To understand the spectrum of blockchains, I will do a quick refresher on what a blockchain is. A blockchain is an immutable database distributed across many nodes (computers). The block part of the word blockchain refers to the data or state that is stored. The chain part refers to how the blocks are stored or chained to each other cryptographically.
When we first learn about blockchain, we often only hear about public blockchains such as Ethereum and Bitcoin. Public blockchains are a resourceful type of blockchain and probably the most used, but they are not the entire story.
The reality is blockchains fall on a spectrum. Each type of blockchain has a specific use case that makes it a better choice from publicly accessed projects to private projects or enterprise networks. As more companies look to secure or optimize their processes, I predict some blockchain and other Distributed Ledger Technologies will emerge in more privatized settings.
There are some features we have to consider when we want to distinguish each type of blockchain from each other:
Access: Who has access to the blockchain and who is it for?
Participants: Who are the participants of the blockchain network? Who can read and write to the network?
Security: What sort of consensus mechanisms does it use? How is this network secured?
A consensus mechanism is a process that ensures that at least 51% of the blockchain nodes (computers) agree on the state of the blockchain.
There are four main types of blockchains: public, private, consortium, and hybrid:
Access: Anyone is allowed to join and access a public blockchain.
Participants: Participants on a public blockchain are considered pseudonymous and permissionless. Any node can read or write to a public blockchain network.
Security: Public blockchains are usually secured via consensus mechanisms such as Proof of Work or Proof of Stake. Because of the number of nodes, public blockchains are considered very secure.
Advantages: Fully decentralized. Transparent and not controlled by a single entity.
Disadvantages: Not recommended for storing sensitive data.
Examples: Bitcoin, Ethereum, Litecoin
Access: Only single organizations have access to their private blockchain.
Participants: Only certain known nodes have access to read and write to this network.
Security: Private blockchains are usually secured via voting or multi-party consensus.
Advantages: Great for storing sensitive data pertinent to an organization.
Disadvantages: Partially decentralized. Harder to secure with fewer nodes.
Examples: Ripple
Access: Multiple organizations have access to a consortium blockchain.
Participants: Similar to private blockchains, only certain nodes have read and write permission on this blockchain.
Security: This network is secured via pre-approved participants and multi-party consensus.
Advantages: Great for working collaboratively among multiple organizations.
Disadvantages: More decentralized than private blockchains, but still not fully decentralized.
Examples: CargoSmart, Hyperledger, Quorum, Corda
Access: Multiple organizations can access a hybrid blockchain.
Participants: Only selected participants are allowed to update the blockchain. Some policies allow for participants to read the blockchain.
Security: Only permissioned participants are allowed to update this blockchain. Hybrid blockchains are considered more secure than private blockchains but less than public due to the number of nodes.
Advantages: Having participants read but not write to the network increases transparency while maintaining control over the database.
Disadvantages: More decentralized than private blockchains, but still not fully decentralized.
Examples: IBM Food Trust,
Frankenfield, J. (2021, September 21). Consensus mechanism (cryptocurrency). Investopedia. Retrieved October 14, 2021, from https://www.investopedia.com/terms/c/consensus-mechanism-cryptocurrency.asp.
Public vs private blockchain: How do they differ? 101 Blockchains. (2021, September 19). Retrieved October 14, 2021, from https://101blockchains.com/public-vs-private-blockchain/.
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