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> The only necessary assumption is that 51% of the hash power is not conspiring against you. Or s network operator , to be pedantic.
by kobeya 10y ago
> The only necessary assumption is that 51% of the hash power is not conspiring against you.
Or s network operator , to be pedantic.
- modeless 10y agoI'm not sure what you intend to mean. If you intend to mean that you must trust your ISP, that is false. ISPs cannot forge blocks due to the proof of work. The worst your ISP can do is a DoS attack delaying block delivery, and that is fairly easy to detect.
- kobeya 10y agoYou can end up on a less work chain because your ISP filtered all connections to the real bitcoin network and you only connected to Sybil nodes. You never hear about the real blocks, just the handful of blocks mined by the attacker.
- modeless 10y agoNo matter what your ISP does you can still verify the proof of work. So your ISP's forged blocks still need the full difficulty PoW that the real chain had at the fork point. Which means that in order to generate a forged block more often than once a day, your ISP will need a significant fraction of the hash power of the whole network, costing probably tens of millions of dollars to buy and operate. Even so the forged blocks will come much, much slower than the real blocks, and that will become noticeable after just a few blocks.
- kobeya 10y agoSignificant? No it only takes a few percent of the hashrate to make a few blocks to successfully Sybil an infrequently connected SPV node, or a full node that has been partitioned off for which you have sufficient time to prepare the alternate chain. You're not outracing the network, just making sure the victim doesn't have a view into the real network.