242

S. Das et al.

surface is expanded and to improve the attack threshold the hardware is utilized.

The research [26] proposed a lightweight blockchain called Sensor Chain, which

is a large global blockchain divided into local blockchains. Sensor Chain requires

much less storage space than a normal blockchain and optimizes blockchain with

respect to memory space requirement and latency. A mechanism based on credit,

and alliance chain-based credit evaluation was proposed named, practical Byzantine

fault-tolerant (PBFT) consensus mechanism and a lightweight consistency protocol

is utilized. A modified checkpoint protocol enables the nodes to dynamically enter or

leave the system. In the research [27] the authors have proposed an algorithm, called

the Ouroboros algorithm. This algorithm aims to prevent attacks caused by selfish

mining by demonstrating the Nash equilibrium by the non-malicious nodes in the

network. This is performed after a consensus algorithm that forms a Proof-of-Stake

algorithm is generated by an incentive system. The other algorithm is a Proof-of-

Work algorithm based on the famous “generalized birthday paradox” named the

Equihash algorithm. It determines the workload by calculating the memory required

from the sizes of the nodes since it is a memory-dependent algorithm. Though the

algorithm demands a good amount of space it achieves immediate verification. It

improves the cost-effectiveness of the ASCI hardware. A private immutable ledger,

designed in the research [28] acts as a blockchain but is managed centrally. The

devices with greater resources implement a publicly accessible distributed system.

From the above literature review, it is worth marking that lightweight blockchain

has the potential to successfully merge IIoT technology with blockchain [29]. We

conclude that some developments in lightweight blockchain architecture have been

done. Some have built reinforcement learning in blockchain [30] to provide rapid

adoption of blockchain technology. And others have designed a lightweight hash-

based blockchain for resource-constrained devices to reduce the computational

burden and block creation latency [31]. Existing systems also sometimes lack the

potential to find an efficient and optimized blockchain design to secure the IIoT

network. The motivation of the work is not only to design an efficient hash functioned

blockchain but also optimally use the computing resources of IIoT devices.

However, even though lightweight cryptographic hash algorithms have a lot of

potential use cases in IIoT, they all share some glaring issues like a significant lack

of bandwidth, lack of software support as well as being generally more vulnerable

compared to more robust cryptographic hash algorithms. Especially more compu-

tationally capable devices in the IIoT network, where high bandwidth is necessary,

just using lightweight blockchain can be contra-productive to the efficiency of the

network. As such, there is the need for a more efficient architecture that merges

the advantages of both lightweight cryptography and non-lightweight cryptography

to avoid a bandwidth bottleneck while also taking into account the computational

powers of the devices in the IIoT network.