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Bitcoin => Development & Technical Discussion => Topic started by: Vaunakiller on October 23, 2018, 01:22:10 PM



Title: Is it possible to intentionally not submit a share that solves the block?
Post by: Vaunakiller on October 23, 2018, 01:22:10 PM
Imagine a mining pool with PPS payout scheme.
Is it possible for a miner to intentionally not submit a share that solves a block to the pool? Thus, if one has enough hashrate (for example, 50% of pool's hashrate), he can hinder pool's ability to solve blocks by 50% and harm the pool owners because one still getting paid for all submitted shares.
Am I right or I missing something here?


Title: Re: Is it possible to intentionally not submit a share that solves the block?
Post by: Remember remember the 5th of November on October 23, 2018, 09:59:43 PM
Yes, block withholding is possible, but people with 50% of the hash power do not mine in pools, they are the pool. Not sure how it is now, but generally in the past it was possible for someone with >51% of the hashpower to mine blocks and not broadcast them immediately then after a while, spend his coins on exchanges, afterwards releasing his mined blocks to the network thus double spending.


Title: Re: Is it possible to intentionally not submit a share that solves the block?
Post by: aleksej996 on October 23, 2018, 11:01:15 PM
Yes, this should be possible, but you really can't gain nothing from it.
Any effort that you spend in setting this up is better spent anywhere else, unless you simply don't like mining for pools due to centralization issues and still want to be in a Bitcoin mining business.


Title: Re: Is it possible to intentionally not submit a share that solves the block?
Post by: gmaxwell on October 24, 2018, 12:50:20 AM
https://bitcoin.stackexchange.com/questions/4943/what-is-a-block-withholding-attack

It's even possible to profit from it if you have a large percentage of the network hashpower: This works by combining withholding at a PPS pool (to lower the network difficulty while still getting paid) and solo mining.



Title: Re: Is it possible to intentionally not submit a share that solves the block?
Post by: Thirdspace on October 24, 2018, 11:48:34 AM
... harm the pool owners because one still getting paid for all submitted shares.
Am I right or I missing something here?
they won't get paid, pool owner pays shares (distributes block reward) only when a block found
if someone not submitting solved block, then there's nothing to distribute to pool members
the harm is that pool loses its chance to earn that block reward
though I'm curious... can a pool member broadcast the solved block as his own to claim full reward for himself?


Title: Re: Is it possible to intentionally not submit a share that solves the block?
Post by: bob123 on October 24, 2018, 12:02:43 PM
though I'm curious... can a pool member broadcast the solved block as his own to claim full reward for himself?

No, he can't.

The block is being built by the pool operator. The share a miner (inside of the pool) is working on has the block reward (to the operators address) already included.
So, effectively you can not contribute to the pool while on the same time trying to mine for yourself.


Title: Re: Is it possible to intentionally not submit a share that solves the block?
Post by: aliashraf on October 24, 2018, 01:25:46 PM
Block withholding attack is detectable in serious cases where attacker has a considerable power. Being a trusted party the pool operator can suspend miner payment for a while as a counter measure. I suppose pools constantly monitor their workers' statistics for this.