Author: Chris Priest 2015-12-20 03:34:26
Published on: 2015-12-20T03:34:26+00:00
During the Scaling Bitcoin conference in Hong Kong, a workshop session was held where pools representing a super majority of the Bitcoin hashing power discussed block withholding attacks. Pools are facing legitimate threats from bad actors who are threatening to use block withholding attacks against them. The decentralization of hashing power is at risk as pools without anti-privacy KYC have little defense against such attacks. P2Pool is often suggested as a replacement for pools but it too is vulnerable to block withholding and has other vulnerabilities preventing widespread adoption.Block withholding is relatively simple to fix, but it requires a SPV-visible hardfork. Luke-Jr's two-stage target mechanism can be used to fix this issue. This hard-fork should coincide with any blocksize increase to show consent by the entire ecosystem, including SPV clients.Ittay Eyal and Emin Gun Sirer have argued that block withholding attacks can be used by small pools against larger pools, disincentivizing large pools. However, in the real world, this argument is not applicable as anti-privacy KYC combined with the legal system and variety of withholding detection mechanisms are practical for large pools. Large hashing power installations, which can be dangerous for decentralization, have no block withholding attack vulnerabilities.Currently, block withholding attacks are only theoretical as those with all the hashpower today are not engaging in this behavior. Even if someone with a lot of hashpower decided to pull off this attack, they wouldn't be able to disrupt much. Therefore, until this becomes an actual problem, it should be a low priority as there are more important things to work on in the meantime.
Updated on: 2023-06-11T02:30:46.025211+00:00