Isn't there a simple way to find out? How about a couple of supecting miners decide to use a slightly modded miner that would inform the user when it finds a block.
It'd be sufficient for this group to be able to present only 1 block that was stolen by the operator.
Of course they would have keep their identities secret, otherwise the pool operator can just always leave their blocks untouched and choose blocks of other miners for stealing.
This would at least create a lot of danger for the pool operator. The pool operator getting caught stealing would certainly destroy the pool, so even a slight danger of that happening should keep him from stealing, right?
Am I overlooking something?
That makes perfect sense. What I don't understand is why a mining client can't just keep the block and all 50 BTC for itself when it finds the block. Is there some protection against this happening that would also prevent a mining client from knowing when it finds a block?
From the period starting at block 137872 to 139410, initially it looked like something was fishy because BTCG found less blocks than Slush despite having higher hashrate, but over the period, this slowly corrected and BTCG found more blocks than Slush, with Slush performing below par (all the top pools were getting about 5.5~6.5 BTC per GH/s while Slush was just below 5). So I figured there probably was nothing fishy going on but merely that the run of bad luck got everybody paranoid and left it at that.
That would suggest that BTCGuild is working with at least one other mining pool to pull this off.
Here is what I think may be happening after thinking about it for a little while. BTCGuild and some other pools, such as Deepbit, or Slush or Ars Bitcoin are actually run by the same people.
The operator of BTCGuild is intentionally manipulating the luck in the pool making it drop very low and then jump up to unexpected highs. On low luck days, they would be doing this by having the pool capture some of the winning shares and sending them over to one of the other pools where that share would be sent out to one of the miners to win. On high luck days, some of the winning shares on the other pools would be captured and sent over to BTCGuild and sent out to the miners to have them win.
During this time, some of the winning shares may be sent off to a private pool where some of the loot is kept, or are sent off to a PPS pool like Ars Bitcoin and help build up that big 800 BTC buffer that they have. Then somebody gets to keep that buffer.
But the amount of actual stealing that takes place depends on weather or not people notice. By manipulating the pool and adding positive luck, it really a great way to make most people not notice that something is wrong. So right now there is probably very little stealing actually going on but there is still a high degree of manipulation!