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2010-11-27: Slush Pool Announced

Slush [Marek Palatinus], Bitcoin Talk post #1976:

Cooperative Mining
November 27, 2010, 01:45:41 PM:

Once people started to use GPU enabled computers for mining, mining became very hard for other people. I'm on bitcoin for few weeks and didn't find block yet (I'm mining on three CPUs). When many people have slow CPUs and they mining separately, each of them compete among themselves AND against rich GPU bastards ;-), because everybody counts sha256 hashes from the same range. Two separate CPUs with 1000khash/s isn't the same as one 2000khash/s machine!. But new feature of the official bitcoin client called 'getwork' now enables work of many computers together, so they don't compete. Because there is now standalone CPU miner (thanks to jgarzik!) and 'getwork' patch is in official client now, I have an idea:

Join poor CPU miners to one cluster and increase their chance to find a block!

How that should work? There will be web page where you can register, enter your wallet address and get URL and your personal rpcuser/rpcpassword for your CPU/GPU miners. When you start own miner with these credentials, server will send you work which was not calculated yet by other members of cluster.

But when your client find winning hash, you do not get full reward for block (50BTC right now), but only proportional part, which you calculate. When you offer 1000khash/s for one day and whole cluster performance will be 20000khash/s and it takes two days to find a block, your reward will be (50/20/2=)1.25BTC.

Advantages? When you have poor standalone computer, you need to wait many weeks or even months for finding full 50BTC reward. When you join cluster like this, you will constantly receive small amount of bitcoins every day or week (depends on full cluster performance).

Disadvantages? You need to trust in central authority (me) that I don't steal block for myself. But I'm goofing around for few week and I'm amazed with bitcoin idea, so I don't plan to steal anybody right now :-).

[The following was redacted by the author. -Ed.]
Another possible problem is that somebody will ask for new work very often, but in fact he will not count real hashes. In this case it will look like he has very strong CPU and he should get big part of reward if cluster find a block. But there is a simple defense against cheaters: Central server sometimes send work which leads to 'winning' hash. Worker which don't return this hash as matching will be permanently banned (login/password and IP address). This was succesfully solved by letting miners calculate proof-of-work. It is not anymore possible to be a part of cluster and not count hashes. [End redaction]

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