Peercoin

A peer-to-peer crypto-currency design derived from Satoshi Nakamoto's Bitcoin. Proof-of-Stake replaces Proof-of-Work to provide most of the network security. Under this hybrid design proof-of-work mainly provides initial minting and is largely non-essential in the long run. Security level of the network is not highly enery dependent thus providing an energy efficient and more cost-competitive peer-to-peer crypto-currency. Proof-of-Stake is based on coin age and generated by each node via a hashing scheme bearing similarity to Bitcoins but over limited search space. Block chain history and transaction settlement are further protected by a centrally broadcasted checkpoint mechanism.