3 ms·

> A blockchain, put simply, is a way of building distributed consensus in a trustless system. How different is a blockchain from https://en.wikipedia.org/wiki/

> A blockchain, put simply, is a way of building distributed consensus in a trustless system. How different is a blockchain from https://en.wikipedia.org/wiki/Mainline_DHT https://en.wikipedia.org/wiki/Mainline_DHT? edit: https://stackoverflow.com/questions/26415908/whats-the-difference-between-distributed-hashtable-technology-and-the-bitcoin-b https://stackoverflow.com/questions/26415908/whats-the-diffe...

zamadatix 5y ago
DHT doesn't build a consensus, most blatantly because nodes don't even have the full set of information but also because if they did they aren't validating it anyways. About the only similarities are they are distributed systems to share data that utilize cryptography in some way.
- MuffinFlavored 5y ago
  What does "build a consensus" mean in the context of blockchain? Consensus of... whether or not the messages are correctly cryptographically signed?
  - aforwardslash 5y ago
    It means that if you fetch an update to your DHT from a node, you don't validate if that node actually has the reputation for pushing that update, and the update itself may contain spurious data that eg. rewrites part of already existing data. This is important when your data is somehow updated and/or when you append more data to a given context, hence the typical tree data structure and not a hash table.
    - MuffinFlavored 5y ago
      i feel like most blockchains are just used for pushing data: i want to send money somewhere pulling data: so and so (sometimes myself) has received money you get a list of nodes by DNS resolving seed.bitcoin.sipa.be then you connect at port 8333 and speak the "BTC" protocol or whatever and either listen for a bunch of data, or push your own data (like a transaction) where is the validation part that you are referring to?
      - zamadatix 5y ago
        Blockchain cryptographically stores that transaction in the state of the blockchain (hence it being a chain) for the rest of time. With DHT you can exchange info between nodes but nobody else is validating the data and when the nodes go offline the data disappears.
        MuffinFlavored 5y ago
        How does that work with exchanges like Coinbase? In order to validate their transactions, you have to walk back a ton of transactions?
  - ynik 5y ago
    Consensus of the order of transactions. A could sign two messages: "I, A, send my bitcoin to B" and "I, A, send my bitcoin to C". There needs to be global consensus whether the bitcoin ends up with B or C, otherwise the coin would be effectively duplicated and it wouldn't work as money. And further messages that A might sign in the future should not be able to retroactively change the recipient -- e.g. if we used a rule "the first recipient in alphabetical order wins", then A could take back the money months later by signing "I send my bitcoin to myself". So bitcoin instead uses "the first transaction to be put into a mined block wins", and thus needs a global consensus for the order of mined blocks.

zamadatix 5y ago

DHT doesn't build a consensus, most blatantly because nodes don't even have the full set of information but also because if they did they aren't validating it anyways. About the only similarities are they are distributed systems to share data that utilize cryptography in some way.

MuffinFlavored 5y ago
What does "build a consensus" mean in the context of blockchain? Consensus of... whether or not the messages are correctly cryptographically signed?
- aforwardslash 5y ago
  It means that if you fetch an update to your DHT from a node, you don't validate if that node actually has the reputation for pushing that update, and the update itself may contain spurious data that eg. rewrites part of already existing data. This is important when your data is somehow updated and/or when you append more data to a given context, hence the typical tree data structure and not a hash table.
  - MuffinFlavored 5y ago
    i feel like most blockchains are just used for pushing data: i want to send money somewhere pulling data: so and so (sometimes myself) has received money you get a list of nodes by DNS resolving seed.bitcoin.sipa.be then you connect at port 8333 and speak the "BTC" protocol or whatever and either listen for a bunch of data, or push your own data (like a transaction) where is the validation part that you are referring to?
    - zamadatix 5y ago
      Blockchain cryptographically stores that transaction in the state of the blockchain (hence it being a chain) for the rest of time. With DHT you can exchange info between nodes but nobody else is validating the data and when the nodes go offline the data disappears.
      - MuffinFlavored 5y ago
        How does that work with exchanges like Coinbase? In order to validate their transactions, you have to walk back a ton of transactions?
- ynik 5y ago
  Consensus of the order of transactions. A could sign two messages: "I, A, send my bitcoin to B" and "I, A, send my bitcoin to C". There needs to be global consensus whether the bitcoin ends up with B or C, otherwise the coin would be effectively duplicated and it wouldn't work as money. And further messages that A might sign in the future should not be able to retroactively change the recipient -- e.g. if we used a rule "the first recipient in alphabetical order wins", then A could take back the money months later by signing "I send my bitcoin to myself". So bitcoin instead uses "the first transaction to be put into a mined block wins", and thus needs a global consensus for the order of mined blocks.