8 ms·

No it would not. Finding a BTC double spend attack vector would be like finding a 0-day: good and maybe even profitable up until fixed, which would take hours,

by vntok 8y ago

No it would not. Finding a BTC double spend attack vector would be like finding a 0-day: good and maybe even profitable up until fixed, which would take hours, days at most. Have 0-days destroyed Microsoft, Android, Firefox, Electron or Chrome?

alttab 8y ago
So it's ok if your currency becomes unreliable for many hours? It would immediately negate the trust of what happened during that period of time, affecting the trust of any balance in participating addresses.
- vntok 8y ago
  If Visa or SEPA got hacked over 12 hours and then fixed the root cause, would you stop using credit cards or bank transfers altogether? I would not.
  - djsumdog 8y ago
    Credit Card companies and banks can reverse the transactions, so long as they keep track of things in batches, have strong backup system for their ledgers. So long as they're not SWIFT transactions that leave the country, and the country that's attacked as a strong/regulated inter-bank transfer system. If a bank is critically hit so bad funds become impossible to correctly attribute to people (Fight Club type unrealistic scenario), at least in the US FDIC would probably come in to play. The bank might even have to be treated as a failed bank. People wouldn't stop using banks, but they would stop using that bank.
    - eric-hu 8y ago
      > People wouldn't stop using banks, but they would stop using that bank. I'd really like to live in a world where that's true, but I don't see Equifax going anywhere. PayPal does a form of this as well, except it's the central system and not a rogue actor that locks your money away. Well informed users avoid PayPal, but there appear to be many more uninformed users.
  - XorNot 8y ago
    Neither of those things "are money" and they're all highly reversible. A major hack against Visa would absolutely tank the value of Visa the company however, and if people who believed they were paid weren't made whole somehow then it would also tank the acceptance of Visa. And it would be an ongoing devaluation without Visa being able to show they'd fixed the underlying flaw - which you can't with a 51% attack.
  - user9182031 8y ago
    My credit card gets stolen yearly. Sure, they can reverse the charges but changing the number everywhere is annoying..
- 384243423 8y ago
  We still use USD after 2008.
- doorbumper 8y ago
  Bitcoin hasn't been useful as a currency for a long time. I don't think that's a good measure for determining how an event might affect bitcoin price.
  - robertAngst 8y ago
    speak for yourself, only thing I cant pay is my mortgage. I have a shift card, bought tacobell with bitcoin.
    - jjeaff 8y ago
      That's not buying anything with Bitcoin. You are converting your Bitcoin to USD and then purchasing using the traditional, centrally controlled financial system. And that's not even considering the transactions fees it costs to get the Bitcoin to your account. Then there are the transaction fees for using the card, which coinbase says is free "for now".
      - brownbat 8y ago
        That's like saying you can't buy anything with a VISA. Sure, transactions are intermediated through some consensus denomination for exchange. So? He still lost bitcoin and gained tacos. Just as someone else might lose a portion of a credit balance and gain tacos. You get just as full either way.
        wpietri 8y ago
        It's more like saying you can't buy anything with gold. Credit and debit cards are just a way of shifting dollars around. Bitcoin is more a commodity than a currency. Yes, you can convert gold or oil to dollars and buy things, but you can't walk into a store and give them some gold flake or a quart of Texas crude in exchange for a candy bar.
        brownbat 8y ago
        > Credit and debit cards are just a way of shifting dollars around A credit card is shifting a line of credit, an intangible promise to pay, a form of trust, that happens to be denominated in dollars. We can pretend it's just a balance of dollars, even though it technically isn't, because it makes conversations easier, and in practical fact that's how it appears to work. But that's just a shorthand. We can use the same shorthand to say someone bought something with bitcoin. There's no reason to demand perfect technical precision with bitcoin and no similar pedantic precision with lines of credit. > you can't walk into a store and give them some gold flake or a quart of Texas crude in exchange for a candy bar I think this is the best test. Here the guy has done that. He walked in with bitcoin and walked out with tacos. When you say that's not really what happened, it feels like a no true scotsman response.
