4 ms·

A smaller blockchain might seem like a toddler compared to the big old bitcoin, however you shouldn't dismiss that the biggest shitcoins in market capitalizatio

by knocte 8y ago

A smaller blockchain might seem like a toddler compared to the big old bitcoin, however you shouldn't dismiss that the biggest shitcoins in market capitalization have a decent amount of people invested in them. Take in account a 51% attack causes a double-spend. A double-spend targetting a transaction of a big amount costs the same as if you target a transaction of a small amount. This means that whoever performs this attack could just wait until the perfect victim comes in (think: a big transaction from/to a hotwallet of a big exchange). This, in the end, could cause a big loss to some user of the exchange (especially if the exchange doesn't take responsibility for the issue); which could mean a lot more value than a lollipop. Key takeaway from this IMO: don't invest in shitcoins, err.. altcoins sorry.

piracy1 8y ago
^ This. Also, I agree that it's fairly trivial. That is the point, I want to show people how easy it is and maybe prompt developers to implement mitigations. I also just want to talk about 51% attacks because I think they're neat.
ghayes 8y ago
You should demonstrate an effective use of double-spend in your 51% attack, since there’s a lot of FUD around what can happen with a 51% attack. As in, people may assume you can drain accounts with 51% control, as opposed to double-spend transactions that did not yet hit high confirmation counts.
- piracy1 8y ago
  " As in, people may assume you can drain accounts with 51% control" This is categorically incorrect. I'll make sure to mention that.
  - mr_the_coin 8y ago
    Of course you can drain accounts with 50% hash power or greater. And the number isn't 51%, it is actually 50%. If you have 50% of the hash power, you will be ahead exactly half the time. However, you will selfish mine and this creates an asymmetry. When you are ahead, other miners will mine off your chain, making your chain the longest. You will never mine off other published blocks, no matter how far behind you are. And no matter how far behind you are, you will eventually be greater than even at some point. Because you can start mining at any point in the past, you can erase all transactions except the genesis/first transaction. The bitcoin developers realize this so they essentially stuck the blockchain in the source code by putting 'checkpoints' in the code. This protects their coins. The developers are the actual central blockchain authority. If they changed the checkpoints, they would fork the whole chain. The chain is essentially in the source code.
stale2002 8y ago
> This, in the end, could cause a big loss to some user of the exchange Not really. If someone is worried about a double spend attack, all they have to do is require a larger number of confirmations, until they are satisfied with the amount of security, for the given value of the transaction that they are accepting. For example, if a big exchange is accepting a million dollars worth of crypto, they might want to wait a very long time, in order to be absolutely sure. If someone is instead accepting payment for coffee, they could be perfectly happy to accept more risk.

by knocte 8y ago

piracy1 8y ago

^ This. Also, I agree that it's fairly trivial. That is the point, I want to show people how easy it is and maybe prompt developers to implement mitigations. I also just want to talk about 51% attacks because I think they're neat.

ghayes 8y ago

You should demonstrate an effective use of double-spend in your 51% attack, since there’s a lot of FUD around what can happen with a 51% attack. As in, people may assume you can drain accounts with 51% control, as opposed to double-spend transactions that did not yet hit high confirmation counts.

piracy1 8y ago
" As in, people may assume you can drain accounts with 51% control" This is categorically incorrect. I'll make sure to mention that.
- mr_the_coin 8y ago
  Of course you can drain accounts with 50% hash power or greater. And the number isn't 51%, it is actually 50%. If you have 50% of the hash power, you will be ahead exactly half the time. However, you will selfish mine and this creates an asymmetry. When you are ahead, other miners will mine off your chain, making your chain the longest. You will never mine off other published blocks, no matter how far behind you are. And no matter how far behind you are, you will eventually be greater than even at some point. Because you can start mining at any point in the past, you can erase all transactions except the genesis/first transaction. The bitcoin developers realize this so they essentially stuck the blockchain in the source code by putting 'checkpoints' in the code. This protects their coins. The developers are the actual central blockchain authority. If they changed the checkpoints, they would fork the whole chain. The chain is essentially in the source code.

stale2002 8y ago

> This, in the end, could cause a big loss to some user of the exchange Not really. If someone is worried about a double spend attack, all they have to do is require a larger number of confirmations, until they are satisfied with the amount of security, for the given value of the transaction that they are accepting. For example, if a big exchange is accepting a million dollars worth of crypto, they might want to wait a very long time, in order to be absolutely sure. If someone is instead accepting payment for coffee, they could be perfectly happy to accept more risk.