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Blockchain Technology

a copy of the blockchain state. Thus, if an adversary could alter the data in any of

the nodes, the altered state of blockchain would be automatically rejected, and an

alteration would not be possible.

With a distributed architecture, blockchain also ensures the availability of data.

Unavailability of some nodes does not disrupt, as replicated data is available in the

blockchain environment. Smart contracting can enable a secure way of sharing

data with secure authentication and authorization. A predefined set of rules can be

defined to ensure that data sharing is secure. “Hyperledger Fabric” is a particular

kind of blockchain. It uses a unique execute-order-validate architecture.

4.9  CHALLENGES IN IMPLEMENTING BLOCKCHAIN WITH IoT

Blockchain development was not focused on solving IoT’s security challenges, and

similarly, IoT has multiple limitations to supporting the blockchain-based implemen­

tations. Some of the key challenges are:

Resource limitation: Blockchain is not based on a resource-constrained envi­

ronment; thus, any solution based on the blockchain must consider the IoT

environment’s resource constraints. Energy and resource requirement to

support multicast and broadcasts, exchange of keys and certificates may

not be suitable for the current IoT architecture. The resource and energy

required to support the blockchain operations need to be addressed in IoT.

Heterogeneous devices: The IoT ecosystem with multiple layers has a wide

range of systems, including low-power sensors to high-end servers, and is

supported by heterogeneous technologies. Blockchain solutions thus need

to be technologically conducive to be scalable and popular.

Interoperability of security protocols: IoT has different security require­

ments at different layers; however, solutions to these must work together

to ensure complete security. Thus, a scalable solution can be found if it has

wide adaptability.

Trusted updates and management: IoT devices are distributed and can num­

ber in the thousands; this poses a severe challenge for updating and trust

management. This challenge is one of the open areas for research.

Blockchain vulnerabilities: Blockchains also have known and unknown vul­

nerabilities (Li et al. 2018). Adversaries may compromise a miner’s hashing

power. Also, there can only be limited randomness of the private keys.

Physical vulnerabilities: IoT devices are mostly located in vulnerable loca­

tions; moreover, they are built with cost-effective, easy to assemble physical

parts. This poses an opportunity for adversaries to gain access physically

and exploit the underlying layers. Adversaries with physical access may

render the security offered by blockchain ineffective.

Lack of IoT-centric consensus protocol: Blockchain consensus protocols

are not built specifically for the IoT environment. The absence of a proper

consensus protocol may delay the confirmation of the transactions. IoTs

are time-sensitive and may not be tolerant of the time delays the current

consensus protocols produce.