{"type":"rich","version":"1.0","author_name":"npub18df3zgqr9zt5ah42zpd34rmq6fp7v57vvwmtk20krhrfdczp38ks5xccej","author_url":"https://nostr.ae/npub18df3zgqr9zt5ah42zpd34rmq6fp7v57vvwmtk20krhrfdczp38ks5xccej","provider_name":"njump","provider_url":"https://nostr.ae","html":"📅 Original date posted:2015-12-20\n📝 Original message:Block witholding attacks are only possible if you have a majority of\nhashpower. If you only have 20% hashpower, you can't do this attack.\nCurrently, this attack is only a theoretical attack, as the ones with\nall the hashpower today are not engaging in this behavior. Even if\nsomeone who had a lot of hashpower decided to pull off this attack,\nthey wouldn't be able to disrupt much. Once that time comes, then I\nthink this problem should be solved, until then it should be a low\npriority. There are more important things to work on in the meantime.\n\nOn 12/19/15, Peter Todd via bitcoin-dev\n\u003cbitcoin-dev at lists.linuxfoundation.org\u003e wrote:\n\u003e At the recent Scaling Bitcoin conference in Hong Kong we had a chatham\n\u003e house rules workshop session attending by representitives of a super\n\u003e majority of the Bitcoin hashing power.\n\u003e\n\u003e One of the issues raised by the pools present was block withholding\n\u003e attacks, which they said are a real issue for them. In particular, pools\n\u003e are receiving legitimate threats by bad actors threatening to use block\n\u003e withholding attacks against them. Pools offering their services to the\n\u003e general public without anti-privacy Know-Your-Customer have little\n\u003e defense against such attacks, which in turn is a threat to the\n\u003e decentralization of hashing power: without pools only fairly large\n\u003e hashing power installations are profitable as variance is a very real\n\u003e business expense. P2Pool is often brought up as a replacement for pools,\n\u003e but it itself is still relatively vulnerable to block withholding, and\n\u003e in any case has many other vulnerabilities and technical issues that has\n\u003e prevented widespread adoption of P2Pool.\n\u003e\n\u003e Fixing block withholding is relatively simple, but (so far) requires a\n\u003e SPV-visible hardfork. (Luke-Jr's two-stage target mechanism) We should\n\u003e do this hard-fork in conjunction with any blocksize increase, which will\n\u003e have the desirable side effect of clearly show consent by the entire\n\u003e ecosystem, SPV clients included.\n\u003e\n\u003e\n\u003e Note that Ittay Eyal and Emin Gun Sirer have argued(1) that block\n\u003e witholding attacks are a good thing, as in their model they can be used\n\u003e by small pools against larger pools, disincentivising large pools.\n\u003e However this argument is academic and not applicable to the real world,\n\u003e as a much simpler defense against block withholding attacks is to use\n\u003e anti-privacy KYC and the legal system combined with the variety of\n\u003e withholding detection mechanisms only practical for large pools.\n\u003e Equally, large hashing power installations - a dangerous thing for\n\u003e decentralization - have no block withholding attack vulnerabilities.\n\u003e\n\u003e 1) http://hackingdistributed.com/2014/12/03/the-miners-dilemma/\n\u003e\n\u003e --\n\u003e 'peter'[:-1]@petertodd.org\n\u003e 00000000000000000188b6321da7feae60d74c7b0becbdab3b1a0bd57f10947d\n\u003e"}