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Comment by DantesKite | Hacker News Reader

> I also think that relatively few real-world problems are made easier by blockchain's strengths - and many of them are situations where you're seeking to avoid some kind of censorship. I think avoiding censorship is important and I'm glad we have a technology that is useful there - but by volume most human interactions do not have to worry about censorship.

What's funny about that is China is adopting blockchain technologies specifically to bind together databases for tracking social credit scores across different provinces because they've previously been silo'ed and unable to communicate with each other in a straightforward way (for whatever reason).

China is banking on blockchain technologies precisely because it's can be such a powerful censorship tool.

https://decrypt.co/39905/blockchain-now-powers-parts-of-chin...

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this post makes absolutely no sense. blockchains are useful in situations where you need consensus between potentially adversarial parties. the benefits of trustless coordination have tradeoffs that make blockchains less efficient than traditional databases or computational systems. there is zero advantage and significant additional cost & complexity for a centralized body (the CCP), which has direct control over all subsidary participants, using a blockchain to collate disparate databases. this is a meaningless PR release.

> tracking social credit scores across different provinces because they've previously been silo'ed and unable to communicate with each other in a straightforward way (for whatever reason).

does this sentence mean something to you? what does a blockchain do in this situation?

China's provincial officials are potentially adversarial parties vs the central government. Officially they must do as they are told, but unofficially they have considerable independent power as long as they aren't caught.

Only a guess, but I suspect that Covid got as bad as it did partly because Wuhan officials didn't want the central government to know how bad things were (at least at first).

A block chain doesn't help with this situation though since only the central authority matters. If a adversarial party submits false data, blockchain doesn't do anything to address that.

The situation you describe can be handled via a write-only log with cryptographic signing of each change.

This is partially correct, China is not a monolithic entity that fully marches in lockstep with Beijing.

But the solution to the problem of uncooperative governors is the application of soft power (media, agitprop, appointments, rewards, threats, denunciations and disappearances, liquidation of problem people, their families, their friends, their pets, etc), not some over-engineered technological non-solution that still relies on the cooperation of all the parties in question to work.

A blockchain can't enforce that anyone actually enters data into it, or that the data that is entered isn't garbage. A snail-mail package containing data sent to Beijing has the exact same immutability property for the only party that cares about it - the national government.

Something like a blockchain is useful when peers don't trust eachother, but all care to build a shared consensus. When the peers don't care about consensus, and a central authority with the power of pit and gallows exists, none of those usecases hold.

I didn't mean to imply that a blockchain is a good solution here.

And in a system where it's considered sometimes desirable to erase inconvenient history, an immutable ledger doesn't help with that.

The 21st century in the Western world has taught us that we don't need to physically erase inconvenient history, you just need to shout the new version of history loudly enough.

George Orwell was mistaken when he thought that anyone would care about facts, figures, and how much sugar was rationed every week. You just need to tell people that it's raining while you piss on them, and they'll believe you.

But how does blockchain help here, compared with other ways of syncing data?

You'd be stupid to use, say, ETH to do it when you can simply have multiple parties sign and publish events in a distributed append-only log, which they keep syncronised. That doesn't need PoW or to be a currency.

How do you deal with multiple copies with different signing parties who claim to have the true copy?

Erm the entire point of having multiple parties sign is you get the quorum which is how you avoid this issue.

Sure, you have a limited number of participants and some tweaking to do on the quorum (in some cases you might want all parties to sign).

But hey - the blockchain cool-aid gang tried to sell it as a solution for COVID contact tracing. Which is beyond laughable. The entire industry is a shillfest.

Without the blockchain consensus mechanism, how else can you guarantee the log has only be appended?

With a hash chain[0], an idea from 1981.

[0] https://en.wikipedia.org/wiki/Hash_chain

I am interested in this and I have an emotional desire for you to be right; I'm skeptical of every application I've ever seen for blockchain.

That being said, it is not clear to me how a hash chain guarantees that the data it stores hasn't been modified.

Okay, maybe I should have posted the link to the Merkle tree page[0] instead.

The basic idea is, you have a chain of 'transactions' (like in bitcoin or think git commits) und you store the hash of the content + the hash of the member before as a checksum. This way, if you alter the log file, the hash for the modified entry is suddenly different, and the chain breaks, because the next member used your hash as input to calculate their checksum. So you can not only see that the file was tampered with, you can also say which entry was modified.

