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That's a really cool idea, but what on earth does it have to do with blockchain? Wouldn't it work better with a trusted 3rd party centralised system? Issues I

That's a really cool idea, but what on earth does it have to do with blockchain? Wouldn't it work better with a trusted 3rd party centralised system? Issues I see: - Does every phone now need to store the entire log? Otherwise, who do you trust to give you the current state? - What prevents me faking a log? Why would people be doing constant work on the chain to prevent it?

jon_richards 8y ago
The trusted 3rd party could be maintaining a blockchain. Blockchains don't have to be decentralized, they're just a type of db that can be decentralized.
- gm-conspiracy 8y ago
  You can do proof-of-work without a blockchain and have a trusted 3rd-party entity, like hashcash... https://en.wikipedia.org/wiki/Hashcash https://en.wikipedia.org/wiki/Hashcash
  - PKop 8y ago
    That produces a currency though, which would be the reward for the work. What is the reward for doing such proof of work in the context of custody chains?
    - gm-conspiracy 8y ago
      I am assuming the value of the custody chain as a whole and its constituents. If intellectual property has value, then a hash of a particular work product could be used in a chain-of-custody for ownership of IP (transfers, licensing, etc). But, yes, if it is just for virtual kittens and their accessories, I am at a loss. Otherwise, why are you wasting compute, right?
      - deleted 8y ago
        [deleted]
- simonw 8y ago
  Do you mean the trusted third party could be maintaining a GitHub repository?
- gaius 8y ago
  A blockchain controlled by a single entity is just a really crappy database
- perl4ever 8y ago
  If you don't need a decentralized solution why does it have to be a blockchain and not an Excel spreadsheet?
dane-pgp 8y ago
The advantage of using a blockchain is that you don't have to rely on hundreds of 3rd party centralised systems (one per product type you want to track). You're not just trusting these 3rd parties to not rewrite history but trusting that they maintain their infrastructure indefinitely. With a popular blockchain there are distributed financial incentives to keep the whole system running (and honest) longer than any individual actor on the network. As for how much data the phone needs to store, I was imagining running something equivalent to an SPV client: https://bitcoin.stackexchange.com/questions/4649/what-is-an-spv-client https://bitcoin.stackexchange.com/questions/4649/what-is-an-... https://bitcoin.stackexchange.com/questions/48420/what-hardware-requirements-does-a-spv-client-have https://bitcoin.stackexchange.com/questions/48420/what-hardw... Alternatively the app can request the digitally signed proofs from the blockchain via a semi-trusted 3rd party gateway, with the advantage that you can choose your gateway at any time, and the gateway can't forge the cryptographic proofs that your client is checking for you. For example, if you buy a product from Manufacturer 1 whose web address is manufacturer1.example.com, you could visit that site and find a page with a QR code containing their public key (wallet address), which the app could scan. Once you've marked that public key as trusted, the app could check that the corresponding secret key was used to sign the data on the QR code you received on your certificate of authenticity. The tricky part is sending a transaction to the network which says "I have received the product with the following serial number...", but the QR code on the certificate could contain the secret key for a wallet which has been pre-loaded with just enough funds to send a microtransaction to the network.

jon_richards 8y ago

The trusted 3rd party could be maintaining a blockchain. Blockchains don't have to be decentralized, they're just a type of db that can be decentralized.

gm-conspiracy 8y ago
You can do proof-of-work without a blockchain and have a trusted 3rd-party entity, like hashcash... https://en.wikipedia.org/wiki/Hashcash https://en.wikipedia.org/wiki/Hashcash
- PKop 8y ago
  That produces a currency though, which would be the reward for the work. What is the reward for doing such proof of work in the context of custody chains?
  - gm-conspiracy 8y ago
    I am assuming the value of the custody chain as a whole and its constituents. If intellectual property has value, then a hash of a particular work product could be used in a chain-of-custody for ownership of IP (transfers, licensing, etc). But, yes, if it is just for virtual kittens and their accessories, I am at a loss. Otherwise, why are you wasting compute, right?
    - deleted 8y ago
      [deleted]
simonw 8y ago
Do you mean the trusted third party could be maintaining a GitHub repository?
gaius 8y ago
A blockchain controlled by a single entity is just a really crappy database
perl4ever 8y ago
If you don't need a decentralized solution why does it have to be a blockchain and not an Excel spreadsheet?

dane-pgp 8y ago

The advantage of using a blockchain is that you don't have to rely on hundreds of 3rd party centralised systems (one per product type you want to track). You're not just trusting these 3rd parties to not rewrite history but trusting that they maintain their infrastructure indefinitely. With a popular blockchain there are distributed financial incentives to keep the whole system running (and honest) longer than any individual actor on the network. As for how much data the phone needs to store, I was imagining running something equivalent to an SPV client: https://bitcoin.stackexchange.com/questions/4649/what-is-an-spv-client https://bitcoin.stackexchange.com/questions/4649/what-is-an-... https://bitcoin.stackexchange.com/questions/48420/what-hardware-requirements-does-a-spv-client-have https://bitcoin.stackexchange.com/questions/48420/what-hardw... Alternatively the app can request the digitally signed proofs from the blockchain via a semi-trusted 3rd party gateway, with the advantage that you can choose your gateway at any time, and the gateway can't forge the cryptographic proofs that your client is checking for you. For example, if you buy a product from Manufacturer 1 whose web address is manufacturer1.example.com, you could visit that site and find a page with a QR code containing their public key (wallet address), which the app could scan. Once you've marked that public key as trusted, the app could check that the corresponding secret key was used to sign the data on the QR code you received on your certificate of authenticity. The tricky part is sending a transaction to the network which says "I have received the product with the following serial number...", but the QR code on the certificate could contain the secret key for a wallet which has been pre-loaded with just enough funds to send a microtransaction to the network.