Li Ni, global vice president of WanChain, believes that the PoS Ethereum is more democratic and decentralized than the DPoS mechanism. If it proves to have a great advantage over PoW, many new projects may directly adopt the method of Fork to convert to PoS.

"On the other hand, after Ethereum implements PoS, the tps will be greatly improved, which will make some projects turn around from EOS and TRON, and embrace Ethereum again." Li Ni also predicted, but the speed of Ethereum's block production is not necessarily It is as efficient as EOS 21 super nodes.

Yang Zhen, the translator of the Ethereum Yellow Paper, believes that the conversion of the consensus mechanism of Ethereum is equivalent to the expansion of the main network, mainly to solve the tps problem, and it is a bit difficult to do this now:

"If you consider the application scenario, which requires high interaction and processing time, is it necessary to do all the calculation steps on the main network?"

"Before, everyone had a heated debate. For the expansion of the second-tier network, a large number of calculations with transaction requirements should be placed on a separate second-tier network to do this. The process verification can be placed on the main network proof."

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Casper's original design

Discussing any public chain cannot bypass the core concept of consensus algorithm. In 2013, the PoS algorithm was not written into the Ethereum white paper.

"Although the Bitcoin blockchain model is very rudimentary, practice has proved that it is good enough. In the next five years, it will become the cornerstone of more than 200 currencies and protocols around the world."

This is a passage from the Ethereum white paper. Ethereum has adopted the PoW workload proof mechanism of the Bitcoin blockchain from the very beginning.

Bitcoin's Proof of Work is to find a reasonable random number to generate block verification by consuming a lot of computing power.

In Vitalik's view, PoW not only congests "traffic" and wastes energy, but also gradually moves toward centralization.

Because with the increasing difficulty of mining, the application of ASIC professional mining machines emerged, and the emergence of ASIC professional mining machines has resulted in a monopoly of computing power.

PoS - Proof of Stake, is a mechanism for determining the bookkeeping right based on the product of each node's token holdings and holding time. For example, if the product of your principal and time is greater, you will have the priority to bookkeeping. After bookkeeping, the product will be destroyed. This process is called "coin-day destruction".

Compared with the proof of computing power of PoW, the PoS mechanism can effectively reduce energy consumption, shorten the consensus time, and avoid "evil" by the centralized mining pool of computing power.

Although there was a precedent of PPCoin using PoS before Ethereum, the research and implementation of PoS were still immature at that time. A Jian believes that "there are many problems in the operation of PPCoin, such as the 'rational fork' problem (also known as the 'no stake' problem). At that time, Ethereum researchers had not yet found a sufficiently secure PoS mechanism. "

Vitalik Buterin mentioned in the article "Casper's Past, Present, and Future": "Ethereum's proof-of-stake research began in January 2014, starting with the 'Swordsman Protocol'."

Casper (security-deposit based economic consensus protocol) is Ethereum's PoS equity certification protocol. Casper's consensus protocol can constrain the behavior of validators through direct control over the deposit, which is different from the classic PoS proof of stake.

In April 2014, Vlad Zamfir participated in the development of Ethereum as a volunteer. According to Vlad, Vitalik also proposed the concept of "Sword Hand Protocol" with him at the Vienna Bitcoin Summit that year.

"If you sign two agreements at the same time on the fork of the same level, then you will lose the block reward you can get." This is the idea proposed by Vitalik to solve the nothing at stake .

Later, Vlad officially joined the development of Ethereum, and pointed out on the basis of the "Swordsman Protocol" that "let the verifier store the deposit, and the amount is much larger than the reward, so as to drive out bribery attacks."

At the time, Vitalik and Vlad were addressing the problem of bribing attacks (PoS protocols without margin deposits are easily defeated by low-cost bribes).

In early 2015, Vlad met a guy named Matthew Wampler-Doty, and Matthew and Vlad mentioned the concept of margin:

"In the future there will be a Tendermint validator cartel (cartel) holding more than 2/3 of the security deposits, because the remaining validators are not required to build the final block (these 'non-cartel validators verifiers' only hold less than 1/3 of the security deposit). These nodes with less than 1/3 will be blocked and eventually removed from the validator list. A new set of nodes holding more than 2/3 ( A security deposit cartel will then be created, and this process will continue until only (at most) two validators remain.”