Edit: Merkle trees[0] generalize this concept into trees, which are e.g. used in ZFS (the file system), git and in the blockchain.

[0] https://en.wikipedia.org/wiki/Merkle_tree

It seems to me that if you have a copy of the information locally and compare it to the remote, you can see whether they diverged with or without a hash - the hash certainly makes it faster, but it's not clear to me that a hash chain or a Merkle tree offers a guarantee that's as powerful as the blockchain's promise.

(Social factors and forks to change our minds on blockchains notwithstanding)

Like git. The value isn't necessarily in that there can't be conflicts, but that conflicts are straightforward to surface and resolve.

Anti-Corruption tech. If everyone's scores are just stored in a SQL databse, people can pay off officials to change their grade, Ferris Bueller-style. Blockchain prevents any province or official from having superuser power over the data.

That would make sense if: - There weren't other methods to prevent tampering - Governments didn't want anti-corruption methods without having admin powers to exclude themselves.

This doesn't really make sense. We have SQL databases with permissions to prevent tampering, and audit logs, and myriad other solutions.

In addition, I don't see what prevents an "official" from writing a social credit transaction (disclaimer that I have no idea how China's "social credit" system works or even what it is) to the blockchain. Nodes validate to solve disagreements where one node says a transaction happened that did not. This does not appear to be the same type of dishonesty being referred to here.

You can achieve this in a SQL database with proper processes, auditing and controls.

The world has functioned up until the magical dawning of the blockchain.

The other ways require you to trust the operators of other nodes you sync with.

The only between-nodes trust blockchain relieves you of is trust in the history of a multiparty transaction log.

A blockchain doesn't prevent individual parties from lying about things only they would know about -- if that's what's on your chain, you still need trust.

Same question that comes up with nearly every such application of crypto-tech in business or government: Why can't they just do that with a database?

Corruption. They don’t trust their own people with data.

Blockchain adds a level of certainty that history hasn’t been changed, and you can at least audit any undo-type actions; it’s the same reason certificate transparency logs and git are built on blockchain-esque technology.

`git push -f` can absolutely do the type of "history changing" that you claim it can't though. CT logs are also quite vulnerable to attacks where the root of the certificate chain gets compromised, for example because they are being threatened by their government. Even blockchains are only protected from history rewriting as long as no 51% attack takes place, and all but the largest blockchains are quite vulnerable to this.

I question this idea of history writing and it being a huge problem.

How far down the chain could a 51% blockchain rewrite occur before consuming all of the computation power of the universe?

I have seen arguments in which the 51% steals all of the new coins but how long can that be maintained, the other 49% needs to pay their bills and audits would inevitably out the bad players. Eventually, the last bitcoin will be minted, making the whole issue mute.

51% attacks don't rewrite history, they rewrite accepted history (with accepted further narrowly defined to mean "accepted for transactional purposes"). It's not like the other 49% are under any sort of obligation to delete the alternative chain from their hard drives.

Additionally a bit flip in a CT (cert transparency) log rendered it invalid and dead. This cannot happen in a peer to peer consensus protocol as the bad block would have been rejected by the working nodes. CT is good tech but it superficially is a private issued blockchain without most of the benefits of public peer to peer electronic cash and digital asset systems.

So when does something stop being “git” and start being “blockchain technology”? When the latter sounds better to investors?

When there are multiple actors incentivized to ignore any history-rebasing. Of course if you're running your own git repo, you know your githashes will change if you go back in history and change something, and it doesn't matter. When multiple people want to ensure that history hasn't changed, they can compare their hashes with yours, and have good evidence of who tampered with the history and ignore them / prosecute them.

I’m unable to find a single article that actually details what “blockchain technology” they’re using, and why. Every English article seems to be a rehash of the same press release - Can anybody find something better in mandarin ?

Department of Homeland Security also likes blockchain tech, for various 'transparency' reasons:

https://www.dhs.gov/science-and-technology/blockchain-portfo...

There are many anti-fraud and enhanced supply chain tracking notions associated with blockchain tech. Of course, those are all enabled with this form of 'surveillance.'

Based on what you've described, they are using blockchain for their censorship tool, but that's different from the blockchain being a censorship tool in and of itself.

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