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Broadly speaking blockchain only solves a singular problem: Trust. If there is some work that needs to be done between parties and you don't trust the parties i

Broadly speaking blockchain only solves a singular problem: Trust. If there is some work that needs to be done between parties and you don't trust the parties involved then you can use blockchain to do the work in a trust-less setting. This is why money has been the first and most prominent use case; people are less trusting with their own money. For a specific non-money potential use case of blockchain I would say identity services. For example, currently the internet runs based on implicitly trusting a set of root CAs (hundreds just counting the big ones!). The CAs certify that a site is what it claims to be. But if the CA becomes malicious (either through intent or hack) there are limited mechanisms for combatting this. If you decentralize the certification process you can have a trust-less system. This also works beyond CAs - any sort of identity management falls under the same principle: Credit scores, citizenship, etc

slickrick216 6y ago
Not exactly what you are talking about but unstoppable domains .crypto are pretty neat how it’s implemented. I wonder could you do CA issues certs for such domains that live on chain at a specific address or is such a concept even needed if it’s on chain.
lucb1e 6y ago
> If you decentralize the certification process you can have a trust-less system. Okay so with a bit of hand-wavey stuff I'm sure we can make a parallel where you also solve world hunger with blockchain and trustless systems where there are no centralized parties that can do bad things. But realistically, how would this work? Whose key will end up signing the TLS certificate for my website? You're not really proposing anything more concrete than "let's move CAs to a blockchain".
- dgrin91 6y ago
  You're totally right, I basically just said put a CA on a blockchain. There is a lot of handwaving in my short HN comment as I wasn't planning on writing out my full RFC here :). Here is some general thoughts I had on the matter - Placing things on a blockchain is a paradigm shift. Yes you can 'just' do it on a blockchain, but you're likely not taking full advantage of the capabilities you receive. Looking at the TLS signing example - why do we actually need to sign the TLS cert? The purpose of a CA signing a cert today is so that the CA can say a cert is what the CA saw and has not been modified. Well if we put it on a blockchain we know it cant be modified (as this is an inherent property of a blockchain). Instead of asking 'can I verify this cert with the CA pub key' I ask 'can I find this cert on the blockchain'.
  - Nursie 6y ago
    It's a proof of identity, as well, because a certificate contains much more than just a public key, it contains names of servers etc. It's the CA saying "I attest that the holder of the private key that matches this certificate has this identity". Under some schemes (see the EiDAS regulations if you have trouble to going to sleep some night soon) that also vouch for company registration numbers, company roles granted within the EU financial system etc etc. I'm not sure how (or why) you would do that with a blockchain.
johnisgood 6y ago
Only that? What about non-editable history?
- geofft 6y ago
  You can do that with a plain old hash chain without any mining of blocks. Certificate Transparency does this - each monitor adds records to their ledger and signs them, and the latest record includes a hash of all previous records (via a Merkle tree). Auditors trust any hash they see which is signed by a monitor. If they see two ledgers where one is not a subset of the other, they trust all the data in both ledgers. If this persists, they have cryptographic proof that the monitor is trying to not include some record it previously included. Git does this. Each commit object has the hash of the parent commit objects. You can walk through a commit object and see what the ancestry is. If you push to a server, it can make sure that your new history includes all the old history, and similarly, if you pull from a server, you can do the same check.
  - johnisgood 6y ago
    Yes, but he said that it only solves a singular problem, and did not mention this property of the blockchain. Blockchain provides this, does it not? I have been looking around https://github.com/google/trillian https://github.com/google/trillian, looks interesting.
    - geofft 6y ago
      I think the only meaningful definition of the term "blockchain" requires the idea of mining blocks / addressing double-spend somehow. Otherwise it's just a chain, a data structure we've had for decades. The term was introduced with Nakamoto's paper, and the insight of that paper was mining / proof-of-work, not hash chains. It is technically true that one application of blockchains is solving problems that can be solved by regular chains, just like it is technically true that one application of self-driving cars is the ability to turn off the automation and let a human drive. But if someone asks about the applications of self-driving cars and you say "Driving on the open road is fun," I think most people would not accept that as answering the question asked. (And I'm not just being pedantic: blockchains have a significant computational/environmental cost, so if you don't need the block mining feature, you will get many orders of magnitude faster performance and run many of orders of magnitude cheaper and cause fewer negative externalities if you just use a plain old hash chain.)
ayewo 6y ago
You say that: “Broadly speaking blockchain only solves a singular problem: Trust.” but there is another equally significant contribution that deserves to be acknowledged: scarcity. Bits & bytes can be cloned effortlessly by computers which is why a version of Photoshop ripped from a DVD is indistinguishable from the same version downloaded from a CDN as an iso. As long as the hashes match, you wont be able to tell apart the master copy from its 1000th copy. For money to be valuable, in addition to trust, it also needs to be scarce in the physical sense. Blockchains allow us to engender that illusion of scarcity in the digital world, otherwise it would be impossible to tell apart the binary representation of a $10,000 currency note in one computer node from counterfeits held by other nodes in a network.
- dpc_pw 6y ago
  The original poster is right. Blockchain solves distributed trust. Scarcity is a particular rule, and blockchain is solving a problem of trust in that everyone are obeying that rule. You can have a blockchain that enforces completely different rules, where scarcity don't matter. And you can have scarcity in a system where trust is not a problem (trusted central party).
- delecti 6y ago
  I would argue that scarcity doesn't matter if you have sufficient trust. It's probably fair to say that the majority of global financial transactions are digital. Practically speaking, there's not much stopping any of those institutions from incrementing a few bits here and there, except for trust. The illusion of scarcity matters, but can be maintained with trust.
jkepler 6y ago
Yes. See the ION project Microsoft has led starting - its a decentralized identity project designed as a sidechain that periodically anchors its data to bitcoin's censorship resistant blockchain. See https://techcommunity.microsoft.com/t5/identity-standards-blog/ion-booting-up-the-network/ba-p/1441552 https://techcommunity.microsoft.com/t5/identity-standards-bl..., https://identity.foundation/ https://identity.foundation/, or https://github.com/decentralized-identity/ion https://github.com/decentralized-identity/ion. If your project doesn't need decentralized trust, using 'blockchain' is simply a marketing move.
briatx 6y ago
> Broadly speaking blockchain only solves a singular problem: Trust This is only true in the cryptographic sense when talking about data on the blockchain. Blockchains do NOT solve any trust problem outside of data on the blockchain, and in real world use cases when we're not dealing with how many coins each person has in a wallet, this is the most important thing. Specifically your cryptographic tamperproof data on the blockchain is useless if you have bad actors entering garbage data. It's useless if the data on the blockchain is out of sync with state in the real world. Even in the internet commerce use case where bitcoin was supposed to take over, once the bitcoins are transferred you still have the unsolved trust issue of verifying delivery. Saying blockchains solve the trust issue in the real world is disingenuous magical thinking, and I wish people would stop doing it.

