user2582: I have not been able to find any method that pools use to verify you've done the work you say you did. So if someone does a solution withholding attack but without actually knowing what the solution is in a PPS pool then can't this attack just get free coins?

user575: Miners submit shares to the pool to prove that work has been done. Shares are easier hashes than blocks (by default, one in 2^32 hashes will be a share), and there is no way to find shares without doing the work needed to find blocks. See also What is a share? Can I find it while mining solo, or only when pool mining?
However, a miner can do the work but still refuse to send valid blocks if he finds them. This is called block withholding and can be used in several attacks.

user4867: Well, first of all when you submit a share, it gets validated through the BTC/LTC client/daemon. If it is the correct solution to a block, then poof, an incoming transaction of 25BTC / 50LTC appears in the pools transaction history. This is called an "immature" transaction.
Most of the pools run PPS / PPLNS as a reward system. Meaning the more shares you submit, the more payout you get in proportion to the total number of shares during a round. Most pool software use some kind of database to insert the valid shares into to keep track of the work done for each worker/miner.
As far as I know, you get no "special" reward for finding a block... If you do, that's some pool-sided setting. Some pools use PC games as rewards for finding blocks, etc etc. But you don't get some kind of increased LTC/BTC.
If you mean that you withhold the valid share, and then submit it locally so only you get the full rewards? That won't work either, since you need your local bitcoin/litecoin daemon to run, and fetch work from. If you submit a share you haven't got work for, to another litecoin/bitcoin daemon, it won't get accepted, since the server knows that they haven't issued this work to you.
Hope this answers some questions.

2582: <p>I have not been able to find any method that pools use to verify you've done the work you say you did. So if someone does a solution withholding attack but without actually knowing what the solution is in a PPS pool then can't this attack just get free coins?</p>
 575: <p>Miners submit shares to the pool to prove that work has been done. Shares are easier hashes than blocks (by default, one in 2^32 hashes will be a share), and there is no way to find shares without doing the work needed to find blocks. See also <a href="https://bitcoin.stackexchange.com/questions/1505/what-is-a-share-can-i-find-it-while-mining-solo-or-only-when-pool-mining">What is a share? Can I find it while mining solo, or only when pool mining?</a></p>

<p>However, a miner can do the work but still refuse to send valid blocks if he finds them. This is called block withholding and can be used in several attacks.</p>
 4867: <p>Well, first of all when you submit a share, it gets validated through the BTC/LTC client/daemon. If it is the correct solution to a block, then poof, an incoming transaction of 25BTC / 50LTC appears in the pools transaction history. This is called an "immature" transaction.</p>

<p>Most of the pools run PPS / PPLNS as a reward system. Meaning the more shares you submit, the more payout you get in proportion to the total number of shares during a round. Most pool software use some kind of database to insert the valid shares into to keep track of the work done for each worker/miner.</p>

<p>As far as I know, you get no "special" reward for finding a block... If you do, that's some pool-sided setting. Some pools use PC games as rewards for finding blocks, etc etc. But you don't get some kind of increased LTC/BTC.</p>

<p>If you mean that you withhold the valid share, and then submit it locally so only you get the full rewards? That won't work either, since you need your local bitcoin/litecoin daemon to run, and fetch work from. If you submit a share you haven't got work for, to another litecoin/bitcoin daemon, it won't get accepted, since the server knows that they haven't issued this work to you.</p>

<p>Hope this answers some questions.</p>
