Blockchain Tech-PoW and PoS — Two Major Consensus Algorithms for Public Blockchains

For the general audience, QuarkChain starts a technical column which will explain the basic knowledge of blockchain technology and decipher the fundamental technical details behind blockchains using layman language. Anyone who has technical questions or feels any “black magic’’ about blockchains can submit the concerns/comments through our bi-weekly AMA (Ask Me Anything), WeChat groups, Telegram, etc. We sincerely welcome any constructive feedback and suggestions in the journey.

Let’s get started with the definition of consensus algorithm. According to Wikipedia, consensus is defined as:

A fundamental problem in distributed computing and multi-agent systems is to achieve overall system reliability in the presence of a number of faulty processes. This often requires processes to agree on some data value that is needed during computation. Examples of applications of consensus include whether to commit a transaction to a database, agreeing on the identity of a leader, state machine replication, and atomic broadcasts. The real world applications include clock synchronization, PageRank, opinion formation, smart power grids, state estimation, control of UAVs (and multiple robots/agents in general), load balancing and others.

In short, consensus can be considered as an efficient way to gain public recognition. There has been a specific case: How can we express emotions to our partners in a proper way?

Currently, the major consensus algorithms in public blockchains are proof of work (PoW), proof of stake (PoS) and its variants (e.g., dPoS).

To put it briefly, hash power is the metric in PoW. For PoS, people with more tokens will have more power to vote. DPoS means that decision-making and election mechanism are added based on PoS where the amount of tokens matters. Just like at shareholders’ meeting, several representatives are elected to make decisions.

Since PoS and DPoS are fundamentally quite similar, we classify them as one kind. Thus, there are two major consensus algorithms currently:

PoW: Power matters.

PoS: Money matters.

In blockchain world, PoW is achieved by a mass of nodes solving the specific problem simultaneously. For example, the result 0.0000000 is required after calculation. In terms of hashpower in blockchain industry, GPU and even specially designed chips are prefered to be adopted due to the higher efficiency than CPU. Many mining machines are no longer operating individually, but they are combined together into a mining pool instead. The mining pool consisting of thousands mining machines is becoming the mainstream these days.

Currently, QuarkChain is super flexible and enable to support multiple VMS, various consensus algorithms and even multi-native tokens in one network to satisfy different requirements of blockchain applications. QuarkChain network consists of two layers of blockchains to avoid 51% attack. We apply shards as the first layer and a root blockchain as the second layer that confirms the blocks from shard layers to ensure the security and scalability.

If you have any questions, please feel free to contact us! We have been holding bi-weekly AMA in telegram community. Welcome to join!

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