Can a blockchain be Centralised? Will it be called as Blockchain if it is centralised?

Question

I was reading lot of articles on blockchain and almost everyone has some different understanding of blockchain.
Is there any accepted definition of Blockchain by any community?

In few articles I read:

• Blockchains are Decentralised while DLTs are not.

• All blockchains are DLT but not all DLTs are blockchain. It added "if transactions get stored in blocks then it is a blockchain else it is not"

From above statements-
Is Decentralisation must for a Blockchain?
Or it is just a Immutable Distributed Database? which can be centralised or decentralised?

Answer 1

I would refer you to the first blockchain application, Bitcoin, which describes the "chain of blocks" in the original Bitcoin Whitepaper.

Blockchain

The term “blockchain” is often overused, that can have different meanings in different contexts. Blockchain technology has 3 major components that together really make it an innovation. Strictly speaking, a blockchain is just a data structure similar to a linked list. Blocks of data reference their previous block by including their digital fingerprint or hash in their block of data. If a previous block is modified, then all the following hashes will be different and it is easy to detect if the data has been tampered with. Even more importantly, is that this establishes an order to when events took place, in the case of Bitcoin, these events are transactions. The final piece is a consensus mechanism that allows participants on a publicly distributed network to all agree on a chain of blocks.

Consensus

A consensus mechanism extends the blockchain data structure by providing rules (agreed to by network participants) that enforce how blocks are accepted by the network as a whole. For example, with the proof-of-work consensus, there is an agreed-upon amount of work that must be done before a block is accepted as valid (its hash must meet a maximum value threshold). The lower the threshold, the more work must have been done (on average) to calculate the block hash. Providing a valid block hash becomes proof of work. This can make it much more difficult to modify past blocks, as the same amount of work must be done in order for the network to accept it as valid, thus distributed consensus can be achieved. This is why “blockchain technology” was invented, to achieve distributed consensus without relying on a third party. “Blockchain technology” is not really that interesting without the proof-of-work component and so it depends on what your definition of “blockchain technology” happens to be.

In conclusion, by this definition of blockchain, it doesn't make sense to use blockchain in a centralized environment (it is for distributed consensus).

Answer 2

One of the best writings on centralization and decentralization is an article by Ethereum creator Vitalik Buterin.

https://medium.com/@VitalikButerin/the-meaning-of-decentralization-a0c92b76a274

In this article he explains how even the most decentralized systems are also centralized to some extent.

Answer 3

Let's firstly make it clear that what is decentralization.

Decentralisation is the process by which the activities of an organization, particularly those regarding planning and decision making, are distributed or delegated away from a central, authoritative location or group. Concepts of decentralization have been applied to group dynamics and management science in private businesses and organizations, political science, law and public administration, economics, money and technology. -- WikiPedia

So basically, there's no central, authoritative person or group or whatever to make decisions or plans in a decentralized system. According to this, I personally would prefer to separate it into two essential levels of a blockchain system.

In terms of the blockchain system(software and hardware) itself, it is decentralized. Because it is based on a distributed computer system, and it also has consensus algorithm (POW, POS, DAG etc.) to make sure each node/party in the system can reach to consistency.

In terms of governance, it can be decentralized or centralized. A typical centralized blockchain system is the private blockchain, since it is governed/managed by a single group or organization. While, obviously, a public blockchain is decentralized on the other hand.

Answer 4

Blockchain is a distributed ledger of Information. The main Concept was taken from the paper of Digital Time Stamping by Stuart Harber. The idea behind blockchain is to remove the centralized System so the decission power is taken from single Entity. Now if you want to make it centralised you are basically doing a trade off of the Basic properties of blockchain.

If you make the blockchain centralised one of the key feature is the consenses where other nodes verify the trnsactions so in centralised System the whole work is done by one node and we can assure that if that node is trustworthy node.

Answer 5

A blockchain can be considered centralized if it is controlled by a single entity or group of entities, rather than being decentralized and distributed among many participants. But it may not be accurate to call it a blockchain in the traditional sense, as the decentralization aspect is a crucial part of the blockchain's design. Without this decentralization, it may be more accurate to call it a distributed ledger technology (DLT) rather than a blockchain.

Answer 6

Block-chain is a distributed, decentralized, public ledger.