Recently, Zhang Zhenfeng’s team from the Institute of Software, Chinese Academy of Sciences, and Tang Qiang’s team from the New Jersey Institute of Technology, made an important breakthrough in the Byzantine Fault Tolerance (BFT) consensus research on the core technology of blockchain, and proposed the first fully practical asynchronous consensus algorithm in the world. Dumbo Byzantine Fault Tolerance (Dumbo BFT) algorithm” (referred to as “Dumbo BFT algorithm”).
Why is the consensus algorithm important in the blockchain technology with “decentralization” as the main feature? What is “Byzantine fault-tolerant consensus algorithm”? What are the advantages of “Dumbo Algorithm”?
Why is consensus algorithm important?
“Decentralization” is one of the characteristics of blockchain. In a decentralized system, there is no role responsible for the “decision board”, which is like a temporary tour group. Some people want to go east and some want to go west.
To give another example that is closer to life, in the traditional financial system, A transfers a sum of money to B. This behavior will be stored in the bank database. The authenticity of transaction data is guaranteed by traditional institutions such as banks. The record shall prevail.
But in a “decentralized” blockchain system like Bitcoin, some nodes may record the transfer of funds from A to B, and some nodes have no records. Is there such a thing as a transfer? Whose record shall prevail?
Obviously, in the above two cases, it is very important for the entire system to make a unified decision through a suitable consensus mechanism.
Therefore, in the world of blockchain, different nodes finally achieve data consistency through the preset consensus algorithm. This is actually a general rule. As long as everyone participates in the operation according to this rule, the result can be obtained by others. Recognized.
What is the relationship between “Byzantine fault-tolerant consensus algorithm” and Byzantium?
In actual operation, the consensus algorithm is not flawless. Challenges from all parties often affect the achievement of consensus, and the biggest challenge still stems from the “trust issue.”
In 1982, the Turing Prize winner Leslie Lamport and others put forward in the paper such a hypothesis that might make the consensus algorithm fail, that is, the “Byzantine Generals Problem”.
What is the “Byzantine Generals Problem”?
It can be seen that the Byzantine Fault Tolerance (BFT) consensus algorithm is a consensus algorithm derived from the Byzantine Generals Problem. Its purpose is to solve how to reach a consensus in a non-trust environment.
Similar stories are more common in the history of China, such as the “Combined Vertical and Horizontal Links” in the Warring States Period: Qin’s power continued to grow stronger and became a common threat to the other six countries, so the six countries “joined vertical” and joined forces to resist the strong Qin. . At the same time, the State of Qin also joined the alliance with the six countries separately through “Lianheng”, with the aim of destroying the “integration” between the six countries, so as to isolate the countries and defeat them individually.
In the above context, both Qin and the other six countries are faced with the so-called “Byzantine generals problem”-they must fight together and prevent themselves from being destroyed. At that time, the ancients often used hostages or marriages to build trust. In the context of blockchain, similar problems can be solved by the “Byzantine fault-tolerant consensus algorithm”.
Therefore, as the key core technology of the blockchain, the “Byzantine Fault Tolerant Consensus Algorithm” is a core algorithm that ensures the safe and reliable operation of the blockchain, and improves the scalability and performance of the blockchain. It has high operating performance, low resource consumption, and easy deployment. Such characteristics are favored by the industry and are widely used in Chinese and foreign blockchain systems.
What’s so special about Dumbo Algorithm?
Researcher Zhang Zhenfeng, who mainly completed the research results, said in an interview that how to design an efficient asynchronous “Byzantine fault-tolerant consensus algorithm” is a well-known problem in the field of cryptography and distributed computing. Since the 1980s, many internationally renowned scholars, including many Turing Prize winners, have explored this problem. The “Honey Badger BFT” proposed in 2016 is the first approach to practical use. The asynchronous consensus algorithm has been applied to the blockchain platform.
Zhang Zhenfeng pointed out that in order to design a fully practical asynchronous consensus algorithm, the Institute of Software of the Chinese Academy of Sciences launched the “Dumbo Algorithm” research work in 2015. This algorithm analyzes the “Honey Badger Algorithm” from a unique perspective and reveals the root cause of its performance limitations. The increase in running time caused by a large number of randomized sub-module calls, a new provable and reliable broadcast primitive is proposed, the correct completion of transaction broadcast is guaranteed through cryptographic “proof”, and an efficient construction method based on threshold digital signature technology is given. An innovative multi-value Byzantine consensus application that converts the consensus on transactions into a consensus on “proof”, enabling the “Dumbo Algorithm” to tolerate 1/3 of malicious nodes while breaking through the performance of asynchronous consensus algorithms Design challenges.
At present, in a test network of 100 consensus nodes spread over four continents around the world, the confirmation delay time of the “Dumbo Algorithm” is 24 seconds, which is less than 1/20 of the “Honey Badger Algorithm”, and the transaction throughput is nearly 18,000 pens, which is more than 9 times the “honey badger algorithm”.
Zhang Zhenfeng also said that the joint team completed the creative breakthrough of the “Dumbo Algorithm”, which not only solved the theoretical problem of asynchronous consensus algorithm design, but also greatly improved the performance and surpassed the current “honey badger algorithm” adopted by the industry. The world’s first fully practical asynchronous consensus algorithm. This research result can provide a new generation of core technology with strong security, high performance and scalability for the construction of China’s blockchain infrastructure.
Author/ Translator: Jamie Kim
Bio: Jamie Kim is a technology journalist. Raised in Hong Kong and always vocal at heart. She aims to share her expertise with the readers at blockreview.net. Kim is a Bitcoin maximalist who believes with unwavering conviction that Bitcoin is the only cryptocurrency – in fact, currency – worth caring about.