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As a really quick hint, if somebody pushes blockchains as a solution for anything but cryptocurrency and managing cryptocurrency based on the state of other cry

As a really quick hint, if somebody pushes blockchains as a solution for anything but cryptocurrency and managing cryptocurrency based on the state of other cryptocurrency, or a solution for Zooko's Triangle, they're selling a lie. EDIT: the reason for this is that if the chain ever needs to touch something that isn't entirely stored within the chain - for example, the number of avocados picked on a certain day - it needs a trusted oracle to tell it that. If you have a trusted oracle, you can trust that oracle to host a bog-standard SQL database and avoid this whole mess, unless your boss is breathing down your neck about using "blockchain" so your company can look cool and hip to its investors/clients.

rocqua 9y ago
What about a registry of land ownership? That could be tracked fully on a blockchain with the added advantage of no longer needing to trust some centralized office to 1) correctly track ownership and 2) properly store their records. A similar idea exists for tracking ownership of domain names. There are other cases where you trust the oracle but want some form of non-equivocation. A nice example is a notary. In that case, just an SQL database doesn't suffice. Sometimes, something like a pgp-signed statement could work for that. If you want some more resilience against the claim 'that was signed with a fake key' you could mandate all signatures be published on an actual block-chain. This time-stamps them so you can see whether they happened before a key compromise, and allows the requirement that the counter-party audits the blockchain to ensure that no signatures are published that they did not know of. This audit would mean that signatures published with a compromised key would quickly be detected. This way, the records of the notary are publicaly checkable. You now only need to trust the notary at the time of publishing their signature on the blockchain (with some extra time to ensure they can't claim to not have audited yet).
- mythrwy 9y ago
  Public records does seem like a reasonable use case. Birth, death, marriage, ownership etc. Not sure it's a lot better than what we have now but it might be cheaper. (Or the reverse.)
  - rocqua 9y ago
    With public records, a big question is whether you need some form of distributed Sybil resistant consensus.
- vertex-four 9y ago
  > What about a registry of land ownership? Towards what purpose? So that a court can look at it and decide who owns the land? In which case the court can run a SQL database for significantly cheaper than a secure proof-of-work system. The notary idea is a good one, except that it's not actually a problem that needs solving in most countries with a semi-functioning democracy. If you want to timestamp something relatively important, you post it in your city/county/country's newspaper of record. In the UK, for example, that'd be The London/Edinburgh/Belfast Gazette. Various entities maintain copies of these, in case you're worried that the Government decided to edit their copy of the record.
  - rocqua 9y ago
    Consider title insurance [1]. The current system of land registry in the U.S. is so disjointed that you need insurance against the registry making mistakes. This might be solved by making a centralized database, but then we are depending on the technical capabilities and security of the court system. Just because we trust the court to make correct decisions does not mean we trust the court to keep that data correctly and publicly available. Besides, a system like this could allow for land transfers that are recorded only in the blockchain, without need of an intermediary. A harder objection would be complicated deeds. For example, a deed that grants a piece of land but requires that, when it is sold, the proceeds go to some charity. For cases like that, you'd require a signature by a trusted third party (an oracle). We are now trusting that oracle only to make the right decision when the signature is requested. Moreover, it is now public data that there is a complex deed behind this transaction. Thus it is no longer possible that upon sale, the deed has been forgotten and then later it turns up wreaks retroactive havoc. Another issue would be 'property loss'. People lose their crypto keys all the time, what happens when people lose the 'key' to their land? [1] https://en.wikipedia.org/wiki/Title_insurance https://en.wikipedia.org/wiki/Title_insurance
spurcell93 9y ago
I won't claim to be an expert on this, but isn't that the whole point of multiple / decentralized oracles?

rocqua 9y ago

What about a registry of land ownership? That could be tracked fully on a blockchain with the added advantage of no longer needing to trust some centralized office to 1) correctly track ownership and 2) properly store their records. A similar idea exists for tracking ownership of domain names. There are other cases where you trust the oracle but want some form of non-equivocation. A nice example is a notary. In that case, just an SQL database doesn't suffice. Sometimes, something like a pgp-signed statement could work for that. If you want some more resilience against the claim 'that was signed with a fake key' you could mandate all signatures be published on an actual block-chain. This time-stamps them so you can see whether they happened before a key compromise, and allows the requirement that the counter-party audits the blockchain to ensure that no signatures are published that they did not know of. This audit would mean that signatures published with a compromised key would quickly be detected. This way, the records of the notary are publicaly checkable. You now only need to trust the notary at the time of publishing their signature on the blockchain (with some extra time to ensure they can't claim to not have audited yet).

mythrwy 9y ago
Public records does seem like a reasonable use case. Birth, death, marriage, ownership etc. Not sure it's a lot better than what we have now but it might be cheaper. (Or the reverse.)
- rocqua 9y ago
  With public records, a big question is whether you need some form of distributed Sybil resistant consensus.
vertex-four 9y ago
> What about a registry of land ownership? Towards what purpose? So that a court can look at it and decide who owns the land? In which case the court can run a SQL database for significantly cheaper than a secure proof-of-work system. The notary idea is a good one, except that it's not actually a problem that needs solving in most countries with a semi-functioning democracy. If you want to timestamp something relatively important, you post it in your city/county/country's newspaper of record. In the UK, for example, that'd be The London/Edinburgh/Belfast Gazette. Various entities maintain copies of these, in case you're worried that the Government decided to edit their copy of the record.
- rocqua 9y ago
  Consider title insurance [1]. The current system of land registry in the U.S. is so disjointed that you need insurance against the registry making mistakes. This might be solved by making a centralized database, but then we are depending on the technical capabilities and security of the court system. Just because we trust the court to make correct decisions does not mean we trust the court to keep that data correctly and publicly available. Besides, a system like this could allow for land transfers that are recorded only in the blockchain, without need of an intermediary. A harder objection would be complicated deeds. For example, a deed that grants a piece of land but requires that, when it is sold, the proceeds go to some charity. For cases like that, you'd require a signature by a trusted third party (an oracle). We are now trusting that oracle only to make the right decision when the signature is requested. Moreover, it is now public data that there is a complex deed behind this transaction. Thus it is no longer possible that upon sale, the deed has been forgotten and then later it turns up wreaks retroactive havoc. Another issue would be 'property loss'. People lose their crypto keys all the time, what happens when people lose the 'key' to their land? [1] https://en.wikipedia.org/wiki/Title_insurance https://en.wikipedia.org/wiki/Title_insurance

spurcell93 9y ago

I won't claim to be an expert on this, but isn't that the whole point of multiple / decentralized oracles?