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> How can data be retracted from a blockchain? In much the same way data can be retracted from printed copies of newspapers that already have widely circulated copies in both personal and institutional/library hands: by publishing a subsequent retraction later in the chain, like any other change.
The change and what was previously there is left for anyone to see in the blockchain.
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> why would any real business want to use a public blockchain? I think it is only important for a business when public trust is important. For example, a news agency could publish its articles in a public blockchain so the original article and any updates to that article would forever be auditable from that blockchain.
It's exhausting arguing with the same bogus "use cases" every other week but here goes in short: - In your scenario you're not decentralized, you have a clear authority: the news agency - The news agency can broadcast a signed merkle tree of the articles it publishes alongside the normal newspaper/news program etc... For instance through their website. - Anybody who cares about it could maintain a copy of this signed…
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> why would any real business want to use a public blockchain? I think it is only important for a business when public trust is important. For example, a news agency could publish its articles in a public blockchain so the original article and any updates to that article would forever be auditable from that blockchain.
It's exhausting arguing with the same bogus "use cases" every other week but here goes in short: - In your scenario you're not decentralized, you have a clear authority: the news agency - The news agency can broadcast a signed merkle tree of the articles it publishes alongside the normal newspaper/news program etc... For instance through their website. - Anybody who cares about it could maintain a copy of this signed…
>- In your scenario you're not decentralized, you have a clear authority: the news agency Only due to current technical limitations. Shift to Blockchain, get distributed news agencies, with reporters[1] residing all over the world. Think of the time and costs saved by not having to send reporter out of a central office
>- The news agency can broadcast a signed merkle tree of the articles it publishes alongside the normal newspaper/news program etc... For instance through their website. Doesn't help a bit, given how they have total control over the content of the website, they could just as easily swap out the merkele root and claim it is the original one. Blockchain denies them this sleight of hand.
>- Anybody who cares about it could maintain a copy of this signed tree locally. ...and there's a well known tool for distributing that in a verified & timestamped format - Blockchain.
>- If the news agency censors or edits an article anybody with a copy of the original tree can prove it by showing that their tree has a valid signature from the news agency and yet the hashes don't match. Introduces a 'he-said, she-said' problem. Which the Blockchain neatly avoids.
[1] possibly with a lot more "citizen journalists" who do the reporting as a side activity, rather than mostly plain old full-time journalists.
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> why would any real business want to use a public blockchain? I think it is only important for a business when public trust is important. For example, a news agency could publish its articles in a public blockchain so the original article and any updates to that article would forever be auditable from that blockchain.
It's exhausting arguing with the same bogus "use cases" every other week but here goes in short: - In your scenario you're not decentralized, you have a clear authority: the news agency - The news agency can broadcast a signed merkle tree of the articles it publishes alongside the normal newspaper/news program etc... For instance through their website. - Anybody who cares about it could maintain a copy of this signed…
So then the problem is, I need to go to some entity that is famous enough. And I need my tree to connect to theirs. And all this on the cheap. I'm not a aware of any such thing in existence.
Another nice thing about the blockchain is that the timestamps of the signatures are provable.
And also nice is that there are no record keepers to whom which pressure can be applied.
Cryptocurrencies, and especially Ethereum, are truly novel innovations in computer science that cross many academic disciplines. The linked example is a great write-up. It’s sad that there is a vocal group, especially on HN, that knee-jerk hates everything blockchain related and wishes with their entire being for it to fail. However, I think smart contracts are fascinating and wish more people would keep an open mind…
The term “Smart contracts” (Ethereum/EOS/hyperledger) is often used with wild claims for supply chains and cross border business deals, but why would any real business want to use a public blockchain? Smart contracts can’t even do anything interesting without a trusted source of data input. The threat model and legal questions of smart contracts are another huge deterrent for most businesses. Latency, throughput, sec…
As the locus of economy shifts more and more away from physical widgets and into information, the value of information goes up in relation to physical widgets. This makes Blockchain a practical, if not all-encompassing, tool for verification.
Compare a plain old car - the software onboard is a small fraction of its value - to any half-decent workstation, where the value of software can easily exceed the hardware's value several-fold.
