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Comment by chippiewill | Hacker News Reader

In principle if you had enough desire among world governments you could plausibly try and legally force a blockchain fork.

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Even if that is desired and wouldn't spark a philosophical debate about wether centralized entities should get involved at all, there is a much deeper problem.

Every transaction that is occurring now on the chain will be invalidated.

That means you can't even reverse a single transaction you will have to reverse one transaction and ALL other transactions that happened after the one you want to reverse.

If that happens too often why would I want to to transact on a chain that is under constant threat to be forked off?

You're thinking too narrowly about the types of "hard forks" that are possible and what the space of all possible regulations could be. For example, one possible idea (with a lot of downsides! this is just an example, not a proposal), is that the US government could just promulgate a "US super-key" that allowed it to sign any transaction and have it be considered valid, and require users running blockchain software in relation to financial applications to respect those transactions. This would be a bad proposal for a number of reasons, but it's possible, because blockchains and the code that enforce them are inherently a social construct, an agreement made between all participants.

But the answer to "why would I want to to transact on a chain that is under constant threat to be forked off" is even simpler: It's because, in this hypothetical, the regulatory environment you operate in gives you no other choice. Unless you and everybody you transact with has the ability to boycott or subvert the regular financial system entirely (e.g. you're doing entirely black market transactions), then you'd have to fall in line if a government that was crucial to your operations or your downstream supplier's operations required it.

Anyone could start a cryptocurrency today with such a key and give it to the FBI, and if people thought that made them safer, they could buy that currency and use it.

You wouldn't have to reverse all the transactions. You could trivially create a fork (which has to be longer, and therefore have more transactions available) that includes every transaction but one from the blockchain. Well, that is you can create that fork as trivially as you can create any other fork.

Sure maybe. But that only really works if few (if not all) entities have control over the consensus mechanism.

On a regular PoW blockchain you will have to recalculate all the hashes according to the difficulty which will up to the miners.

But even if you could, it's an absolute technical nightmare.

To build an analogy that somehow fits. If you have git repo and you find out that a particular commit that you want to undo, what do you do?

- Rebase all changes to an earlier commit, remove the faulty commit and recalculate all commit hashes that follow it.

or?

- Create a new commit that reverts the old commit.

In reality you opt for option 2 99.99% of the time. The only reason you would ever want to remove a commit from history is if you accidentally exposed information to an audience that is not supposed to see it.

When you first responded to chippiewillie you talked about how forking would produce a reversal of all the transactions. That's not true, but it is what you identified as a "much deeper problem"

My apologies, I used “reverse” and “invalidate” synonymously.

Nevertheless on a public blockchain all transactions would be invalidated and that indeed is a problem.

Because everyone who received coins would have to wait again for n confirmations in order to be sure they got their money. In theory nobody should be able to add a double spend transaction to the pool but I wouldn’t bet on it.

That’s what I mean with technical nightmare.

You would have to make sure to properly identify all transactions. Possibly take down the system, exclude a single transaction. Make sure that the miner who will find the next block will include the right transactions. Make sure of that for the following block. I don’t see that happening with a large coordination effort, meaning: centralization.

And when you come to that conclusion you should probably take a step back and rethink “why are we doing all of thatch blockchain stuff when we need to rely on a central authority?”

> when you come to that conclusion you should probably take a step back and rethink “why are we doing all of thatch blockchain stuff when we need to rely on a central authority?”

I think blockchain is going to eventually die for that exact chain of reasoning.

Even if you could isolate output chains, that means many of subsequent transactions that are legit would get cancelled...

Or you would need to make more crypto cover those... Which then would destroy the whole deflationary idea with likes of bitcoin...

And do that every time a hack occurs? What would the threshold be for when that would be worth it?

Could I recover $100k that got stolen? What about $10k? $1k?

Sure, why not? You could even automate it, using a SWIFT-like messaging pipeline that all mining companies have to subscribe to. Blockchains are fundamentally a social construct, and governments have the ability to regulate the individuals who are creating the blockchain. If there was enough political will for it, you could absolutely bolt a "reversal" mechanism onto any existing blockchain. Unless you're doing your mining operation entirely on the black market, you're going to rely on the government for enforcement of your colo rent agreements, your electricity agreements, etc, so there's lots of incentive to comply.

What you have when you're done with the process you've described is a centralized banking system managed by world governments, which is what we already have. It's not perfect, but it works, and lots of people are actively working on improving it in ways that don't involve the contradiction inherent in centralized decentralization.

Yes? That's the point of my comment? I'm confused about what you're saying. I'm trying to answer your question "And do that every time a hack occurs?". The answer is yes, it's completely feasible and within the powers of a government or inter-government treaty organization to do this every time a hack occurs, because they already do. I'm not trying to say that such a system is good, just that it's possible. There is nothing "special" about blockchains that exempts them from normal government regulation.

Ah, I misunderstood what you were saying. I thought you were advocating that we should do that, and I was wondering why that would be better than the status quo.

You'd have to be forking it once a week, because there is so much stealing going on. We'd probably end up with a weekly split. Imagine how crazy that is. And of course people would make false stealing claims. Maybe you are on vacation when they reverse something that takes your money, because you have a chance to weigh in.

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