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Consensus Mechanism Used in Shardeum

Consensus Mechanism Used in Shardeum


Shardeum is a new layer 1 blockchain network that will go live after its mainnet launch in Q4 of 2022 as per its litepaper. It uses a novel combination of Proof of Stake (PoS) + Proof of Quorum (PoQ) consensus mechanism.

Proof of Stake ensures that anyone with the minimum required stake can participate in validation. Proof of Quorum determines how the transactions are validated within a consensus group.

The term ‘consensus’ generally refers to an agreement reached between a group of individuals or between different groups. Think of a gathering of individuals picking a movie to watch. A consensus is reached if there is no dispute on the suggested movie selection. The group must have the ability to determine which movie to watch if there is a disagreement. 

Consensus mechanisms are a vital part of any blockchain network. Without a consensus mechanism in blockchain, it would be impossible to maintain a distributed ledger of transaction data and ensure that all nodes on the network agree on the current state of the blockchain. The complete set of protocols, incentives, and concepts that enables a network of nodes to concur on the state of a blockchain is referred to as a consensus mechanism.

There are a variety of different consensus mechanisms that have been developed, each with its own advantages and disadvantages. Bitcoin uses a proof-of-work (PoW) based consensus mechanism, while Ethereum uses a proof-of-stake (PoS) based consensus mechanism. Shardeum, meanwhile, will be using a combination of the proof-of-stake and proof-of-quorum consensus mechanisms. How will that work? Let’s find out!

POQ Compliments Dynamic State Sharding

Shardeum’s consensus is designed to increase TPS linearly with each node joining the network. This is of significance since Shardeum will be a dynamically state sharded network. ‘State’ is considered the latest record of information of the account balances and smart contracts on a network at any given time.

In typical blockchain networks, the state of the network does not change until a majority of the nodes agree on the current state of the chain. Thus, the computing power of unsharded networks is as good as the node with the lowest processing power. However, dynamic state sharding enables Shardeum processes transactions simultaneously across shards and maintain atomic/cross-shard composability through transaction-level consensus. Further, on typical 1st and 2nd generation blockchain networks, transactions at best, are processed sequentially and at a block level which slows down the network significantly. On Shardeum though, transactions are processed simultaneously across multiple shards or partitions.

What is Proof of Quorum (POQ)?

As opposed to other consensus algorithms in use today, nodes in PoQ validate the transactions individually as soon as they are received with a time stamp (with no possibility of double spends). This is followed by gossiping the transactions to all the other nodes in a consensus group/shard on the network instead of every node on the network. Every node, essentially, will know that every other node in the group knows about a particular transaction. This enables a trustless and leaderless collection of electronic votes (or quorum) in the form of receipts.

E-voting enables consensus nodes to digitally sign transactions without the need to ‘send’ votes preventing forgery. And when there are more than 50% of the receipts (quorum), transactions are committed on the network. Along with its unique gossip protocol, the consensus algorithm used on Shardeum will also auto-rotate the validator nodes on the network, making it extremely difficult for bad actors to attack the network.

Further, processing individual transactions at transaction level instead of block level eliminates limitations of a fixed block time and block size as is the case on typical blockchains. Since Shardeum is a dynamically state sharded network, auto-rotation of validator nodes and transaction level consensus are critical. One, it increases security, as mentioned above. Two, unlike static state sharding deployed by more recent networks, Shardeum doesn’t have to “wait” for new nodes to join the network and create a shard to parallelize the processing of transactions. Thereby, finality is reached very quickly with low latency which helps to avoid network congestion. It would also mean the network won’t need excessive energy more than what is required to process transactions.

A Fast Internet Connection is Enough to Increase TPS

The processed individual transactions are grouped into blocks or partitions and passed on to archive nodes. This allows the consensus nodes to not have to deal with storing the transaction history and only maintain the current state of the accounts they handle. That means a fast internet connection alone could be enough for validator nodes (or validators) on the network to significantly increase its throughput at any given time.

According to the chief scientist of Shardus (the protocol layer of Shardeum), Omar Syed – once you’ve done the consensus for the transactions, the data structure you use to store them does not matter. The reason why it matters for other networks is because the data structure is tightly coupled with the consensus.

Staking is an essential component in the validation process of Shardeum to discourage and slash bad actors. Thus, PoS + PoQ will render the Shardeum highly scalable and secure while the fee on the network remains low and stable and it will be virtually impossible for a malicious node to take over the network at any given point in time.


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A consensus mechanism in blockchain is important in ensuring the integrity of the blockchain and ensuring that all transactions are valid. However, there is no one-size-fits-all consensus mechanism, and the most appropriate mechanism for a given ledger depends on factors such as the desired level of security, scalability, and decentralization.

Through its usage of the proof-of-stake (PoS) and proof-of-quorum (PoQ) consensus mechanisms, Shardeum aims to use dynamic state sharding to increase linear scalability and transaction capacity while also maintaining high levels of security and low fees. 

We hope this post has helped you learn in detail about dynamic state sharding and the proof-of-quorum (PoQ) consensus mechanism used by Shardeum.

Frequently Asked Questions (FAQs)

1. What is Blockchain Consensus?

The consensus mechanism is the heart of a blockchain. It allows the network of nodes to agree on the current state of the blockchain, ensuring that the ecosystem is coordinated and functioning properly. There are a variety of consensus mechanisms, each with its own advantages and disadvantages. Without a consensus mechanism, there would be no way for the network of nodes to agree on the current state of a decentralized blockchain network.

2. How many Types of Consensus are there?

Different consensus mechanisms can be used in blockchain according to its use case, and there is no set number of consensus mechanisms that can be created. The most common consensus mechanisms include proof-of-work (PoW) and proof-of-stake (PoS). PoW is used in Bitcoin, while PoS is used by Ethereum. 

3. What are the Elements of Consensus?

A consensus mechanism in blockchain includes certain elements like reaching an understanding, collaboration, cooperation, giving each node equal rights, and requiring each node to take part in the consensus process. With these elements, a consensus mechanism seeks to achieve a shared understanding and agreement that benefits the whole blockchain network.

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Opinions expressed in this publication are those of the author(s). They do not necessarily purport to reflect the opinions or views of Shardeum foundation.

About the Author : Shriraam Sekar is a crypto writer/marketer involved in the space since 2019. He covers Layer 1s, DeFi, NFTs, Metaverse, GameFi, SocialFi, and crypto regulations. Follow him on Twitter for collaboration related to crypto/Web 3.0

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