Research On Key Technologies Of Rational Attack And Defense For Blockchain Transaction

Blockchain technology is one of the important infrastructures in the process of upgrading and transforming the digital economy,however,there are a series of security issues in the process of integration and application.In particular,attacks against the blockchain system consensus mechanism,smart contracts and other system vulnerabilities have posed different degrees of hidden dangers to the security of the blockchain system.Meanwhile,with the emergence of numerous blockchain system applications,cross-chain interoperability between multiple blockchain systems are becoming increasingly frequent.Cross-chain atomic exchange is one of the most common ways of cross-chain interoperability,but the security and fairness of both sides of the transaction also face many threats and challenges.This thesis aims to employ game theory and machine learning to research the key technologies of transaction security and fairness in blockchain systems as the subject of research.With the extension of security margins from a single blockchain system to the whole blockchain ecosystem,a cross-chain exchange protocol that takes into account atomicity,security,and fairness is constructed.The main research contents and contributions of this thesis are as follows.(1)To address the security problems caused by the vulnerabilities of consensus mechanisms and smart contracts in blockchain systems,this thesis introduces the concept of rationality to study the attacks initiated by mining pools and the attack behaviors among mining pools and analyzes and studies various types of attacks from the perspective of incentive mechanisms.By sorting out the initiation mechanism of classical attacks,a rational strategy-based optimal attack and defense equilibrium model is constructed by combining game theory.The uniqueness of the best pure strategy can be used to guide the study of attack strategy optimization,defense strategy optimization,and the equilibrium state of attack and defense confrontation respectively.This is also the theoretical basis and rationale for the attack and defense adversarial research on blockchain systems in the subsequent chapters of this thesis.(2)This thesis introduces the idea of offense and defense and the theory related to the Hidden Markov Decision Process,constructs an attacker view,studies the optimization of selfish mining attack strategy from the attacker’s perspective,and proposes the concepts of semi-selfish computing power and semi-selfish participants,so as to constructs a new type of attack,named semi-selfish rational attack.The results of the simulation experiments show that the semi-selfish rational attack has a lower computing power threshold,better concealment,and greater destructive power than the selfish mining attack,which deserves the high attention of researchers in the field of blockchain system security.(3)This thesis constructs a defender’s view,then gives an observable state sequence based on the defender’s view and the various states defined,derives the hidden state sequence and the payoff matrix backward,and considers the effect of the overall size of the attacker’s-controlled computing power on the payoff.Under fixed conditions,the simulation experiments show that although it is profitable to launch semi-selfish rational attacks,the probability of successfully launching an attack without being detected is as low as 2.727586053900219e-232.This theoretically supports the fact that selfish mining attacks and their variants are extremely uncommon in real blockchain systems.(4)With the deployment of a large number of heterogeneous blockchain systems,the blockchain ecology becomes increasingly complex.To address the phenomenon of blockchain system heterogeneity,this thesis constructs a new cross-chain transaction protocol HT~2RE~2P by using timed-release encryption,elliptic curve Diffie-Hellman key exchange mechanism,combined with traditional hash time lock protocol and national secret SM3 hash function,focusing on improving the fairness of both parties involved in the cross-chain transaction protocol under the premise of guaranteeing transaction atomicity.This thesis constructs the HT~2RE~2P model under the UC framework,conducts security reduction and security proofs for the constructed ideal functionality,and performs proof analysis on the protocol’s atomicity and fairness.