Harmony CTO Lan Rongjian: Based on FBFT consensus and fragmentation technology to create a real value chain

By extraz | Extraz | 28 Oct 2019

The chain tea interview is a blockchain project report column opened by the chain teahouse. Each week, an interview will be conducted with a project team. The chain teahouse will explore the shining points of different projects and tell the story of the blockchain developer's entrepreneurship. Peer provides the latest project information and industry trends.

BTC and ETH with low TPS are criticized and cannot serve as the public chain of applications that carry a large number of DApps. However, EOS and COSMOS with higher TPS have the disadvantage of being too centralized. Whether the public chain can balance efficiency and decentralization, the Harmony project tells everyone that it is possible to use the already running main network. Harmony is a new generation high-performance public chain based on fragmentation technology, using PoS consensus for nodes. Authenticating, based on the PBFT consensus, self-research and optimize the FBFT consensus, improve the interaction efficiency of the public chain and take into account decentralization.


In this issue of chain tea visit, the chain teahouse invited us to Mr. Lan Rongjian, Harmony CTO in Silicon Valley, USA. He will talk about the entrepreneurial road of Harmony project and explain Harmony's FBFT consensus mechanism and fragmentation solution.

The team's technical members came from the mainstream Internet companies in the United States. In the winter, they insisted on research and development. The main network was launched in June.

Lan Rongjian said that the project was formed in early 18th. The project CEO had previously worked for Google, so many members were from Google. After the CEO's first venture was acquired by Apple, he still wanted to start a business, so he created an offline entrepreneurial party called TGI. Most of the members of the Harmony project met at the party.

TGI is still going on every Saturday and is a very important activity for the company. Many people in the TGI activities have their own views on the blockchain, which touches on the speed and performance of the public chain. The CEO proposes to solve this problem with shards and optimize at the network and system levels. Several early partners hit it off in 2018. Opened Harmony's startup.

Harmony chose to shard because it was a very new technology at the beginning of the year. Most of the team members came from the US Internet giants, and they were very sensitive to technology in the technical departments of Apple and Amazon. The traditional industry segmentation is the way to expand the infrastructure. This is also the future development direction of the blockchain. At that time, there were 5 founding members and 20 full-time employees. The team also has a number of part-time staff, such as community ambassadors, involving about 40 staff members, distributed in many countries, and the project company is located in Silicon Valley, USA.

Harmony is responsible for about 12 people in technology. They are all from Google, Apple, and Microsoft. They are senior engineers. After graduating from the United States, Lan Rongjian stayed at Google and had more than four years of work experience before joining the Harmony project.

At the beginning of this year, Harmony entered the test network stage and experienced three stages of iteration. In June, the first version of the main network was launched. Currently, there are 1000 nodes in the fragment, and 320 nodes are external nodes, which have already produced 4.5 million blocks. The external node is currently involved by the node operator of the community. Lan Rongjian said that this is only a phased setup, and then it will be carried out to a more decentralized main network. The project itself does not control any nodes at all, and is completely run by the verification node.

When talking about the biggest difficulty in the road to entrepreneurship, Lan Rongjian believes that the blockchain winter at the end of last year and the beginning of this year has greatly affected the project funds, and the price of coins has dropped a lot. The external environment continues to deteriorate, fewer and fewer practitioners, and it is difficult to recruit people in the United States. However, in a manner that was not subject to market interference and pragmatic officers, Harmony completed the initial launch of the main network in just one year.

Using PoS for Node Identity Validation Optimizing PBFT Consensus to Create More Efficient FBFT Consensus

351665157-19157aaaad6445fec0728af2e5873bdde8f1be80dc66856b245bcb35dc0feb78.jpeg Harmony is not a project that uses two consensus algorithms. PoS is only responsible for the identification of node identities in the project. Using PoS to verify nodes can effectively prevent witch attacks and prevent non-working nodes from joining the network, rather than acting as a consensus algorithm. The true consensus is still the FBFT consensus evolved from PBFT optimization. The algorithm is more efficient and faster, and can meet more DApp requirements. Each block can output a block every 8 seconds, which can confirm the transaction on the block, user experience. will be better.

The FBFT algorithm does not require a lot of hash values ​​like PoW, and does not require a lot of computational power, and it is better for energy savings. FBFT is a self-study of the team. Optimization is not only the optimization of the consensus process, but also the introduction of the BLS signature mechanism. It can reduce the complexity of the FBFT consensus, improve the efficiency of the consensus, the speed of the block, the capacity of each block, and How many transactions can be processed and delays are reduced.

FBFT is a new algorithm. The verifier does not need to broadcast their votes. It only needs to send the votes to the leader by means of digital signature. The leader synthesizes the received digital signature into a multiple of the data volume O(1). Signing, and then broadcasting, makes the message complexity of the entire consensus process drop from O(n*n) to O(n).

Technology and team are recognized for $18 million in investment Harmony uses fragmentation technology to solve public chain problems   351665157-d24c0d1f4aec54625dfd82f4e74c0781833fb535f7f38ab19785a13022da7eb2.jpeg Currently, the Harmony project has received $18 million in financing through the sale of tokens to Hong Kong-based venture capital firm Lemniscap, Australia's BCA fund, Singapore's UniValues ​​Associates and US's Consensus Capital.