Vlad was enlightened and began to study "Cartel Verification", and added this concept to the "Swordsman Agreement", which is the original design of Casper: Swordsman Agreement + Security Deposit.

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Moving towards a PoS mechanism

Ethereum currently has two development teams, one is responsible for the development and maintenance of the current Ethereum (Ethereum 1.x version), and the other is responsible for the development of Ethereum 2.0. The Constantinople fork stays within the scope of Ethereum 1.x version upgrades.

Ethereum 2.0 is relative to the current stage of Ethereum. 2.0 will start from the Serenity plan and move towards the PoS equity certification mechanism.

In the Casper PoS mechanism mentioned in the above article, Casper will adopt two versions: Vitalik Buterin's version of Casper FFG hybrid proof and Vlad Zamfir's version of pure equity proof Casper CBC.

According to James Prestwich, author of "ETH 2.0 Engineering Guide", the Ethereum 2.0 test network is expected to be launched in the first quarter of this year.

In the early days of Ethereum 2.0, the Casper FFG mechanism was used to run and generate blocks. At that time, the beacon chain (beacon chain) will be a mirror image relationship with Ethereum 1.x. The beacon chain is a side chain, but it does not have any functions. Ethereum 1.x is the main chain. According to the original PoW mechanism Block out.

A Jian, editor of EthFans, told Odaily: "Users can obtain the validator qualification to participate in the beacon chain by locking the ether currency into the relevant contract on the PoW chain, and get PoS rewards, but the new ether currency on the beacon chain cannot be returned. to the PoW main chain."

In the beacon chain sharding phase, the beacon chain will generate 1024 shards, each with an address. The Casper FFG beacon chain uses a second random election to complete block verification and prevent verifiers from doing evil.

The verifier needs to put 32 new ethers into the shard address as a deposit. The beacon chain randomly selects 128 verifiers as pending committee members every 64 blocks (10 blocks per minute), and then the beacon chain randomly selects a certain number of committee members from the 128 pending committee members to form a committee.

The selected committee members can perform verification on their respective blocks to generate new blocks, but the "serving" period of the committee members is only 6.4 minutes, and the block controller after 6.4 minutes will be born in the next new committee.

Although Ethereum's PoS proof of rights is essentially an off-chain governance, technical means are used to strengthen on-chain governance in terms of details.

Yang Zhen, the translator of the Ethereum Yellow Paper, believes that compared with DPoS share authorization certificate, Ethereum’s PoS wants to make a more equal voting method, which is very different from EOS. “I believe in one sentence, human nature cannot stand Tested."

However, the Constantinople upgrade originally scheduled for January 16 has nothing to do with Casper FFG and Casper CBC.

It is worth noting that among the five EIP upgrade protocols in Constantinople, EIP-1234 is the established strategy of "boiling a frog in warm water" during the conversion process of Ethereum to the PoS mechanism.

Proposed by Afri Schoedon on July 19, 2018, the agreement proposes to delay the difficulty bomb for 12 months and reduce miner rewards from 3 ETH to 2 ETH.

The proposal was passed at the Ethereum developer video conference on August 31 last year and was implemented when the Ethereum Constantinople hard fork.

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The architecture diagram of Ethereum 2.0 is from Hsiao-Wei Wang

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text

From 2015 to 2016, Vitalik and Vlad's research on PoS was still in the exploratory stage, and the "fisherman's dilemma" and "betting consensus" problems in scalability research took most of the Ethereum development team's time.

Vitalik later concluded: "We suffered a series of failures in solving some core problems in PoS, scalability, and Vlad quietly suspended all his work in Casper CBC."

The DAO incident and the DoS attack made the Ethereum team almost have no time to take care of the previous research direction for as long as 6 months.

Until 2017, Vitalik and Vlad's Casper research turned a corner. First, Ethereum developed a protocol called minimum slashing: once a block is approved by 2/3 of the verifiers in a certain round, the parent block of the block will be finalized. The minimum slashing condition is the core idea of ​​Casper FGG.

FFG is a PoW+PoS hybrid consensus mechanism in the transitional stage of Ethereum. In FFG's original design, Vitalik superimposed a proof-of-stake protocol on Ethereum's proof-of-work protocol, that is, blocks will still be dug through proof-of-work, but there will be a proof-of-stake check every 50 blocks. Points (PoS blocks) to evaluate finality.

