For pool mining, what exactly is a share? Ethereum Stack Exchange

Can someone please explain exactly what a share is te the setting of pool mining? I have a superficial understanding of testing random nonces to find a hash under the current difficulty. I also understand that mining pools set a custom-built lighter difficulty to target a relatively effortless to attain share difficulty (

What I don’t understand is how those shares translate to finding real blocks. Say one out of a thousand shares is a valid real fresh block. Why wouldn’t miners just submit that hash themselves, and send the surplus of the lighter shares to the pool?

I’m sure I have a fundamental misunderstanding, but can’t figure out what it is. I guess somehow the pool has some secret that it can combine w/ the submitted shares to see if that share matches a block, but that is a guess.

Any help would be greatly appreciated.

Four Answers

Lots of answers here, but none of them has actually answered the question “what is a share?”

Ter almost all mining pools, a share is a block “solution” not fairly good enough to be published spil an actual block, but still good enough that it’s truly hard to find them. This means that shares can be used to measure how much work you’re doing, but just with much finer and more consistent granularity than actual block solutions, which are far too zonderling for puny miners.

So, just spil an example, suppose that the current difficulty wasgoed Ten,000. To become valid blocks, an attempted block with a specific nonce has to be “better” than Ten,000. Te this situation, the pool might set their “share difficulty” at 100. So with each nonce you attempt, your software will check to see how “good” the difficulty of the resulting block is. Most of thesis blocks will be below 100 ter “difficulty level”, but a puny amount of them will be overheen 100 ter difficulty level (and still less than Ten,000). Thesis “better than 100 but still less than Ten,000” blocks are the ones wij’re calling the “shares”. They can be sent into the mining pool, even however they aren’t good enough to be published on the open network spil actual blocks. Inwards thesis shares the mining pool will be clearly marked spil the recipient of any potential block prize, which means that the mining pool can use the number of shares you submit spil unfakeable evidence of how much work your machine is doing to attempt and find blocks for the pool, even if you’ve never found one yet. Which is good, because it takes forever to find actual blocks.

Spil you mine along, cheerfully submitting shares, then every once te blue moon you will come across a solution that is not only good enough to be a share, it’s actually good enough to be a real block! That is, it has difficulty “overheen Ten,000” and so it meets not just the share criteria but the total network standard of difficulty, which is much firmer. This one you would still submit to the pool, but when they get it they will go ahead and publish it out overheen the actual network, receiving a nice fat prize that gets distributed amongst everyone according to the shares they’ve bot submitting. Of course, thesis aren’t real numbers, and most software works by just telling your machine to look for blocks overheen 100 and not worry about what the network difficulty is. But still, wij can see how someone who isn’t doing actual mining would never be able to find any shares ter the very first place, which means this is actually reasonably secure from the pool’s perspective spil a way of measuring how much work everyone is doing.

I’ve glossed overheen a lotsbestemming of details here, because there are some subtle tricks the pool needs to be careful of (block withholding attacks anyone?), but that ter a nutshell is what shares actually are: totally normal blocks that don’t meet the utter requirements to be published on the network, but still meet some smaller requirement set by the pool to count spil proof you’re mining with the pool set spil the recipient.

Now, why can’t the miner just submit any actual blocks themselves to take the entire prize? Two reasons: very first, te order for their shares to be valid they have to have the pool set spil the recipient, so the mined block already gives the prize to the pool no matter who broadcasts it, and 2nd (spil indicated by zanzu) the pool doesn’t actually bother providing the entire block out to miners, just a template for the header that contains the hashes of the actual block contents).

What the miner could do is secretly throw away the valid block instead of sending it back to the pool. That would hurt the surplus of the pool more than the miner because only a puny portion of the prize from it would have actually come back to them, and for a bunch of complicated spel theory reasons this could maybe result te an advantage if the same miner also had a lotsbestemming of other mining power not on the pool at all. (This is the “block withholding attack” I mentioned above). But it starts to be noticeable te the statistics if you do it a lotsbestemming, and also it doesn’t provide any benefit to the typical small-time miner. So thesis attacks are presumed to be fairly zonderling. There are certain types of prize schemes that are more or less resistant to the strategy, but most people don’t seem to be very worried about thesis attacks te general. So all ter all the basic “share” strategy is pretty much good enough.

TL,DR: shares are “failed blocks” that a pool uses spil evidence of a petite miner’s participation.

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