Lan Rongjian said that first of all, these institutions are optimistic about the technical direction and depth of the team, whether it is the optimization of the network layer, the characteristics of the consensus agreement, the new algorithm of cryptography, are very agreeable; the second is to be optimistic about the team, the engineer The background is very experienced, the business team also has Harvard MBA, including Stanford graduate investors; Third, the project CEO has the experience of successful Internet entrepreneurship, this is a social software based on geographical location information, which was eventually acquired by Apple.

At present, many public chains have the disadvantage of low TPS, and the Harmony project is solved by fragmentation technology. The increase in the number of shards can double the efficiency of TPS. The execution cost of FBFT is also relatively low, so the transaction costs are also reduced. If the TPS number is high, it will be difficult to generate network congestion. The cost of not blocking the transaction will not be high. At present, Harmony's transaction fee is one thousandth of ETH.

Another problem that the public chain needs to face is the public chain that uses dozens to one hundred verification nodes like EOS and COSMOS. The average user does not have enough resources and the token becomes a node, and the ecology tends to become too centralized. . Harmony can expand nodes indefinitely, because the number of fragments can be increased by sharding. The more efficient the nodes, the lower the efficiency. However, this is not the case at the slice level. Adding fragments can increase the number of nodes. The more fragments, the more processing power.

At present, there are 1000 nodes in the main network of Harmony, each node has 250 nodes. Based on the characteristics of FBFT consensus, including the improvement of PoS signature efficiency and network layer optimization, the network of 250 nodes is more efficient. The team's goal is to have 400 nodes per shard in the next version of the main network, in order to better ensure the security of the node, and more decentralized.

The same is the use of fragmentation technology to optimize the performance of the public chain, why the Harmony project will progress so much faster than ETH2.0? Lan Rongjian said that the team insisted on the 996 working mechanism in the United States. The start-ups struggled for the same goal, and the direction was clear, so the efficiency was high. ETH 2.0 has no physical company to push, it is the community is doing, although decentralized but the efficiency can not be guaranteed, the more concentrated the staff is more efficient for project development.

As far as technology implementation is concerned, Harmony has a lot of differences with ETH shards. Harmony uses FBFT. ETH uses functions that are not quickly confirmed, and is more prone to bifurcation. Harmony's PoS node verification mechanism will be more efficient, equivalent to the industry's first invention of EPoS, effective equity certification mechanism, can guarantee network security, very fair decentralized Staking mechanism, can make large and ordinary small The household is treated fairly in this mechanism, the system is mortgaged with nodes, the token allocation is very average, and the risk of centralization is reduced.

How does Harmony's random number verification and cross-chip communication work?
  351665157-927a692d83ba3051b31f0a9d19ab50a10f158152d67999d7106f484b30946658.jpeg   The Harmony project chose VRF (verifiable random function) + VDF (verifiable delay function) random number verification mechanism. How do they work? As part of the random number, VRF is a verifiable random person. Each node needs to submit the result of VRF. The Harmony random algorithm is self-developed by the team and is a distributed random number generation algorithm. A random number is not calculated by a node itself. It is generated by a fragment and other nodes. It avoids a node controlling random numbers and makes the result unfair. With the cooperation of VRF and VDF, many nodes work together, and a single node cannot control the results.

VDF guarantees that a single node does not interfere with the final result in the algorithm process. Each node counts the results of the VRF and obtains a unified result through the algorithm. The VRF+VDF random number algorithm will be applied at the Harmony protocol level, including allocating nodes to different shards, ensuring that malicious nodes are randomly assigned to different shards, and the intent of the attack cannot be concentrated to ensure security. In the application layer application, each DApp can use this random number as a random source to make the result fair, and the situation like EOS is not disturbed.

Currently, there are games and stable currency applications on the main Harmony website. The team is also negotiating with more partners, such as game makers and DeFi projects, which are connected to DApp online. Harmony's SDK and developer tools are just getting ready. Currently, DApp is being docked. In the future, there will be more and more applications for the main network. At present, TPS has 1000 per shard and the main network can run 4000 TPS.

The Harmony project also uses efficiency-enhancing technology for cross-chip communication, and the Kademlia routing protocol is used in cross-chip communication. After the Kademlia routing protocol is added, the message propagation between slices and slices does not require too many nodes, only two sharded nodes, and the shortest path node in the middle. The principle of improving efficiency is that sending a message does not require all nodes to hear, but let the two shards and the nodes in the middle shortest path know. At present, Harmony cross-chip communication is very efficient and can be completed in about 10 seconds. Without this technology, all network nodes should be notified, and with this technology, only the nodes on the shortest path are needed.

The recent focus on EpoS's new mortgage mechanism will make Harmony a real-value public chain in the future.
  351665157-026d6a76b077ef0a3dfe7e5dfea39cf1ee92a4bdf5c61f783e17484c90ca9594.jpeg At the end of the interview, Lan Rongjian said that Harmony's plan is to implement EPOS's new mortgage mechanism and launch it on the latest main website. It is the first Staking mechanism in the industry. It has a simple consensus with DPoS and has breakthrough innovation. Decentralization and uniform distribution of wealth bring experience to the blockchain industry and bring fair choices to potential users in the community.

In the long-term planning, Harmony is more optimistic about the application layer, cross-border payment field, and deepen the application of these fields, and truly bring the value of the main network. In the future, the project will continue to dig deeper and explore at the application level. It may develop DeFi, cross-border payment, game applications, or cooperate in various ways, and may receive dividends among them.

Lan Rongjian believes that in the WEB3.0 era, the most important thing in the public chain is basic performance, TPS, time, speed and transaction costs. Harmony has greatly improved at these four points. He believes that Harmony can become truly The public chain of value.

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