- EpicEng 8y ago
  This has already happened multiple times to BTC and it's still around. BTC is not a currency; that train left long ago.
  - robertAngst 8y ago
    I dont think it has?
    - IncRnd 8y ago
      You don't think what has? There have been double spend attacks against BTC.
      - Jommi 8y ago
        source?
        zeven7 8y ago
        Not exactly a double spend, but billions BTC being printed out of thin air: https://bitcointalk.org/index.php?topic=822.0 https://bitcointalk.org/index.php?topic=822.0
        celticninja 8y ago
        It has happened before but that was in 2010 when the codebase was < 2 years old.
        IncRnd 8y ago
        It's happened quite a few times after that. Consider the merchants who have been known to use fewer than the standard # of confirmations and what it takes to reverse or reuse those charges. For example, here is a blog post on one way to do this: https://blog.acolyer.org/2015/10/01/misbehavior-in-bitcoin-a-study-of-double-spending-and-accountability/ https://blog.acolyer.org/2015/10/01/misbehavior-in-bitcoin-a.... If you want to search you will find that there are scripts to automate this type of action by constructing bitcoin transactions. Also, consider ghash.io or the odd OKPAY double spends.
bdonlan 8y ago
Don't underestimate how long it takes to deploy a fix to such a vulnerability. Any change in consensus (which this would be) is a hard fork, and deploying it without carefully coordinating months in advance is certain to cause chaos.
busterarm 8y ago
Microsoft, Android, Firefox, Electron and Chrome aren't currencies. They have an underlying value/utility. People have a real, tangible need _outside of the use of those products_ to get them fixed. Can you say the same for a cryptocurrency?
- Jommi 8y ago
  yes?
  - Ygg2 8y ago
    What is the value of currency you can legally print on any printer? Zero. Edit: any crypto-currency you can exploit gives you option to print yourself money.
    - Jommi 8y ago
      You're over reducing things to the point where they don't make sense anymore lol First of all, the value of a currency that could be printer on any printer might not actually be even 0. Secondly, cryptocurrencies do not operate in vacuum. Its not as simple as "printing yourself money".
      - Ygg2 8y ago
        Right, it could possibly be negative. Second, if I went to a store spent 199 dollars and those 199 dollars magically reappeared in my hand, didn't I create money out of nothing and reduce dollar value? Yes I did. Even if I never cloned any money I reduce the expectations of future stores that their money won't magically disappear. And yes, I am aware banks do this, but they are regulated and when they abuse it, you get a financial crisis.
    - erikpukinskis 8y ago
      Double spend isn’t like printing money on a printer. It’s more like being able to write two checks for your whole bank balance and having them both clear. So very relevant are: - whatever goods you bought with the checks need to be impossible to recall. So, like you need to find (two) someone’s who will effectively cash your check. You can’t buy a house because the police will come take the house back. - you need to do it fast. The second you make are the first transaction you need fork and start mining hard. 51% gives you a speed advantage, but it’s very small. It still takes time to get the network to follow you. Double spend is a very specific heist. Even if someone did it, it wouldn’t mean Bitcoin is valueless, it would just mean a certain class of heist is somewhat more probably and people need to adjust their security practices accordingly. Tricks like waiting for extra confirmations, requiring identification before accepting payment, etc, are easy remediations.
oh_sigh 8y ago
Why do you think a double-spend attack would be easy to figure out? It could rely on start of the art crypto attacks which aren't known to the general public, or some very obscure bug which has slipped past thousands of eyeballs.

