5 ms·

Is it wrong, though? I’m constantly surprised how incurious Bitcoiners are about what will happen when the block reward subsidy pool runs out. I still haven’t h

by paulgb 4y ago

Is it wrong, though? I’m constantly surprised how incurious Bitcoiners are about what will happen when the block reward subsidy pool runs out. I still haven’t heard a convincing story about what will happen to the network security a few halvings from now, besides “who cares, I will have sold by then”

fezfight 4y ago
Donno! But would you take Tim Cooks opinion on Android phones? How about Elons on NASA? Gonna need a less invested source.
- paulgb 4y ago
  Honestly I’d probably learn more from hearing Tim Cook talk about iPhone vs Android, or Elon Musk talk about NASA vs SpaceX, than I would from hearing from almost any impartial observer. I’m by no means a fanboy of either, but I respect the fact that both of them have spent a bunch of their life learning about this stuff and understand it at a level I don’t. Of course I’d treat it as a biased source of information, but I’d still treat it as informative.
  - fezfight 4y ago
    How could you, a non-expert, discern what parts were bias or not? You might believe you'd learn more things, but how much of it would be spun? What is left out, glossed over, or exaggerated?
- michaelwww 4y ago
  > But would you take Tim Cooks opinion on Android phones? How about Elons on NASA I sure would. I'm always interested in what people have to say about their competition. When Steve Balmer said iPhones were a losing idea, did I believe him? No, I thought he was making a mistake, to put it politely. But it was instructive to let me know where Microsoft's mindset was at.
adastra22 4y ago
It is wrong. It is conflating two things: market cap and total vulnerable funds in a reorg. Doing a 51% attack isn't free range to steal any bitcoin, all you can do is reverse a recent transaction. And in practice it needs to be very recent (like within the last hour) to be pulled off. Let's work out an actual attack: I send 1000 btc to an exchange, let it confirm, exchange for something else (Ethereum, let's say) and withdraw. Once my ethereum withdraw is seen on that network, I start 51% attacking the bitcoin chain and unwind the dozen or so blocks that have occurred since I sent the deposit. Maybe this attack costs me 500 btc, but in doing so I get my 1000 btc back. So I effectively bought that ethereum at half price by defrauding the exchange. It needs to be a lot of currency because the 500 btc price of the reorg (made up number!) is a fixed cost, independent of the value of the transaction I'm reversing. The total market cap of bitcoin doesn't enter into this. The most value I can obtain is the lesser of (1) how much bitcoin I have, and (2) what limit the exchange places on deposits. Exchanges (or other trading partners) can put a hold or delay on high-value deposits, which completely mitigates this attack. Now the expense of the attack is dependent on the mining revenue per block. So if the mining revenue per block is $300k or so, to use a number from the article, then exchanges and other users of bitcoin should require extra confirmations for transactions > $1MM or so. I don't know about you, but I think it's perfectly acceptable to say that settling a transaction worth $500MM will require waiting for at least a day's worth of confirmations. And that's all that's required to prevent this attack from being profitable at scale.
- zeroclip 4y ago
  From what I understand, the primary mode of 51% attack is controlling 51% of hash power, such as renting a lot of GPU for a short term attack. This gives you the ability to censor the network, rendering it near useless and probably crashing the value of BTC. If the attacker has shorted BTC it may be profitable to crash the price.
- paulgb 4y ago
  I agree that a 51% attack just to reverse a transaction is unlikely, but given how disruptive it would be (as a break in an otherwise ~perfect security track record), there could be other motives. For example, someone could take a short position in Bitcoin. Or a government could attack it for any number of reasons.
hackernudes 4y ago
Well there is this famous post by Greg Maxwell where fees almost reached the block reward amount (pull out "champaign"): https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-December/015455.html https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017... As long as there is demand for block space, a market will exist. Also, block size can be increased. Bitcoin will need a hard fork anyway to fix the year 2106 problem (https://bitcointalk.org/index.php?topic=760 https://bitcointalk.org/index.php?topic=760).
- Stevvo 4y ago
  "Also, block size can be increased". Politically, no, it can't. That is the hill that "Bitcoin" has chosen to die on.
  - kybernetikos 4y ago
    That's fairly literal. There are a few ways of fixing the core problem (e.g. continued issuance, increased blocksize, proof of stake) but bitcoin political ossification makes it look more likely the chain will die rather than make the necessary changes.
    - aaaaaaaaata 4y ago
      Other forks have done it. They've already chosen, no?
- ETH_start 4y ago
  Fees have come down significantly since the Maxwell post, and haven't returned to that level since. Hence the problem. >>As long as there is demand for block space, a market will exist. Of course a market exists. But the current demand will not be enough to secure the network once the subsidy sees a couple halvings. >>Also, block size can be increased Both a block size increase and raising the 21 million coin limit are unacceptable according to Bitcoin's current leadership.
vbezhenar 4y ago
It’s a market. It’ll adjust itself.

