Proof of Activity Consensus Algorithm Based on Credit Reward Mechanism

Proof of Activity (PoA) is a key algorithm to reach consensus among nodes. In current PoA, N online representative nodes are only used to create one transaction block, and the probability of creating a block by malicious nodes cannot be controlled, which leads to a serious waste of computing power. An improved algorithm proposed in this paper introduces credit reward mechanism to replenish the missing trust in current PoA. It also can control the probability that the node obtains the right of creating block head and trading block according to the credit value and set up the reward and punishment scheme according to the proportion of credit value, which decrease the cost of good node generating block with increasing credit value and increase the cost of malicious node creating block significantly. The algorithm uses Byzantine fault tolerant idea and follow-the-Satoshi mechanism to select representative nodes through multi-level selection and set different workload for the nodes at different levels, by which the probability of malicious nodes creating transaction blocks is reduced effectively. The experimental results show that the number of transaction blocks in a block header in CPoA is 1.75 times increase than PoA. The reward and punishment scheme can achieve the purpose of dealing with malicious nodes quickly. When the proportion of malicious nodes increased from 30% to 70%, the average decline rate of their overall credit value increased about 1.7 times, which reduces the probability of malicious nodes creating blocks, increases the cost of malicious nodes creating blocks, and enhances the stability of the system.