Alt-PoW: An Alternative Proof-of-Work Mechanism

Bitcoin is the world's most successful digital currency. It uses a public distributed ledger called the blockchain to maintain the transaction history in the network. It employs a Proof-of-Work (PoW) protocol for miners to add more blocks of transactions to the chain in order to arrive at a consensus of the state of the network. Due to the nature of the consensus mechanism used, miners are not given any sense of their progression when solving a PoW problem. The only strategy presented to them is a brute-force search where it is unknown to them how far away they or other miners are to a solution, and if the problem is worth dedicating further resources to. This results in a slow and highly energy inefficient consensus protocol. In this paper we present an alternative PoW mechanism which introduces the idea of progression when solving such puzzles. This Alt-PoW mechanism gives participants a network view of how all other miners are faring in the block finding process, so they can decide whether it is in their interest to withdraw from a block race or to continue dedicating their resources towards it. We also present a mechanism to allow for multiple interconnected chains as opposed to a single blockchain, so that block finding can be parallelized. Participants can decide which chain to dedicated their resources to, based on which has the best chance of them being successful mining on at any particular time. We show that this results in a faster and more energy efficient protocol.