Research On Combined Attack Strategy For Public Chain

The public chain represented by Bitcoin is one of the most important blockchain networks in the world today,and its underlying support technology and application methods have had a profound impact on the existing blockchain technology.But the public chain itself also faces a series of security threats.One of the most serious security threats is the mining at-tacks against Bitcoin mining protocols represented by selfish mining attacks.In order to resist mining attacks,researchers must establish corresponding attack models to establish the basis for subsequent defense strategies.At present,there are many attack strategies and models for Bitcoin mining protocols,but most of these studies are aimed at a single mining attack strategy.Only FAW attack strategies can be classified as combined attack strategies.The FAW attack strategy has the problems of over-complex state transition,poor flexibility and poor scalability.In response to the above problems,this thesis proposes a new combined attack strategy called Selfish-With-Discard(SFD).The SFD attack strategy enables attackers to obtain higher revenues than the selfish mining attack strategy,block discard attack strat-egy and FAW attack strategy within a certain computing power,thus expanding the research on mining attack models.The specific work of this thesis is as follows:This thesis builds a simple SFD model that includes a selfish mining pool and an honest mining pool,and describes the macro structure,state space,and attacker action strategy of the simple SFD model.On this basis,this thesis proves that the simple SFD model has a stable distribution,and derives the expression of the attacker distribution probability and the attacker's expected revenue under the simple SFD model.This thesis also compares the sim-ple SFD attack strategy with the classic selfish mining attack strategy,block discard attack strategy and FAW attack strategy.The comparison experiment shows that when the comput-ing power held by the attacker is less than 20% of the total computing power of the blockchain network,the simple SFD attack strategy can allow the attacker to obtain higher revenue than the classic mining attack strategy and block discard attack strategy.This thesis also explores the impact of other factors on the attacker's revenues through comparative experiments.In the process of comparison with the FAW attack strategy,it is found that when the attacker's total computing power increases,the growth rate of the attacker's revenue under the simple SFD model is faster than that of the FAW attack model.When the attacker's total computing power is fixed,under the simple SFD model,the attacker can adjust the other parameters to obtain better revenues than the FAW attack.This thesis builds the multi-honest mining pool SFD model and describes the macro structure,state space and attacker action strategy of the multi-honest mining pool SFD model.This thesis also discusses the changes in the multi-honest mining pool SFD model when the block discard attacker turns to honest mining.On this basis,this thesis derives the general attacker distribution probability expression of the multi-honest mining pool SFD model,and takes two honest mining pool SFD models and three honest mining pool SFD models as examples to derive the attacker's expected revenue expression.The comparison experiments of the two and three honest mining pool SFD models with the classic selfish mining attack strategy,block discard attack strategy,simple SFD attack strategy and dual mining pool FAW attack strategy show that in different parameter spaces,the attacker It is always possible to adjust the controllable parameters to obtain higher revenues than the FAW attack strategy and the classic selfish mining attack strategy.At the same time,the comparison experiment with the simple SFD model shows that under the same parameter conditions,the increase in the number of honest mining pools is more beneficial to attackers.