  The protocol for cryptocurrencies can be divided into three parts, namely
consensus, wallet, and networking overlay. The aim of the consensus part is to
bring trustless rational peer-to-peer nodes to an agreement to the current
status of the blockchain. The status must be updated through valid
transactions. A proof-of-work (PoW) based consensus mechanism has been proven
to be secure and robust owing to its simple rule and has served as a firm
foundation for cryptocurrencies such as Bitcoin and Ethereum. Specialized
mining devices have emerged, as rational miners aim to maximize profit, and
caused two problems: i) the re-centralization of a mining market and ii) the
huge energy spending in mining. In this paper, we aim to propose a new PoW
called Error-Correction Codes PoW (ECCPoW) where the error-correction codes and
their decoder can be utilized for PoW. In ECCPoW, puzzles can be intentionally
generated to vary from block to block, leading to a time-variant puzzle
generation mechanism. This mechanism is useful in repressing the emergence of
the specialized mining devices. It can serve as a solution to the two problems
of recentralization and energy spending.
