Why is it said that the ETH PoW fork is not technically orthodox?

Original title: "Why ETH PoW forks are not orthodox from a technical point of view"

Original author: @0xTodd, Partner, Nothing Research  

I see that many friends often confuse various "forks" and why ETH PoW is unorthodox from the perspective of forks. I want to popularize a little concept today.

Blockchain, as the name suggests, is a chain of many blocks. New blocks, never stop receiving old blocks. If we say that our real world calculates time in seconds, the world on the blockchain calculates time in blocks as the smallest unit.

There are two kinds of forks in the world:

1. Forks caused by out-of-sync networks.

2. Forks caused by differences in versions.

Let’s talk about the first type first, the fork caused by network problems. This is a very common phenomenon that happens every day. For example, when two miners solve the problem almost at the same time and package a new block, whose block is eligible to receive the old block? Bifurcations occur naturally.

Generally speaking, miners will think that the first calculated block is a legal block. However, I am afraid that the two miners will calculate it almost at the same time, such as a difference of a few milliseconds, and then count the delay of broadcasting in the network. Then naturally, it became two groups. Someone received block A first, and someone received block B first.

  At the same time receive the new area Block

In order to solve this problem, the industry has the "longest chain principle". It stipulates that if the blockchain is bifurcated at a certain height, the block whose chain is longer will be meaningful, and the shorter one will be discarded.

As shown in the figure, starting from the height of the fork, two miner groups start to compete in computing power, and all other miners have to choose sides. Because the hash is calculated violently, the party with the stronger computing power can usually calculate it faster. But in theory, there is also a weak side who is lucky enough to overtake.

  Computing Competition< /blockquote>

The winner earns all block header rewards + handling fees, and the loser gets nothing, wasting electricity in vain.

Of course, ETH specially designed uncle blocks in order to solve this problem. Uncle is father's younger brother, but uncle has no son. It allows losers to get a little compensation, which can prevent some miners from dying.

If one party is malicious, it is a 51% attack. If neither party is malicious, it is a normal fork. This is also the reason why when the exchange requires tokens to be recharged, they have to wait for several blocks before they are credited.

Then, as shown in the figure, the longest chain becomes the main chain, and the storm of network forks is over.

  the winner becomes Orthodox main chain

Then let’s talk about the second type, what is the reason A fork caused by a divergence of versions.

In theory, ETH has been forked many, many, many times, most of which are due to system version upgrades. For all forks caused by version upgrades, the longest chain principle [does not] apply. The longest chain principle is only applicable to solving network synchronization problems.

This will be further divided into hard forks and soft forks.

For the hard fork caused by the upgrade, if the whole network agrees, no new fork chain will be born. It is actually a complete replacement of the old chain by the new chain. The representative case is the "London upgrade" of Ethereum. It is called an upgrade, but it is actually a London fork. The London upgrade brought EIP-1559 (fee burn) and no new chains were spawned. This is like, the Qing Dynasty basically inherited the territory of the Ming Dynasty, and the Republic of China inherited the territory of the Qing Dynasty.

  EIP1559 is standard Hard Fork Upgrade

But , if the community does not reach a consensus on version upgrades, it will cause splits. For example, ETC forks, and the two chains of ETC and ETH are completely separated. The former is the version that has not been rolled back due to hackers, and the latter is the version that has. The two versions have differences and do not recognize each other. This is similar to North Korea and South Korea, which used to be one country but have now completely become two countries that do not recognize each other.

  ETC and ETC at the same time Existence, mutual non-interference

Therefore, hard forks are risky, and there is no guarantee that the entire network will agree every time. Therefore, the Bitcoin world prefers soft forks, which are much less risky.

What is a soft fork? That is, although the version has changed, it can be upgraded or not, and everyone is still in the same network. Everyone knows that each state in the United States has its own laws, but they all follow the US Constitution. Soft fork is like a certain state in the United States has introduced new regulations, so it does not need to be adopted nationwide, and it will not cause division.

Bitcoin's most famous soft fork is segwit isolation witness, which can remove part of the witness information to save Bitcoin's block space without destroying 1MB without compromising security. As shown in the figure, if you approve of Segregated Witness, then you can upgrade, if you don't, you don't have to upgrade. Although different versions of clients have differences, they can still mine together.

  Soft fork: New and old versions can coexist

Soft forks are very concerned about the issue of "forward compatibility", while hard forks cannot be "forward compatible". So, you can see that Bitcoin's reforms "seem" to be small, while Ethereum's reforms are all drastic. Because the soft fork is a test of the wisdom of the core developers.

Friends who do software development may have a deep understanding of how difficult it is to add new features and keep using the old version. This is dancing with shackles, and it is very difficult to design a solution that has the best of both worlds. But Bitcoin has done it, using a lot of political trade-offs and development wisdom, and the design of each soft fork is exquisite and amazing.

The reason is that Bitcoin is a public chain with an absolutely stable "fiscal policy". This feeling is very reassuring. Bitcoin pursues the ultimate in stability. In another 10 or even 100 years, Bitcoin will not be much different from today, just like real gold. In the next 100 years, the dollar may disappear, but gold will not.

On the Ethereum side, V God is still alive, and Ethereum does not pursue ultimate security, but pursues breaking through the impossible triangle, so it is taking risks every time Do hard fork upgrades at risk. Be aware that hard forks can easily cause divisions in the community. ETC in the past, ETH PoW today.

According to previous experience, as shown in the figure, PoS Merge should have been a hard fork upgrade similar to the previous one, and no new chain would have been born. Inherit directly from the original version. At the same time, no one has ever asked about the ownership of USDT and USDC before.

  It turned out to be a technique Upgrade

But the ETHPoW team is determined to carry out another hard fork upgrade at the same height as PoS Merge. This upgrade removes the difficulty bomb and more. Here is a common mistake: ETH PoW is not the original PoW chain of ETH. Many people mistakenly think that as shown in the figure below, one goes straight and the other turns left.

If so, the orthodoxy of ETH PoW is beyond doubt.

  is often mistaken for

However, ETH The original PoW chain should be the one with the difficulty bomb, that is, the PoW chain that "does not upgrade the client". And PoS ETH is a new chain with "upgraded client". In fact, ETH PoW is also a chain with "upgraded client"! Therefore, the actual situation is as shown in the figure below. One turns left, the other turns right, and no one goes straight.

  the real situation, One goes to the left, one goes to the right, no one goes straight

So, the actual situation is: ETH PoS and ETH PoW are actually new chains generated by hard forks. It just happens to be at the same height, and the real ETH PoW original chain will die because of the difficulty bomb.

So ETH PoW is also weak in orthodoxy. In other words, if it forks today and does not choose the same height as PoS Merge, it is completely okay. Then why does it have to choose to fork at the same height as PoS ETH? The answer is Sima Zhao's heart, which everyone knows.

Someone may ask, Todd, why do you clarify these things so clearly? I think that each chain is actually a country. When you live in a country, you must figure out its legitimacy and system. Since it starts with 0x, as a citizen of the ETH world, it is natural to get to the bottom of it.

Consensus determines the height of the ceiling of a chain, and if it loses orthodoxy, it loses a lot of consensus.

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