slickrick216 6y ago

Not exactly what you are talking about but unstoppable domains .crypto are pretty neat how it’s implemented. I wonder could you do CA issues certs for such domains that live on chain at a specific address or is such a concept even needed if it’s on chain.

lucb1e 6y ago

> If you decentralize the certification process you can have a trust-less system. Okay so with a bit of hand-wavey stuff I'm sure we can make a parallel where you also solve world hunger with blockchain and trustless systems where there are no centralized parties that can do bad things. But realistically, how would this work? Whose key will end up signing the TLS certificate for my website? You're not really proposing anything more concrete than "let's move CAs to a blockchain".

dgrin91 6y ago
You're totally right, I basically just said put a CA on a blockchain. There is a lot of handwaving in my short HN comment as I wasn't planning on writing out my full RFC here :). Here is some general thoughts I had on the matter - Placing things on a blockchain is a paradigm shift. Yes you can 'just' do it on a blockchain, but you're likely not taking full advantage of the capabilities you receive. Looking at the TLS signing example - why do we actually need to sign the TLS cert? The purpose of a CA signing a cert today is so that the CA can say a cert is what the CA saw and has not been modified. Well if we put it on a blockchain we know it cant be modified (as this is an inherent property of a blockchain). Instead of asking 'can I verify this cert with the CA pub key' I ask 'can I find this cert on the blockchain'.
- Nursie 6y ago
  It's a proof of identity, as well, because a certificate contains much more than just a public key, it contains names of servers etc. It's the CA saying "I attest that the holder of the private key that matches this certificate has this identity". Under some schemes (see the EiDAS regulations if you have trouble to going to sleep some night soon) that also vouch for company registration numbers, company roles granted within the EU financial system etc etc. I'm not sure how (or why) you would do that with a blockchain.

