The Impossible Triangle of Blockchain: Decentralization, Security, and High Performance

In the distributed field, there is a famous CAP theorem: distributed systems cannot ensure consistency, availability, and partition tolerance at the same time, and the design needs to weaken the demand for a certain feature.

The CAP principle states that a distributed system can only guarantee at most two of the three properties.

Blockchain is essentially a decentralized distributed ledger database, and it also has the "impossible triangle". Today, let's talk about how the "impossible triangle" is balanced and compromised in the blockchain world.

The “Impossible Triangle” in Blockchain

Decentralization, security, and high performance constitute the " impossible triangle " of blockchain. In the design, it is impossible to achieve all three characteristics at the same time, only two of them can be met.

Decentralization means having a large number of nodes participating in block production and verification. Generally, the more nodes there are, the higher the degree of decentralization.

Security is the cost of gaining control of the network, and is usually anchored to real-world assets in the design of the consensus mechanism. For example, the proof-of-work mechanism (PoW) is anchored to computing power.

Transaction performance is the number of transactions processed per second (TPS). The main reason for the low performance of blockchain is that each transaction must be agreed upon by all nodes.

How do mainstream projects compromise in the face of the “impossible triangle”?

Mainstream blockchains Bitcoin, Ethereum, and EOS have all compromised on some feature of the "impossible triangle".

As a decentralized digital currency, Bitcoin sacrifices performance characteristics to meet the design requirements of decentralization and security. Currently, the cost of attacking Bitcoin is the highest among all PoW public chains. With the upgrading of ASIC mining machines and the continuous addition of new mining machines, the computing power of the entire network can be continuously improved.

Ethereum 2.0 will adopt the Proof of Stake (PoS) consensus mechanism. On the Ethereum network, not only can transfers be made, but also smart contracts can be run, and the application scenarios are more complex. However, Ethereum currently has low performance and is more prone to congestion.

As a blockchain application platform, EOS is often accused of being centralized. EOS uses the Proxy Proof of Stake (DPoS) consensus mechanism, with 21 super nodes responsible for bookkeeping and block generation. Due to the small number of nodes, it is most likely to be questioned by the outside world in terms of "decentralization" among the three major public chains.

summary

In fact, the "impossible triangle" of blockchain is not a conclusion reached through rigorous demonstration, it is just a summary of the actual operating conditions of various public chains.

I hope that with the advancement of blockchain technology, the "impossible triangle" can become possible.