[margalabargala]

> A blockchain is the logical extreme of where you end up when you think about how to sync backups

It's not. Blockchains are only eventually consistent among nodes. They're designed for synced backups among adversarial peers.

There's no reason for a government agency to use one internally. There are better ways to sync backups when the people with access to make updates are also authorized to do so.

[c7b]

Internally, you don't need it, agreed. But that is centralization risk exemplified in this incident. Which isn't necessary. Every notary could be a node. It would be a lot more resilient, and it would look a lot like a blockchain (not necessarily with a crypto currency though) if you do it properly.

[margalabargala]

You can have decentralization without blockchain. A defining feature of blockchain is that each node depends on the precise ordering of prior nodes which is a huge liability if you have network disruptions, etc, in a bureaucracy.

A git repo with cryptographically signed commits solves all the same problems without the headache.

[c7b]

Agreed that you don't need total ordering and hence consensus for pure asset transfers. But if you want to make any changes at all, like updating the list of nodes, you do. So in practice, you do need it. Every other proposal will fall short in a critical and avoidable way. Amending your git proposal with the necessary parts will turn it into a blockchain.

[margalabargala]

Disagree. We're talking real estate here. The time between transactions is months to years, not seconds to minutes. A git history will work fine. If there are racing transactions against the same piece of real estate, that's probably fraud, not something that should be automatically resolved.

[c7b]

git as-is is completely unfit for purpose and a huge security risk for this use case, because it uses MD5, which is no longer collision-resistant.

If your proposal is 'something like git, with a few modifications to make it suitable for this use case', then that's exactly what I'm proposing. What you will need, once you've considered all requirements to the best extent feasible, will be a blockchain. Eg you do need the ability to make protocol updates, no matter the time scale of transactions.

[margalabargala]

> git as-is is completely unfit for purpose and a huge security risk for this use case, because it uses MD5, which is no longer collision-resistant.

Firstly, git does not use MD5. It uses SHA1.

Secondly, since 2017 git has shipped with an implementation of SHA1 (sha1dc) that detects the collision attack you describe, which for this use case renders it a non-issue.

Thirdly, git supports `git init --object-format=sha256` which removes the whole issue for anyone who cares to do so.

I think git as-is solves the problem nicely. The only additional value blockchain provides is the ability for someone to point at it and say "look! A use for blockchain exists!" which isn't worth the downsides it'll bring.

[homakov]

You can't do any real money/real estate transactions without canonical order (chain of events). that's why git analogy is not applicable here. You'd need "main" branch to be canonically finalized for each and every participant.

[margalabargala]

What? Sure you can. All you need is confidence in the current owner. You don't need the whole history. Can you imagine the poor store clerk trying to say "sorry sir I can't accept that $20 bill unless you can name every prior owner in order".

Not sure if you're being deliberately obtuse here but this isn't an issue with the cadence of real estate transactions. Real estate ledgers do not need to support HFT.

[homakov]

Never said you need to store the whole history at all times, i said it must be established in canonical way. Storing latest state is just fine. Event Sourcing works this way too, and allows caching recent state.

[codedokode]

If every notary is a node, you need some mechanism to ensure they perform only legitimate transactions and constantly monitor them. It is easier to just have a central authority.

[c7b]

You need that anyway. It's not technology that's stopping notaries from falsifying transactions in the current system.