Revisiting the fairness and randomness of delegated proof of stake consensus algorithm

There are many disparate conceptualizations to secure a cryptocurrency network. Bitcoin relies on the proof-of-work mechanism and heterogeneous altcoins use proof-of-stake. Delegated Proof-of-Stake (DPoS), known to be a fast, efficient, decentralized, and highly flexible blockchain design, further offers some interesting reshaping that are well worth deliberating. In DPoS consensus, a panel of trusted parties (called committee of producers in the paper) has to be established, with all of its members eligible to create blocks and prevent non-trusted parties from participating. Deterministic selection of block producers allows transactions to be confirmed in an expected average of 1 second. The paper revisits the security properties of DPoS and reinforces the fairness and randomness for the algorithm without sacrificing its performance. We first scrutinize the limitations of the DPoS consensus, including predictability of producers, bribing producers, and lack of task incentivizing. We then introduce a cascade progressive-like ranking to judge the behaviour of the producers, and the producer who does not contribute to the network at the current interaction will be committed to a lower chance of being qualified for the coming involvement. More specifically, we conceptualize the tweaking parameters and the weights for the producers and bring in the weighted committee to measure the contributions of the producers. The weighted committee is a multiset derived from the committee and the weights specify the multiplicities of the elements (the producers). A pseudo-random process is also formulated to squeeze out the producer probabilistically from the weighted committee for creating the blocks. This unpredictability of the producers amplifies the randomness of the network and gives rise to a more secure and reliable cryptocurrency system. The proposal aspires to be beneficial for practical applications and the practitioners are as well encouraged to customize case-by-case the tweaking parameters and the pseudo-random process.