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D. De et al.

• Storage

All blockchain nodes need to keep the entire blockchain data in their storage. Here

problem comes, maximum IoT device is lightweight and have limited storage.

Every IoT device cannot store this massive amount of data. So storage is a

considerable concern in the BC-IoT domain.

8

Limitation of Blockchain of Things

Some of the limitations of BCoT in the arena of Industry 5.0 are as follows.

• Quantum Computing

Blockchain security is mainly built on some difficult mathematical puzzles which

are extremely difficult for conventional computers to crack. However, ground-

breaking technology like quantum computing can break this extremely hard

mathematical puzzle within few minutes which makes the model vulnerable.

• 51% attack on proof of work

Proof of work consensus algorithm may suffer from 51% attack, if any node

has the majority of computing power that is more than 50%, it can reverse the

happened transactions; a node with less than 51% is also dangerous.

• Selfish mining

In selfish mining, minors do not reveal the mined blocks into the network; they

broadcast the hidden branch once their requirements got satisfied. As a result

reviled chain is larger than the current public chain, and all minors admit that

longest chain. Before that hidden chain publication, genuine minors wasted their

computational power, and selfish minors were mining without competitors and

got considerable revenue. If all minor joins in the selfish pool then the system will

be vulnerable.

9

Conclusion

IoT has some limitations concerning confidentiality, privacy, and data integrity.

Blockchain is one such technology that provides security by design. So blockchain in

IoT overcomes the existing limitations of IoT because blockchain provides security,

transparency, and availability. However, there are some limitations for a straight-

forward application of blockchain into IoT, because IoT devices are not capable

of running highweight blockchain algorithms and storing huge amounts of data. In

this work, we scrutinize the participation of blockchain in IoT. We also provide an

inclusive survey on BCoT. In this proposed work, we initially present the Internet

of things and blockchain technology. Then, we elaborated on several methods and

techniques which enable blockchain into the IoT domain. We further deliberate all

the challenges and limitations of BCoT.