Proving I had certain information at certain time point - e.g., a license for the software, or CAD design or other valuable file I've created - can easily provide a lot of value. And in this case "trusted source of information" is the mere fact of existence of a cryptographically secured license file naming me as the licensee at certain time point. Easily securable with the Blockchain.
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The term “Smart contracts” (Ethereum/EOS/hyperledger) is often used with wild claims for supply chains and cross border business deals, but why would any real business want to use a public blockchain? Smart contracts can’t even do anything interesting without a trusted source of data input. The threat model and legal questions of smart contracts are another huge deterrent for most businesses. Latency, throughput, sec…
Smart contracts can’t even do anything interesting without a trusted source of data input. ...for a certain definition of "doing anything interesting", just as well as "trusted source"*. As the locus of economy shifts more and more away from physical widgets and into information, the value of information goes up in relation to physical widgets. This makes Blockchain a practical, if not all-encompassing, tool for veri…
The blockchain solves the problem of proving ownership of a transferable asset. If you just want to prove that you have certain information at a certain time point there are much simpler solutions: Publicly release the hash of a message (let's say: "I created this using the licence key XXX-XXX-XXX" + signature from your private key) on Twitter/Facebook/Github/Archive.org etc.
Or even better: Sign a contract and send it to your law firm. Once someone breached a licence/contract you need to involve lawyers/regulators anyway.
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The change and what was previously there is left for anyone to see in the blockchain.
And printed copies are not?
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It's exhausting arguing with the same bogus "use cases" every other week but here goes in short: - In your scenario you're not decentralized, you have a clear authority: the news agency - The news agency can broadcast a signed merkle tree of the articles it publishes alongside the normal newspaper/news program etc... For instance through their website. - Anybody who cares about it could maintain a copy of this signed…
If I personally published a signed merkle tree... I think I'm too much of a nobody for people to download it to keep me honest you know. Unless I pay them to do it of course. So then the problem is, I need to go to some entity that is famous enough. And I need my tree to connect to theirs. And all this on the cheap. I'm not a aware of any such thing in existence. Another nice thing about the blockchain is that the ti…
In the original scenario I assumed that there were third party people interested in detecting or even preventing modification of articles after they're published. If nobody cares about it then the whole thing is moot to begin with.
If your scenario is that you'd like to be able to timestamp data that has value to you but not others (say, something patent-related) then it's a different scenario and then yes, the blockchain might make sense, although you could also use many other trusted, albeit centralized, third parties to achieve the same thing. Making a public post of Facebook or some other big website for instance. The incentives would have to be very high for these companies to modify post dates for a scam. Even more so if you post it to several websites. I think there are also services who will add your signature to a merkle tree and then publish it in a newspaper for instance.
But I agree that in this situation publishing the hash on a blockchain is actually a good solution. It's simple and easy to program for. But keep in mind that this only works as long as the currency is valuable enough to keep miners honest and rewarded for their work (otherwise people will be able to attack the blockchain and rewrite history). So if a cryptocurrency fails and its value collapses then suddenly your proofs become worthless as a side effect.
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Smart contracts can’t even do anything interesting without a trusted source of data input. ...for a certain definition of "doing anything interesting", just as well as "trusted source"*. As the locus of economy shifts more and more away from physical widgets and into information, the value of information goes up in relation to physical widgets. This makes Blockchain a practical, if not all-encompassing, tool for veri…
> Proving I had certain information at certain time point The blockchain solves the problem of proving ownership of a transferable asset. If you just want to prove that you have certain information at a certain time point there are much simpler solutions: Publicly release the hash of a message (let's say: "I created this using the licence key XXX-XXX-XXX" + signature from your private key) on Twitter/Facebook/Github/…
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> What defines a blockchain for you? A (potentially distributed) datastructure of some kind, which resembles a linked-list, and ensures its integrity using some sort of cryptographic hash of the previous link such that changing any link but the most recent invalidates the whole chain. Literally -- a chain of (data) blocks. A non-engineering description of a "blockchain" should be considered to be misleading. edit - a…
Is utterly funny to read people's opinions bashing against blockchain technology and when asked about a simple definition they fail to mention the use of consensus protocols which was, already 10 years ago, the huge innovation that lead to this revolution.