4 ms·

It would depend on how close the attack is to 51/49%. If it's close, the 49% chain should be able to keep ahead, making the attack take a long time and thus be

It would depend on how close the attack is to 51/49%. If it's close, the 49% chain should be able to keep ahead, making the attack take a long time and thus be very expensive... but there would be constant block reorganisations. The 51% chain is mined with 51% of the total mining power, while the 49% chain will contain 100% of the mining power (as the 49% miners are more than happy to build off the 51% chain, while the 51% miners will only building off the chain without the censored transactions). They are correct in asserting that a 51% attack to censor transaction is largely just a nuisance to the users and that all transactions should eventually end up on the longest chain (the 49%).

simiones 4y ago
Any block you are working on has a reference to the latest block in the network. So, every miner starts from scratch once a new block is added - the 49% pool doesn't have any advantage compared to the 51% pool. Each miner takes a bunch of transactions and chooses a previous block B1 to build on, then starts hashing. If some other minerB advertises a new block B2 based on B1 that includes different transactions before minerA, then minerA can throw away all the work it did, and start from scratch on B3 based on B2. But minerB will probably already be working on its own B3 - and has every chance to win again.
- jimmydorry 4y ago
  Except, that minerA can't build off block B1 because it has transactions in it that it doesn't agree with. minerB just has to keep trying to find blocks to put the censored transactions into, while minerA is fighting against the rest of the miners to outpace them. This only really becomes possible at much higher thresholds, e.g. 70/30. Meanwhile, the community will see what is happening and steps may be taken to either soft-fork or hard-fork the bad actors off the network.

simiones 4y ago

Any block you are working on has a reference to the latest block in the network. So, every miner starts from scratch once a new block is added - the 49% pool doesn't have any advantage compared to the 51% pool. Each miner takes a bunch of transactions and chooses a previous block B1 to build on, then starts hashing. If some other minerB advertises a new block B2 based on B1 that includes different transactions before minerA, then minerA can throw away all the work it did, and start from scratch on B3 based on B2. But minerB will probably already be working on its own B3 - and has every chance to win again.

jimmydorry 4y ago
Except, that minerA can't build off block B1 because it has transactions in it that it doesn't agree with. minerB just has to keep trying to find blocks to put the censored transactions into, while minerA is fighting against the rest of the miners to outpace them. This only really becomes possible at much higher thresholds, e.g. 70/30. Meanwhile, the community will see what is happening and steps may be taken to either soft-fork or hard-fork the bad actors off the network.