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Comment by throwthrowuknow | Hacker News Reader

Blockchains don’t have to be decentralized and you can undo a transaction by making a new transaction that reverses the changes.

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Without decentralization, doesn't that mean you don't even need a 51% attack... the central authority can just rewrite the ledger history at will, the same as any database or git history?

It’s a government agency, I don’t think they’re doing this with the intent of giving up that authority.

So what does the blockchain actually accomplish...?

Nothing. As is tradition.

Just a different way of having an auditable and verifiable transaction history. Maybe it’s easier to share the blockchain than it would be to share copies of the database? They could be leveraging the existing tools for copying and verifying it, perhaps one of the requirements is that end users or dealers need to have access to a local copy that they can use to check the ownership history of a vehicle before a purchase? Everyone loves to hate on anything blockchain but it’s a useful data structure.

I don't think this really makes sense...? A blockchain is awesome for decentralized verification of a shared ledger, but without that, it's no different than a line by line history of writes in a text file.

If a dealer has a local copy of the ledger but isn't really part of the blockchain consensus, it's no different than having a read only history in any other structure.

It doesn't matter what format you store it in, it's more a question of who can rewrite history. If the central authority can do so at will and nobody can disagree with them, it nullifies the benefits of using a blockchain.

The dealer can say "it doesn't match our records", sure, but they can say that no matter if a blockchain or a bunch of CSVs are used. If the DMV then says sorry, our records are the only authoritative ones, please overwrite yours... then we're right back where we started.

I don't think people hate blockchains as a data structure, but as misapplied snake oil that doesn't solve the underlying problems. This doesn't create a real audit trail as much as the illusion of one. A proper audit trail would require the authoritative history to reside elsewhere, in some independent third party that the DMV cannot unilaterally overwrite.

What's the point than?

Auditable history.

You don't need blockchain for that, you can just use git.

Git is a blockchain

No; it's a hash tree.

Blockchain is also a hash tree, but not all hash trees are blockchain. They've been around since the 70s.

They’re functionally equivalent these days. Blockchain has become marketing speak mostly.

But if you squint a little. The history of a git branch sure looks a lot like a blockchain (or vice versa). You have a ledger of records (commits), that are append only, and each commit contains a merkle or hash tree (git tree object)

So yeah git is basically a blockchain.

I have to squint pretty hard to convince myself. Git itself really only covers the auditing part, which any static service will do by virtue of storing data. Git repos aren't decentralized, they rely entirely on external software like GPG and SSH to enforce identity and have no native consensus mechanism. They also don't protect from erasing transactional history which is kinda seen as the cardinal sin of ledger-based economics.

If you wanted to be reductive you could try to argue that all linked lists or hashmaps are a blockchain once compiled. I think that's silly, bordering on revisionism. Git wasn't programmed as a Blockchain, and Blockchains weren't intended to resemble Git.

> Git repos aren’t decentralized

Sure they are. Git is one of the pioneering “distributed” version control systems. Every clone of a git repo is a complete copy. Sounds pretty decentralized to me.

Git’s native consensus mechanism is to defer to humans and record their decisions as merge commits.

I agree git natively doesn’t protect against erasing history. Although rebase is discouraged and any one node can’t forcibly erase history from every other node.

> Every clone of a git repo is a complete copy. Sounds pretty decentralized to me.

Every clone of a DNS lookup table is a complete copy too. That doesn't change the fact that DNS is one of the least decentralized technologies being developed and propagated today.

That’s more a question of how you hold it.

You can keep your own local DNS list or run one for you and your friends (OpenNIC)

But for DNS it’s typically most convenience if everyone agrees on who google.com is.

lol

Databases do that just fine.

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