I was wondering how does a pool split this computationally difficult task into smaller tasks while at the same time preventing any individual miner to claim the reward if he happens to be the one hitting the correct solution?
The 'puzzle' that is solved contains, among other things, the Coinbase transaction that will assign the reward to the pool's address.
It the miner happens to solve the block himself, and instead of submitting it to the pool, he submits it somewhere else, it wouldn't matter since the pool is going to get the reward regardless.
And if the miner goes and modify the Coinbase transaction to assign the reward to himself, he will have to computed a new block hash... which, if you could do that, you should just always do that in the first place and skip the pool
.And if he ALWAYS changes the Coinbase transaction to assign the reward to himself "just incase", the pool will reject all his shares, and he wouldn't get any reward until he solves the block. Then might as well solo mine.
It's pretty ingenious if you think about it. Was it Slush who invented it? Either way, hats of to whoever did.