by paulgb 4y ago

fezfight 4y ago

Donno! But would you take Tim Cooks opinion on Android phones? How about Elons on NASA? Gonna need a less invested source.

paulgb 4y ago
Honestly I’d probably learn more from hearing Tim Cook talk about iPhone vs Android, or Elon Musk talk about NASA vs SpaceX, than I would from hearing from almost any impartial observer. I’m by no means a fanboy of either, but I respect the fact that both of them have spent a bunch of their life learning about this stuff and understand it at a level I don’t. Of course I’d treat it as a biased source of information, but I’d still treat it as informative.
- fezfight 4y ago
  How could you, a non-expert, discern what parts were bias or not? You might believe you'd learn more things, but how much of it would be spun? What is left out, glossed over, or exaggerated?
michaelwww 4y ago
> But would you take Tim Cooks opinion on Android phones? How about Elons on NASA I sure would. I'm always interested in what people have to say about their competition. When Steve Balmer said iPhones were a losing idea, did I believe him? No, I thought he was making a mistake, to put it politely. But it was instructive to let me know where Microsoft's mindset was at.

adastra22 4y ago

It is wrong. It is conflating two things: market cap and total vulnerable funds in a reorg. Doing a 51% attack isn't free range to steal any bitcoin, all you can do is reverse a recent transaction. And in practice it needs to be very recent (like within the last hour) to be pulled off. Let's work out an actual attack: I send 1000 btc to an exchange, let it confirm, exchange for something else (Ethereum, let's say) and withdraw. Once my ethereum withdraw is seen on that network, I start 51% attacking the bitcoin chain and unwind the dozen or so blocks that have occurred since I sent the deposit. Maybe this attack costs me 500 btc, but in doing so I get my 1000 btc back. So I effectively bought that ethereum at half price by defrauding the exchange. It needs to be a lot of currency because the 500 btc price of the reorg (made up number!) is a fixed cost, independent of the value of the transaction I'm reversing. The total market cap of bitcoin doesn't enter into this. The most value I can obtain is the lesser of (1) how much bitcoin I have, and (2) what limit the exchange places on deposits. Exchanges (or other trading partners) can put a hold or delay on high-value deposits, which completely mitigates this attack. Now the expense of the attack is dependent on the mining revenue per block. So if the mining revenue per block is $300k or so, to use a number from the article, then exchanges and other users of bitcoin should require extra confirmations for transactions > $1MM or so. I don't know about you, but I think it's perfectly acceptable to say that settling a transaction worth $500MM will require waiting for at least a day's worth of confirmations. And that's all that's required to prevent this attack from being profitable at scale.

zeroclip 4y ago
From what I understand, the primary mode of 51% attack is controlling 51% of hash power, such as renting a lot of GPU for a short term attack. This gives you the ability to censor the network, rendering it near useless and probably crashing the value of BTC. If the attacker has shorted BTC it may be profitable to crash the price.
paulgb 4y ago
I agree that a 51% attack just to reverse a transaction is unlikely, but given how disruptive it would be (as a break in an otherwise ~perfect security track record), there could be other motives. For example, someone could take a short position in Bitcoin. Or a government could attack it for any number of reasons.

hackernudes 4y ago

Well there is this famous post by Greg Maxwell where fees almost reached the block reward amount (pull out "champaign"): https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-December/015455.html https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017... As long as there is demand for block space, a market will exist. Also, block size can be increased. Bitcoin will need a hard fork anyway to fix the year 2106 problem (https://bitcointalk.org/index.php?topic=760 https://bitcointalk.org/index.php?topic=760).

Stevvo 4y ago
"Also, block size can be increased". Politically, no, it can't. That is the hill that "Bitcoin" has chosen to die on.
- kybernetikos 4y ago
  That's fairly literal. There are a few ways of fixing the core problem (e.g. continued issuance, increased blocksize, proof of stake) but bitcoin political ossification makes it look more likely the chain will die rather than make the necessary changes.
  - aaaaaaaaata 4y ago
    Other forks have done it. They've already chosen, no?
ETH_start 4y ago
Fees have come down significantly since the Maxwell post, and haven't returned to that level since. Hence the problem. >>As long as there is demand for block space, a market will exist. Of course a market exists. But the current demand will not be enough to secure the network once the subsidy sees a couple halvings. >>Also, block size can be increased Both a block size increase and raising the 21 million coin limit are unacceptable according to Bitcoin's current leadership.

vbezhenar 4y ago

It’s a market. It’ll adjust itself.