The optimization of consensus algorithms as a grip to improve the operational efficiency and scalability of blockchain systems has become an important direction of concern for industry and academia.
As an efficient consensus mechanism is crucial for the whole blockchain system, fractional-based ANFS’s original Hybrid Proof of Sequence (HPOS), which integrates Proof of History(POH), Nominative Proof of Interest (NPOS), and Practical Byzantine (PBFT), and uses Verifiable Random Function (VRF) to select committee nodes and achieve consensus eventually, was recently unveiled. In HPOS, a consensus committee composed of multiple nodes completes transaction collection, transaction timing verification, block construction and final state confirmation of the blockchain, and adopts the NPOS mechanism as the incentive mechanism of the consensus committee.
“Since the birth of Bitcoin, its underlying support technology, blockchain, has received widespread attention. Up to now, blockchain has been widely used in many fields such as finance, Internet of Things, and product traceability, while as a new type of Internet infrastructure, the application scenarios and application modes of blockchain have also shown a rapid update. However, in the process of further promoting the application scenarios of blockchain technology to the ground, the shortcomings of blockchain technology in terms of operational efficiency and scalability are also increasingly highlighted”, said a developer.
Hybrid Proof of Sequence, which is based on sharded technology and incorporates the core idea of POH consensus mechanism. Unlike the traditional POH consensus mechanism, the HPOS mechanism is based on the sharded technology, in which the network transactions are randomly assigned to multiple shards, and each shard is constructed by the shard consensus node selected by the VRF function to generate the transaction sequence of the shard, and any node within the shard can verify the shard by computing any fragment of the transaction sequence of the shard. Among them, the consensus nodes of each shard jointly form the network-wide consensus committee. To prevent collusion, the nodes in the consensus committee will be updated every certain time, and the NPOS mechanism is used to realize the incentive for the consensus committee nodes”, he added.
In the HPOS consensus mechanism, the participating nodes are divided into general user nodes, shard sequence generation nodes, and shard sequence verification nodes. General user node GU (General User). In the HPOS consensus algorithm, GUs do not participate in consensus directly, but are randomly assigned to different shards and can be informed of the latest status of the whole system through the P2P network. SG (Sequence Generator) is responsible for sorting the transactions in its shard, constructing the sequence of transactions in its shard, broadcasting the sequence of transactions in its shard within the shard using the Gossip protocol, and maintaining communication with SGs in other shard using the Kademlia protocol. A Sequence Verifier (SV) node is responsible for verifying the transaction sequences generated by the SG and broadcasting the results within the shard. In general, the SV has the same arithmetic power as the SG and can replace it in case of SG failure.
“The HPOS consensus has certain hardware requirements for SG and SV, so at the beginning of the nodes entering the system, they need to prove their hardware performance, and the proof mechanism is like POW, where the first 11k nodes among n nodes will be selected. After that, by running the NPOS protocol, the top k nodes with the most votes among the 11k candidate nodes will form the consensus committee of the whole network, and the next 10k nodes will form the supervisory committee of the whole network. With the help of VRF, each SG node and every 10 SV nodes will be randomly assigned to each shard. This approach can effectively avoid the collision caused by fixing SGs and SVs in one shard”, the developer maintained.
According to the developer, each SV node in the shard will verify the generated shard transaction sequences in parallel, i.e., each SV node will be responsible for verifying 1/10 of the shard transaction sequences. Therefore, the verification speed of the shard transaction sequence will be ten times faster than its generation speed in general. When each SV in the shard completes the verification of the shard transaction sequence fragment it is responsible for, it will send the verification result with its own signature, and when all the verification results of all SVs in the shard are collected, it will release the shard transaction sequence and encapsulate the sequence into the block, and then announce the latest status of its shard blockchain to the whole network.
Under the consensus of HPOS protocol, each shard maintains a unique shard transaction sequence, but no longer sets a unique transaction sequence for the whole network, i.e., the transaction sequence of the whole network is just a concatenation of the transaction sequences of each shard, and the transaction sequences are not sorted among the shard, the developer informed the press.
About the Company
Hybrid Proof of Sequence (HPOS) is a high-performance blockchain consensus algorithm from ANFS.
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