johnisgood 6y ago

Only that? What about non-editable history?

geofft 6y ago
You can do that with a plain old hash chain without any mining of blocks. Certificate Transparency does this - each monitor adds records to their ledger and signs them, and the latest record includes a hash of all previous records (via a Merkle tree). Auditors trust any hash they see which is signed by a monitor. If they see two ledgers where one is not a subset of the other, they trust all the data in both ledgers. If this persists, they have cryptographic proof that the monitor is trying to not include some record it previously included. Git does this. Each commit object has the hash of the parent commit objects. You can walk through a commit object and see what the ancestry is. If you push to a server, it can make sure that your new history includes all the old history, and similarly, if you pull from a server, you can do the same check.
- johnisgood 6y ago
  Yes, but he said that it only solves a singular problem, and did not mention this property of the blockchain. Blockchain provides this, does it not? I have been looking around https://github.com/google/trillian https://github.com/google/trillian, looks interesting.
  - geofft 6y ago
    I think the only meaningful definition of the term "blockchain" requires the idea of mining blocks / addressing double-spend somehow. Otherwise it's just a chain, a data structure we've had for decades. The term was introduced with Nakamoto's paper, and the insight of that paper was mining / proof-of-work, not hash chains. It is technically true that one application of blockchains is solving problems that can be solved by regular chains, just like it is technically true that one application of self-driving cars is the ability to turn off the automation and let a human drive. But if someone asks about the applications of self-driving cars and you say "Driving on the open road is fun," I think most people would not accept that as answering the question asked. (And I'm not just being pedantic: blockchains have a significant computational/environmental cost, so if you don't need the block mining feature, you will get many orders of magnitude faster performance and run many of orders of magnitude cheaper and cause fewer negative externalities if you just use a plain old hash chain.)

ayewo 6y ago

You say that: “Broadly speaking blockchain only solves a singular problem: Trust.” but there is another equally significant contribution that deserves to be acknowledged: scarcity. Bits & bytes can be cloned effortlessly by computers which is why a version of Photoshop ripped from a DVD is indistinguishable from the same version downloaded from a CDN as an iso. As long as the hashes match, you wont be able to tell apart the master copy from its 1000th copy. For money to be valuable, in addition to trust, it also needs to be scarce in the physical sense. Blockchains allow us to engender that illusion of scarcity in the digital world, otherwise it would be impossible to tell apart the binary representation of a $10,000 currency note in one computer node from counterfeits held by other nodes in a network.

dpc_pw 6y ago
The original poster is right. Blockchain solves distributed trust. Scarcity is a particular rule, and blockchain is solving a problem of trust in that everyone are obeying that rule. You can have a blockchain that enforces completely different rules, where scarcity don't matter. And you can have scarcity in a system where trust is not a problem (trusted central party).
delecti 6y ago
I would argue that scarcity doesn't matter if you have sufficient trust. It's probably fair to say that the majority of global financial transactions are digital. Practically speaking, there's not much stopping any of those institutions from incrementing a few bits here and there, except for trust. The illusion of scarcity matters, but can be maintained with trust.

jkepler 6y ago

Yes. See the ION project Microsoft has led starting - its a decentralized identity project designed as a sidechain that periodically anchors its data to bitcoin's censorship resistant blockchain. See https://techcommunity.microsoft.com/t5/identity-standards-blog/ion-booting-up-the-network/ba-p/1441552 https://techcommunity.microsoft.com/t5/identity-standards-bl..., https://identity.foundation/ https://identity.foundation/, or https://github.com/decentralized-identity/ion https://github.com/decentralized-identity/ion. If your project doesn't need decentralized trust, using 'blockchain' is simply a marketing move.

briatx 6y ago

> Broadly speaking blockchain only solves a singular problem: Trust This is only true in the cryptographic sense when talking about data on the blockchain. Blockchains do NOT solve any trust problem outside of data on the blockchain, and in real world use cases when we're not dealing with how many coins each person has in a wallet, this is the most important thing. Specifically your cryptographic tamperproof data on the blockchain is useless if you have bad actors entering garbage data. It's useless if the data on the blockchain is out of sync with state in the real world. Even in the internet commerce use case where bitcoin was supposed to take over, once the bitcoins are transferred you still have the unsolved trust issue of verifying delivery. Saying blockchains solve the trust issue in the real world is disingenuous magical thinking, and I wish people would stop doing it.