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Blockchains are an irrevocable proof of record (immutability with cryptographic proof) unlike traditional databases that need to be audited to capture all updat

Blockchains are an irrevocable proof of record (immutability with cryptographic proof) unlike traditional databases that need to be audited to capture all updates. Amazon QLDB, though private but not a Blockchain, could be used as one: For ex, creating and maintaining customer wallets (per customer coupons and discounts specific to your service). Public blockchains could be used for accounting transparency, for example, for tracking donations and spends of a non-profit. Decentralised blockchains are of course being continually redefined and reinvented, with an alternate financial complex at the forefront of it all. There are likely many more usecases, but the ones most interesting to me are global payments infrastructure being built by stellar.org, celo.org, and diem.com. See also: https://www.hyperledger.org/ https://www.hyperledger.org/

74d-fe6-2c6 6y ago
But how can a blockchain be actually and meaningfully "public" without proof of work and distributed mining establishing majority based consensus on what _is_. If you just store the equivalent of a blockchain somewhere then I don't see what benefit it provides over a database controlled by a consortium. It's all bullshit.
- nindalf 6y ago
  Presumably, there's a third party that keeps a copy of the blockchain. If you rewrite the history of your blockchain, they'll detect it. It's fair to ask why this public record needs to be in a blockchain though. You could store the record in plain HTML on a public website and have the Web Archive create periodic immutable snapshots of it.
  - 74d-fe6-2c6 6y ago
    Exacactly - you just need something equivalent to a certificate authority which signs states of the database and guarantees the correctness of the stored data.
    - ForHackernews 6y ago
      For more than a decade, this company has been publishing their hashes in the NYTimes classified ads: http://www.surety.com/digital-copyright-protection/prove-ownership http://www.surety.com/digital-copyright-protection/prove-own... (some cryptokiddies have tried to claim it as "the world's first blockchain" https://btcmanager.com/finding-the-oldest-blockchain-in-the-new-york-times-classifieds/ https://btcmanager.com/finding-the-oldest-blockchain-in-the-... apparently not understanding how much it undermines the case for wasteful proof-of-work blockchains if a classified ad does the same job)
      - diamondhandle 6y ago
        Okay, and what happens when I run a phony ad next to this one in the New York Times? What happens when I bribe the guy at the Times to accidentally use my hash rather than theirs? It’s a cute gimmick, I’ll give them that.
        haukem 6y ago
        They prove that the hash they publish in the NYTimes exists at that time. There are probably some archives which can give you an authorized copy of the NYTimes from a specific date. You can use that to prove that the hash existed at the date the NYTimes was published. This is now the hash over a hash tree, which this companies stores. With this single hash they can also prove that every document in this hash tree existed at that time. They can not add a extra document later, because this would alter the hash they published in the NYTimes. When you publish your phony ad in the NYTimes, you also prove that this phony ad existed at the date the NYTimes was published. This company probably buys one edition of the NYTimes with their add and check if the NYTimes published the correct hash, if it is wrong they will run an other add the next day with the correct hash the next day. Now they only prove that the hash existed the next day.
        mattdesl 6y ago
        The NYTimes hashes idea is brilliant, but if you were to try to scale that concept to thousands or millions of different global use cases, eventually it seems like you'd end up with a technology platform similar to a public distributed ledger, i.e. a blockchain. I'm open to hearing about any other non-blockchain solutions to this problem, though. One seems to be IOTA and their "Tangle" graph, but I don't fully understand how that could facilitate a historical record of each transaction, as (unlike a blockchain) it is not an append-only ledger.
  - DaniloDias 6y ago
    A distributed ledger eliminates the risk that the third party hosting the record can be hacked or that the operator fraudulently lies in the record.
- daniellarusso 6y ago
  A blockchain does not require anything beyond ensuring the prior entries checksums make sense. Making past entries immutable is the purpose. Proof of work and distributed mining don’t need a blockchain. Have you heard of hashcash? It is proof-of-work concept to prevent email spam. https://en.m.wikipedia.org/wiki/Hashcash https://en.m.wikipedia.org/wiki/Hashcash
  - 74d-fe6-2c6 6y ago
    what prevents the entity controlling the blockchain from recursively changing data and adjusting the checksums?
    - daniellarusso 6y ago
      Paraphrasing Achebe here: “that until the lions have their own historians, the history of the hunt will always glorify the hunter.“ This is also an issue with a 51% attack.
- anonymousDan 6y ago
  See my answer above - in cases where the participants are all known you can use BFT algorithms to prevent attacks so long as less than a third of the replicas are malicious.
- SubiculumCode 6y ago
  Proof of work is fading away, Proof of Stake is becoming the default method.
haukem 6y ago
What is the advantage of a private blockchain over a hash tree like used in git? A git commit is also irrevocable, except if you do a git rebase. How do you prevent something similar like a git rebase in a private blockchain? A public blockchain with multiple agents that do not trust each other like in BitCoin make sense to me.
- anonymousDan 6y ago
  Think of an industry e.g. like banking, where the different participants know who each other are but don't fully trust each other. Presuming each participant controls one replica in the system, then using BFT algorithms you can ensure that so long as less than a third of the participants are malicious it is not possible to perform such an attack.
  - haukem 6y ago
    You can also set up a git repository and prevent history rewrites on the central server. Some third party could also offer this as a service. Each entity can check this by doing a pull every minute in a cron job, which fails when history rewrite happened. If they detect this, their legal department can take some actions.
    - ignoramous 6y ago
      Just because Encarta existed, didn't mean Wikipedia shouldn't; or because NFS exists, Dropbox shouldn't. They can be solutions to the same problem. In git's case though, it sounds more like a abuse of its underlying properties (not to mention, you'd have to block all git commands that can rewrite history).
      - yjftsjthsd-h 6y ago
        > not to mention, you'd have to block all git commands that can rewrite history Okay, so use mercurial or fossil.
  - acdha 6y ago
DebtDeflation 6y ago
>an irrevocable proof of record (immutability with cryptographic proof) Which ignores and can even make worse the problem of bad data at the entry point. This is what effectively killed the entire set of use cases related to supply chain provenance.

