources while enforcing the malicious nodes with increased attack cost. To ensure confidentiality, the authors designed a mechanism for data authority management in which the nodes that collect sensitive data are given the secret key by managers, and with the help of this key, sensor data is encrypted before being posted on the blockchain.

Biswas et al. [33] have used a network of local peers which narrows the gap between blockchain peers and IoT devices. Without affecting the transactional validation policy followed by peers at both the local and global level, the number of transactions entering the global blockchain is restricted using a local ledger.

The authors proposed a framework based on blockchain technology for IoT which considers both the inter and intra transactions for the corresponding organization. Each IoT device is registered by the certification authority and associated with one of the organizations. Instead of using peers belonging to a global blockchain, a local peer was structured to achieve the interaction with peers belonging to global block- chain network. The designed framework aims to handle the indirect rise in transactions per second for the global blockchain network and increase in ledger storage requirements at peer level. The size of ledger is limited under this framework and is distributed between local and global peers. The transactions between two organizations are validated via a global blockchain network that provides 100% peer validation. In this work, they clearly demonstrated that if the issue of scalability is not addressed, blockchain and IoT cannot be integrated, and that creating a network of local peers allowed the blockchain ledger to spread across all the peers and hence improved scalability.

A blockchain connected gateway is designed by Cha et al. [34] to maintain the privacy preference of IoT devices securely and adaptively within the blockchain network. It can prevent the leakage of sensitive data by ensuring that the data is not accessed without the user’s permission. There are three major participants in the proposed framework, namely the IoT device administrator, gateway administrator, and end user. The IoT device administrator stores the device information along with the device’s privacy policy at the blockchain network before the user gains access to it. The list of attributes uploaded on the blockchain network includes the device’s name, manufacturer’s information, device description, and device images list, and the privacy policy includes information related to preference, policy identifier, and so on. The signature scheme proposed by the authors is robust and has interacting skills similar to DLP based on elliptical curves. Each security component of this signature scheme has been implemented and tested on Raspberry Pi 3 Model В and the computational cost for each security component has been calculated. The results show that while legacy devices are in use, the proposed framework increases the trust among IoT applications and improves user privacy.

Badr et al. [35] designed a novel protocol named pseudonym based on encryption for providing privacy to patients’ data available in the e-healthcare system. The encryption mechanism is blockchain-based in which high-end different authority encryption techniques are used for securing the patients’ confidential data. The public blockchain tier between the healthcare cloud providers and the blockchain tier handling the sensors on patients’ bodies along with the patients’ system on the platform are considered in this approach. The work elevates the anonymity factor in patients’ data by considering blockchain as the anonymity enhancement technology using the multitier architectural model which prevents the system from various attacks such as block enquiry infringement. The solution was evaluated using the MIRACL library, which keeps track of the processing time for all the functions executing within the communication channel. The architecture contains three tiers, where the first tier shows how all the sensor devices are connected to the patient through a gateway or aggregator. The second tier analyses the distribution of the ledger and handles communication within the health record members and provider. In tier three, compliance with the cloud providers is considered and analysed. This framework can handle some of the security vulnerabilities but not all. Therefore, in the future, this model should be modified to handle larger clusters of security issues.