Classification of Blockchains

elopio
Mon, 28 Oct 2019 17:13:38 +0000
General

This post is part of our Blockchains Study Group. Take a look there to learn more about related topics.

In the Telegram white paper, they present a very useful classification of blockchains. I think it is a little biased to present their own blockchain as the final step in the evolution of this technology, but it's very useful nevertheless. We will use it as a base to classify the projects we are learning about in our blockchains study group.

As usual, this post is a wiki that will grow over time. Feel free to leave a comment or edit it directly.

This is the criteria we will use to classify blockchains:

Chain architecture: single-blockchain or multi-blockchain.
For multi-blockchain systems:

Types and rules of member blockchains: homogeneous, heterogeneous, mixed.

Presence of a master chain, internal or external.

Support for sharding, static or dynamic.

Interaction between member blockchains, loosely or tightly-coupled.

Consensus mechanism: Proof-of-Stake, Proof-of-Work, or Proof-of-Authority.
For Proof-of-Stake systems:

Consensus algorithm: Byzantine Fault Tolerance, Delegated Proof of Stake, etc.
In particular:

Who can produce or mine a new block?

Are the blocks validated by validator signatures, or are all full nodes expected to validate them?

Is there a designated producer for the next block? Is it known in advance?

Is a newly-created block originally signed only by its producer, or must it collect a majority of validator signatures from the very beginning?

Support for smart contracts: only value transfers, limited scripting, or Turing-complete.

Permissioned or permissionless.

Here are a few examples:

Bitcoin, Litecoin, Monero: single-blockchain, Proof-of-Work, no support for smart contracts.

Ethereum: single-blockchain, Proof-of-Work, with support for smart contracts.

Ethereum 2.0: multi-blockchain with masterchain and sharding, Proof-of-Stake, with support for smart contracts.

Polkdadot: multi-blockchain with masterchain, Proof-of-Stake, with support for smart contracts.

Telegram Open Network: multi-blockchain with master chain, Proof-of-Stake, with support for smart contracts.

In the following months we will be exploring some of these blockchains more in-depth.

Thanks to Nikolai Durov and the Telegram Open Network team for proposing this classification.

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