Vitalik excitedly said: "This will be a mechanism that allows us to quickly move to a hybrid consensus with minimal impact on existing blockchains, and then theoretically we will be able to upgrade to full proof-of-stake."

To this end, the Ethereum development team also made a Python test client, using different VPS, servers and computer communications for testing.

Vlad also published a paper on Casper CBC in 2017. Unlike FFG, CBC emphasizes"build fixes", the protocol states:

In the CBC protocol, there is a predictive security oracle machine. When setting an exception to a reasonable estimate of errors, it lists all errors that may occur in the future. Within a given interval, its correctness is determined by its construction process. ensure. CBC is a pure PoS proof of stake and is expected to be implemented in Ethereum 3.0.

The delayed "bomb difficulty" was also proposed at this time. On June 21, 2017, the EIP-649 protocol proposed to delay the difficulty of the bomb in the upgrade of Constantinople, reducing the average block time to less than 15 seconds, and at the same time reducing the block reward from 5 ETH to 3 ETH, which is Ethereum's Transitions buy time.

In 2018, several Ethereum development teams have attempted to implement sharding technology. According to Vitalik:

“On the sharding side, it’s finally becoming clear that having the core of the sharding system on the PoS chain gives us greater efficiency.”

"Becoming a contract on the PoW chain, we have to deal with the overhead of the EVM, the Gas mechanism, and the unpredictable PoW block time; PoS + sharding can bring a series of benefits such as faster block time. "

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ongoing controversy

The penultimate line of Vitalik's personal blog profile reads: Religion: crypt.

As early as 2014, Vitalik said: "Proof of stake is still one of the most controversial discussions in the field of cryptocurrency." Today, different people still have different views on the issue of consensus mechanisms.

"The loss of energy is reduced, and it no longer needs to be mined. In theory, PoS will greatly reduce the risk of centralization." Li Ni believes that PoS is much more advanced than PoW.

Liu Jie, the person in charge of Kuangbao, believes that there is nothing wrong with PoW. Many people think it is a waste of electricity. My understanding is the opposite: "The miners' electricity bills actually rely on the role of the economy to improve the security of PoW digital assets. So big assets, so much electricity bills are needed to maintain its safety and operation.”

The PoW mechanism has created an oligopoly, while PoS is a game for capitalists. The poor get poorer, and the rich keep getting rich. Even if Ethereum gets rid of the oligopoly, it will inevitably fall into the gap of the rich getting rich again. Regardless of on-chain governance or off-chain governance, the rules and procedures of the consensus mechanism are formulated by humans.

The issue of the consensus mechanism has been debated endlessly in the industry. If it rises to the level of human social governance, it is nothing more than how well you manage it, or how little you manage it. Under the premise of certain security, weak centralized management will inevitably bring about efficiency problems.

Gu Ya, the founder of The Force, told Odaily: "Currently, no matter DPoS or PoS, from a security point of view, neither PoW is perfect. The only imperfection of PoW is that it is too decentralized, the community governance is not good, and the promotion is very slow. But there is no way, security and decentralization are either-or issues, for example, when our team is working, it is called PoW, and when it is in a meeting, it is called PoS, because the CEO has the final say.”

"The only problem with PoS is that it hasn't been made yet. (PoW) Ethereum has been calling for PoS for a year or two, but it hasn't been made, and there is nothing wrong with the code. Hasn't anything been changed in this one-fork upgrade? No? Adjusted a few bugs, and then optimized a few data."

On the evening of January 18, the Ethereum development team once again postponed the Constantinople upgrade event to February 27 at 16:56, with a block height of 7,280,000, regarding the EIP-1283 protocol vulnerability in a conference call.

If Ethereum is successfully upgraded, how much time can the difficulty bomb issue be left for the Ethereum development team before the tranquility comes?

A Jian believes: "It's hard to say, maybe in the middle of the year, maybe at the end of the year. There are really many problems that need to be solved in this process. First, determine the fork selection rules on the beacon chain, and then realize the pledge contract on the PoW chain. "

If Ethereum evolves to 2.0, the final problem to be solved is nothing more than three points:

(1) Realize a robust PoS consensus mechanism;

(2) Fragmentation;

(3) Convert EVM to EWASM.

To sum it up is simple: a decentralized smart contract platform that can operate stably and efficiently. Good or bad, let's make one first.

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The author, Wu Yan, focuses on mining and blockchain reports. You can add WeChat BIG-BYE for communication. Please note your position and reason