alt Hacker News> If a pool can set up a situation where they mine a block and wait X seconds to reveal it, they can force other miners to waste X seconds of has power and gain an advantage.
How is it wasted if they work on the current chain? If they find a block during those X seconds, they'll propagate it before the waiting pool does. The waiting pool will then just lose the revenue from the block they put on hold. They're the ones wasting mining time when that happens, while the others never do.
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Right, but the odds of this happening is small(ish) - I'm certain there is a sweet spot for witholding time. If they don't find a block within the time interval, then effectively all the work for that time is "wasted" by the other participants since it could not have been put on the chain anyway AND the witholder has a headstart of a couple of seconds searching for a new block.
I might be wrong but I think it's like this..
A finds a block after 1 minute, then powers off and waits for another minute. They reveal the block after 2 minutes.
B searches for the block for 2 minutes.
After 2 minutes, A has used 1 minute of their compute, and B has used 2.
If you mine a block without revealing it, not only are you the only one that can mine the next block after that, but everyone is mining on the "wrong head". There's of course the risk that someone finds a different head in the meantime, but otherwise, you waste competitors' resources, while you get an advantage on the next block.