74d-fe6-2c6 6y ago

But how can a blockchain be actually and meaningfully "public" without proof of work and distributed mining establishing majority based consensus on what _is_. If you just store the equivalent of a blockchain somewhere then I don't see what benefit it provides over a database controlled by a consortium. It's all bullshit.

nindalf 6y ago
Presumably, there's a third party that keeps a copy of the blockchain. If you rewrite the history of your blockchain, they'll detect it. It's fair to ask why this public record needs to be in a blockchain though. You could store the record in plain HTML on a public website and have the Web Archive create periodic immutable snapshots of it.
- 74d-fe6-2c6 6y ago
  Exacactly - you just need something equivalent to a certificate authority which signs states of the database and guarantees the correctness of the stored data.
  - ForHackernews 6y ago
    For more than a decade, this company has been publishing their hashes in the NYTimes classified ads: http://www.surety.com/digital-copyright-protection/prove-ownership http://www.surety.com/digital-copyright-protection/prove-own... (some cryptokiddies have tried to claim it as "the world's first blockchain" https://btcmanager.com/finding-the-oldest-blockchain-in-the-new-york-times-classifieds/ https://btcmanager.com/finding-the-oldest-blockchain-in-the-... apparently not understanding how much it undermines the case for wasteful proof-of-work blockchains if a classified ad does the same job)
    - diamondhandle 6y ago
      Okay, and what happens when I run a phony ad next to this one in the New York Times? What happens when I bribe the guy at the Times to accidentally use my hash rather than theirs? It’s a cute gimmick, I’ll give them that.
      - haukem 6y ago
        They prove that the hash they publish in the NYTimes exists at that time. There are probably some archives which can give you an authorized copy of the NYTimes from a specific date. You can use that to prove that the hash existed at the date the NYTimes was published. This is now the hash over a hash tree, which this companies stores. With this single hash they can also prove that every document in this hash tree existed at that time. They can not add a extra document later, because this would alter the hash they published in the NYTimes. When you publish your phony ad in the NYTimes, you also prove that this phony ad existed at the date the NYTimes was published. This company probably buys one edition of the NYTimes with their add and check if the NYTimes published the correct hash, if it is wrong they will run an other add the next day with the correct hash the next day. Now they only prove that the hash existed the next day.
        mattdesl 6y ago
        The NYTimes hashes idea is brilliant, but if you were to try to scale that concept to thousands or millions of different global use cases, eventually it seems like you'd end up with a technology platform similar to a public distributed ledger, i.e. a blockchain. I'm open to hearing about any other non-blockchain solutions to this problem, though. One seems to be IOTA and their "Tangle" graph, but I don't fully understand how that could facilitate a historical record of each transaction, as (unlike a blockchain) it is not an append-only ledger.
- DaniloDias 6y ago
  A distributed ledger eliminates the risk that the third party hosting the record can be hacked or that the operator fraudulently lies in the record.
daniellarusso 6y ago
A blockchain does not require anything beyond ensuring the prior entries checksums make sense. Making past entries immutable is the purpose. Proof of work and distributed mining don’t need a blockchain. Have you heard of hashcash? It is proof-of-work concept to prevent email spam. https://en.m.wikipedia.org/wiki/Hashcash https://en.m.wikipedia.org/wiki/Hashcash
- 74d-fe6-2c6 6y ago
  what prevents the entity controlling the blockchain from recursively changing data and adjusting the checksums?
  - daniellarusso 6y ago
    Paraphrasing Achebe here: “that until the lions have their own historians, the history of the hunt will always glorify the hunter.“ This is also an issue with a 51% attack.
anonymousDan 6y ago
See my answer above - in cases where the participants are all known you can use BFT algorithms to prevent attacks so long as less than a third of the replicas are malicious.
SubiculumCode 6y ago
Proof of work is fading away, Proof of Stake is becoming the default method.

haukem 6y ago

What is the advantage of a private blockchain over a hash tree like used in git? A git commit is also irrevocable, except if you do a git rebase. How do you prevent something similar like a git rebase in a private blockchain? A public blockchain with multiple agents that do not trust each other like in BitCoin make sense to me.

anonymousDan 6y ago
Think of an industry e.g. like banking, where the different participants know who each other are but don't fully trust each other. Presuming each participant controls one replica in the system, then using BFT algorithms you can ensure that so long as less than a third of the participants are malicious it is not possible to perform such an attack.
- haukem 6y ago
  You can also set up a git repository and prevent history rewrites on the central server. Some third party could also offer this as a service. Each entity can check this by doing a pull every minute in a cron job, which fails when history rewrite happened. If they detect this, their legal department can take some actions.
  - ignoramous 6y ago
    Just because Encarta existed, didn't mean Wikipedia shouldn't; or because NFS exists, Dropbox shouldn't. They can be solutions to the same problem. In git's case though, it sounds more like a abuse of its underlying properties (not to mention, you'd have to block all git commands that can rewrite history).
    - yjftsjthsd-h 6y ago
      > not to mention, you'd have to block all git commands that can rewrite history Okay, so use mercurial or fossil.
- acdha 6y ago

DebtDeflation 6y ago

>an irrevocable proof of record (immutability with cryptographic proof) Which ignores and can even make worse the problem of bad data at the entry point. This is what effectively killed the entire set of use cases related to supply chain provenance.