5 ms·

So this is basically a blockchain, but with transactions instead of blocks, and diverging-then-converging graph instead of a linear sequence of blocks (like a r

So this is basically a blockchain, but with transactions instead of blocks, and diverging-then-converging graph instead of a linear sequence of blocks (like a real family graph instead of just one-parent-one-child families common in blockchains). Looks nice, what are the problems with the approach? (the paper only lists the benefits).

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tribler 9y ago
can this handle a trivial Sybil attack? That seems to be the drawback of a graph or DAG-based approach. -ledger scientist
- TeMPOraL 9y ago
  > ledger scientist That's a thing now? :o. Please explain :).
  - JBReefer 9y ago
    I'm not getting any results for it on DDG, might be a troll
    - _jn 9y ago
      Seems to be about someone creating massive amounts of privkeys and messing with verification (the fact that 51% attacks no longer exist in this approach make that irrelevant, however.) I'm not an expert on cryptocurrencies, but I don't see how that issue could be any more prevalent here than in "standard" (Bitcoin-style) blockchains.
      - _jn 9y ago
        To expand on that: The only way I can imagine a Sybil attack here is if someone created a massive amount of tiny transactions, and the fees required to get peers to validate them would make that approach infeasible.
      - mhluongo 9y ago
        I think the question was about "ledger scientist".
        _jn 9y ago
        ...my bad. Not sure about HN etiquette—should I delete my comments as off-topic?
        kirubakaran 9y ago
        It is okay. Deleting a comment after it has replies is worse than an honest misunderstanding.
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Jabanga 9y ago
There is no way to have a controlled release of new coins into the system. For that you need a blockchain that establishes a consensus on time transpired and on the total economic resources being contributed (which allows the share of the newly generated coins that each participant will receive in a unit of time to be proportional to the share of the total economic resources they are responsible for contributing). There is no mechanism to link cost of proof of work generated to the value being transacted. With a blockchain, scarcity of space per block leads to a fee market forming, and fees paid increasing as the value contained per transaction increases. This leads to security (proof of work) increasing in proportion to value that needs to be protected.
- jcfrei 9y ago
  > There is no mechanism to link cost of proof of work generated to the value being transacted. With a blockchain, scarcity of space per block leads to a fee market forming, and fees paid increasing as the value contained per transaction increases. This leads to security (proof of work) increasing in proportion to value that needs to be protected. My understanding of proof of work is that it's used to limit the number of new blocks which will get propagated through the network. Bitcoin automatically adjusts difficulty such that it approximately takes 10 minutes for a new block. If block creation intervals were lower it would compromise the security of the system and enable attacks with much less than 50% of the hash power.
  - flashdance 9y ago
    > If block creation intervals were lower it would compromise the security of the system and enable attacks with much less than 50% of the hash power. Not really. The odds of an attacker successfully generating a double-spending block remain the same with a lower block interval. Many alternative cryptocurrencies have far shorter blocktimes: Litecoin has 2.5min blocktimes, and ethereum is less than 30 seconds IIRC, and they don't have problems with rampant double spends. The problem with shorter blocktimes is that latency has a greater impact on mining profitability. A miner with a 600ms ping will lose ~0.1% of their revenue with a 10 minute blocktime, but will lose 2% of their revenue with a 30s blocktime. This gives miners an incentive to centralize geographically to reduce their latency. No bueno!

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[deleted]

tribler 9y ago

can this handle a trivial Sybil attack? That seems to be the drawback of a graph or DAG-based approach. -ledger scientist

TeMPOraL 9y ago
> ledger scientist That's a thing now? :o. Please explain :).
- JBReefer 9y ago
  I'm not getting any results for it on DDG, might be a troll
  - _jn 9y ago
    Seems to be about someone creating massive amounts of privkeys and messing with verification (the fact that 51% attacks no longer exist in this approach make that irrelevant, however.) I'm not an expert on cryptocurrencies, but I don't see how that issue could be any more prevalent here than in "standard" (Bitcoin-style) blockchains.
    - _jn 9y ago
      To expand on that: The only way I can imagine a Sybil attack here is if someone created a massive amount of tiny transactions, and the fees required to get peers to validate them would make that approach infeasible.
    - mhluongo 9y ago
      I think the question was about "ledger scientist".
      - _jn 9y ago
        ...my bad. Not sure about HN etiquette—should I delete my comments as off-topic?
        kirubakaran 9y ago
        It is okay. Deleting a comment after it has replies is worse than an honest misunderstanding.

deleted 9y ago

[deleted]

Jabanga 9y ago

There is no way to have a controlled release of new coins into the system. For that you need a blockchain that establishes a consensus on time transpired and on the total economic resources being contributed (which allows the share of the newly generated coins that each participant will receive in a unit of time to be proportional to the share of the total economic resources they are responsible for contributing). There is no mechanism to link cost of proof of work generated to the value being transacted. With a blockchain, scarcity of space per block leads to a fee market forming, and fees paid increasing as the value contained per transaction increases. This leads to security (proof of work) increasing in proportion to value that needs to be protected.

jcfrei 9y ago
> There is no mechanism to link cost of proof of work generated to the value being transacted. With a blockchain, scarcity of space per block leads to a fee market forming, and fees paid increasing as the value contained per transaction increases. This leads to security (proof of work) increasing in proportion to value that needs to be protected. My understanding of proof of work is that it's used to limit the number of new blocks which will get propagated through the network. Bitcoin automatically adjusts difficulty such that it approximately takes 10 minutes for a new block. If block creation intervals were lower it would compromise the security of the system and enable attacks with much less than 50% of the hash power.
- flashdance 9y ago
  > If block creation intervals were lower it would compromise the security of the system and enable attacks with much less than 50% of the hash power. Not really. The odds of an attacker successfully generating a double-spending block remain the same with a lower block interval. Many alternative cryptocurrencies have far shorter blocktimes: Litecoin has 2.5min blocktimes, and ethereum is less than 30 seconds IIRC, and they don't have problems with rampant double spends. The problem with shorter blocktimes is that latency has a greater impact on mining profitability. A miner with a 600ms ping will lose ~0.1% of their revenue with a 10 minute blocktime, but will lose 2% of their revenue with a 30s blocktime. This gives miners an incentive to centralize geographically to reduce their latency. No bueno!