p2pool

Overview

P2Pool shares form a "sharechain" with each share referencing the previous share's hash. Each share contains a standard Fastcoin block header, some P2Pool-specific data that is used to compute the generation transaction (total subsidy, payout script of this share, a nonce, the previous share's hash, and the current target for shares), and a Merkle branch linking that generation transaction to the block header's Merkle hash.

The chain continuously regulates its target to keep generation around one share every six seconds, just as Fastcoin regulates it to generate one block every twelve seconds. This means that finding shares becomes more difficult (resulting in higher variance) the more people mine on P2Pool, though large miners have the option to raise their difficulty, and so reduce the impact of their mining on P2Pool's minimum difficulty.

Unlike Fastcoin, nodes do not know the entire chain - instead they only hold the last 8640 shares (the last day's worth). In order to prevent an attacker from working on a chain in secret and then releasing it, overriding the existing chain, chains are judged by how much work they have since a point in the past. To ascertain that the work has been done since that point, nodes look at the Fastcoin blocks that the shares reference, establishing a provable timestamp. (If a share points to a block, it was definitely made after that block was made.)

Fastcoin P2Pool Nodes

• http://fst.inetrader.com:5150/
• http://p2pool-mining.org:5150/
• http://midserv.dyndns.org:5150/