This article is translated from Authorito Capital CEO’s blog post WTF is The Blockchain? “And” Who Owns Blcockchain, “slightly abridged. Original link: medium.com/mohitmamo… hackernoon.com/wtf-is…
Let’s think of the blockchain as a ledger. Each block is each page of the ledger, and when the page is full, it needs to be sealed with a “password” (hash) and stored in a folder.
Now imagine that there are already five pages of content in this folder, all sealed with a “seal password.” What if I went back to page 2 and changed some of the transaction data to benefit me? The seal code would let everyone see the inconsistencies in the transaction, right? What if I recalculated a seal password for the changed content and marked it on the page?
There’s a trick here to keep the seal code from being changed
Remember what I told you earlier? There are two boxes, one containing the number 20893 and the other empty, waiting for the player to calculate a value that will add the contents of the two boxes to get the result we want.
In fact, calculating the seal password for a blockchain is more complicated, requiring three boxes instead of two. Two of these boxes are pre-loaded, one containing all the transactions on the page, another containing the results of the previous page processed by the “magic machine” (hashed encryption), and the third containing the seal code calculated by the player himself. When all three boxes are filled and fed into the machine, the output from the right side of the machine must meet our preset conditions.
This clever “trick” in blockchain ensures that each page is sealed by relying on the previous one. Therefore, if someone wants to change the content of a page that has been sealed, he must change the content of all previous pages and the seal password to ensure the consistency and continuity of the chain.
At the beginning of the last article, we assumed that there were 10 players, and if one of these players tried to cheat everyone and change a page of the ledger, he would have to change many pages and recalculate the seal codes on those pages. We all know how hard it is to calculate the seal code! From the page he changes, he has to create another link in the network. But the chain can never catch up with the honest chain maintained by the other nine men, for the working ability and speed of one man cannot keep up with the working ability and speed of nine men put together. Thus, the longest chain is guaranteed to be the “honest” chain. So, in this game, one dishonest guy can’t beat nine honest players, he can’t fix it.
What if not one, but six people become dishonest?
The technical term for this is a “51 percent attack.”
If most people in the network become dishonest and cheat others in the network, the blockchain protocol will fail. While this is highly unlikely to happen, we should also be aware of the fragility of blockchain systems, which are based on the assumption that the majority of a crowd is always honest.
So in blockchain, if a person can master 51 percent of the system’s computing power, they can rewrite the data in the blockchain to their advantage.
What does “51% of the computing power in the system” mean?
The amount of CPU power and power used by players in the system to account for and calculate the “seal code” is what we call computing power.
How to solve this problem
Some solutions have been proposed, such as “proof of stake” approaches that do not rely on computer power. Proof of equity is when players in the system, instead of solving mathematical puzzles to work out the “seal code,” bet their coins on their proposed solution. If a majority of people agree, the player gets the reward. If the majority disagree, the player’s previous bet is deducted from his wallet. This approach introduces a penalty scheme.
But there are problems with this approach. While dishonest guys are punished, it also results in the system of “the rich getting richer and the poor getting poorer”. If I win this bet and get a reward, I’ll bet more coins next time, win the bet and bonus again, and put more assets in. Over and over again, most of the assets in the blockchain end up in the hands of very few people. If the people who control most of the wealth want to rewrite blockchain, they can.
In any case, as long as a few people get their hands on the blockchain, the majority of people in the blockchain are at risk.
There’s a conversation between Vitalik and others on Twitter: Bug Spencer: What’s the difference between rules specified by banks and rules specified by core developers? Both depend on others. Vitalik Buterin: If you found out that JP Morgan had abused its power and cheated you, would you separate out a “JP Morgan classic” from other unhappy JP Morgan clients?
Vitalik’s point is that if a blockchain has users who are not happy with its rules, those users can split off and recreate a forked chain, like the Ethereum blockchain and the Ethereum blockchain.
This method is not entirely applicable, but it is a method.
Is there a better plan? There will be, after all, so many blockchain enthusiasts are working on it.
This article is originally from universal blockchain and is not allowed to be reproduced without authorization.