by vntok 8y ago

alttab 8y ago

So it's ok if your currency becomes unreliable for many hours? It would immediately negate the trust of what happened during that period of time, affecting the trust of any balance in participating addresses.

vntok 8y ago
If Visa or SEPA got hacked over 12 hours and then fixed the root cause, would you stop using credit cards or bank transfers altogether? I would not.
- djsumdog 8y ago
  Credit Card companies and banks can reverse the transactions, so long as they keep track of things in batches, have strong backup system for their ledgers. So long as they're not SWIFT transactions that leave the country, and the country that's attacked as a strong/regulated inter-bank transfer system. If a bank is critically hit so bad funds become impossible to correctly attribute to people (Fight Club type unrealistic scenario), at least in the US FDIC would probably come in to play. The bank might even have to be treated as a failed bank. People wouldn't stop using banks, but they would stop using that bank.
  - eric-hu 8y ago
    > People wouldn't stop using banks, but they would stop using that bank. I'd really like to live in a world where that's true, but I don't see Equifax going anywhere. PayPal does a form of this as well, except it's the central system and not a rogue actor that locks your money away. Well informed users avoid PayPal, but there appear to be many more uninformed users.
- XorNot 8y ago
  Neither of those things "are money" and they're all highly reversible. A major hack against Visa would absolutely tank the value of Visa the company however, and if people who believed they were paid weren't made whole somehow then it would also tank the acceptance of Visa. And it would be an ongoing devaluation without Visa being able to show they'd fixed the underlying flaw - which you can't with a 51% attack.
- user9182031 8y ago
  My credit card gets stolen yearly. Sure, they can reverse the charges but changing the number everywhere is annoying..
384243423 8y ago
We still use USD after 2008.
doorbumper 8y ago
Bitcoin hasn't been useful as a currency for a long time. I don't think that's a good measure for determining how an event might affect bitcoin price.
- robertAngst 8y ago
  speak for yourself, only thing I cant pay is my mortgage. I have a shift card, bought tacobell with bitcoin.
  - jjeaff 8y ago
    That's not buying anything with Bitcoin. You are converting your Bitcoin to USD and then purchasing using the traditional, centrally controlled financial system. And that's not even considering the transactions fees it costs to get the Bitcoin to your account. Then there are the transaction fees for using the card, which coinbase says is free "for now".
    - brownbat 8y ago
      That's like saying you can't buy anything with a VISA. Sure, transactions are intermediated through some consensus denomination for exchange. So? He still lost bitcoin and gained tacos. Just as someone else might lose a portion of a credit balance and gain tacos. You get just as full either way.
      - wpietri 8y ago
        It's more like saying you can't buy anything with gold. Credit and debit cards are just a way of shifting dollars around. Bitcoin is more a commodity than a currency. Yes, you can convert gold or oil to dollars and buy things, but you can't walk into a store and give them some gold flake or a quart of Texas crude in exchange for a candy bar.
        brownbat 8y ago
        > Credit and debit cards are just a way of shifting dollars around A credit card is shifting a line of credit, an intangible promise to pay, a form of trust, that happens to be denominated in dollars. We can pretend it's just a balance of dollars, even though it technically isn't, because it makes conversations easier, and in practical fact that's how it appears to work. But that's just a shorthand. We can use the same shorthand to say someone bought something with bitcoin. There's no reason to demand perfect technical precision with bitcoin and no similar pedantic precision with lines of credit. > you can't walk into a store and give them some gold flake or a quart of Texas crude in exchange for a candy bar I think this is the best test. Here the guy has done that. He walked in with bitcoin and walked out with tacos. When you say that's not really what happened, it feels like a no true scotsman response.
EpicEng 8y ago
This has already happened multiple times to BTC and it's still around. BTC is not a currency; that train left long ago.
- robertAngst 8y ago
  I dont think it has?
  - IncRnd 8y ago
    You don't think what has? There have been double spend attacks against BTC.
    - Jommi 8y ago
      source?
      - zeven7 8y ago
        Not exactly a double spend, but billions BTC being printed out of thin air: https://bitcointalk.org/index.php?topic=822.0 https://bitcointalk.org/index.php?topic=822.0
        celticninja 8y ago
        It has happened before but that was in 2010 when the codebase was < 2 years old.
        IncRnd 8y ago
        It's happened quite a few times after that. Consider the merchants who have been known to use fewer than the standard # of confirmations and what it takes to reverse or reuse those charges. For example, here is a blog post on one way to do this: https://blog.acolyer.org/2015/10/01/misbehavior-in-bitcoin-a-study-of-double-spending-and-accountability/ https://blog.acolyer.org/2015/10/01/misbehavior-in-bitcoin-a.... If you want to search you will find that there are scripts to automate this type of action by constructing bitcoin transactions. Also, consider ghash.io or the odd OKPAY double spends.

bdonlan 8y ago

Don't underestimate how long it takes to deploy a fix to such a vulnerability. Any change in consensus (which this would be) is a hard fork, and deploying it without carefully coordinating months in advance is certain to cause chaos.

busterarm 8y ago

Microsoft, Android, Firefox, Electron and Chrome aren't currencies. They have an underlying value/utility. People have a real, tangible need _outside of the use of those products_ to get them fixed. Can you say the same for a cryptocurrency?

Jommi 8y ago
yes?
- Ygg2 8y ago
  What is the value of currency you can legally print on any printer? Zero. Edit: any crypto-currency you can exploit gives you option to print yourself money.
  - Jommi 8y ago
    You're over reducing things to the point where they don't make sense anymore lol First of all, the value of a currency that could be printer on any printer might not actually be even 0. Secondly, cryptocurrencies do not operate in vacuum. Its not as simple as "printing yourself money".
    - Ygg2 8y ago
      Right, it could possibly be negative. Second, if I went to a store spent 199 dollars and those 199 dollars magically reappeared in my hand, didn't I create money out of nothing and reduce dollar value? Yes I did. Even if I never cloned any money I reduce the expectations of future stores that their money won't magically disappear. And yes, I am aware banks do this, but they are regulated and when they abuse it, you get a financial crisis.
  - erikpukinskis 8y ago
    Double spend isn’t like printing money on a printer. It’s more like being able to write two checks for your whole bank balance and having them both clear. So very relevant are: - whatever goods you bought with the checks need to be impossible to recall. So, like you need to find (two) someone’s who will effectively cash your check. You can’t buy a house because the police will come take the house back. - you need to do it fast. The second you make are the first transaction you need fork and start mining hard. 51% gives you a speed advantage, but it’s very small. It still takes time to get the network to follow you. Double spend is a very specific heist. Even if someone did it, it wouldn’t mean Bitcoin is valueless, it would just mean a certain class of heist is somewhat more probably and people need to adjust their security practices accordingly. Tricks like waiting for extra confirmations, requiring identification before accepting payment, etc, are easy remediations.

oh_sigh 8y ago

Why do you think a double-spend attack would be easy to figure out? It could rely on start of the art crypto attacks which aren't known to the general public, or some very obscure bug which has slipped past thousands of eyeballs.