How to Model the Bribery Attack: A Practical Quantification Method in Blockchain

Due to substantial profit gain and economic rewards, decentralized cryptocurrency systems have become primary targets for attackers. Double-spending is one of the most rudimentary and collective risks. Even without high hash power, attackers can still increase the probability of double-spending by bribing other miners to subvert the consensus agreement. This kind of attack is called bribery attack and a number of bribery attack models have been proposed during last few years. The evaluation and comparison of bribery attack models remain problematic due to the lack of systematic methods to quantify them. In particular, the costs and benefits of attackers are rarely considered which influenced by many factors. We propose a quantitative analysis method for previous bribery attack models. For further exploration, we design a bribery attack model and introduce profit formulations based on our analysis method. We experimentally prove that our model can reduce costs and increase benefits of bribery attacks compared with comparable models. The result shows our quantitative method is instructive both for bribery attack designing and analyzing.