EPoW: Solving blockchain problems economically

Blockchain was first implemented in Bitcoin, the first decentralized digital currency, with the hash-chained blocks of data, hash-based proof-of-work, and a peer-To-peer protocol to reach consensus so as to append new blocks and secure transactions. Most importantly, it prevents double-spending after some confirmation time. However, few countries accept Bitcoin as a legal currency because, in addition to being subject to some security attacks, there are still problems in economics, politics, performance, etc. Many altcoins with different improvements have been proposed, but problems and attacks still remain. Meanwhile, blockchain, as a trust machine, has been applied to many other areas, such as smart contract, creating a new hype, called 'the most significant innovation since the Internet.' However, there are still similar problems and attacks in those applications. By changing the original consensus design, instead of just providing proof of work, we propose EPoW, i.e. estimable proof-of-work, to estimate how much work is done and a corresponding protocol to reach consensus. EPoW and the protocol can serve as a new instrument such that the problems and attacks mentioned above might be relaxed or solved economically. With EPoW, we believe blockchains and digital currencies can be better customized by companies, organizations or countries for different purposes or policies and be employed by any users. © 2017 IEEE.