Research On Blockchain Privacy Protection Mechanism Based On Ring Signature

Blockchain technology is an emerging technology and frontier hotspot in recent years,among which the blockchain privacy protection mechanism is a research hotspot.The traditional blockchain only realizes the simplest pseudonymity and cannot meet the increasing privacy needs of blockchain users.In order to solve this problem,a variety of blockchain privacy protection mechanisms have been proposed,such as mixed currency mechanism,ring signature mechanism,and zero-knowledge proof mechanism.Blockchain privacy protection mechanism based on ring signature is one of the most important mechanisms.It uses mixed addresses to form a ring with real input,and then generates a ring signature to hide the real input.One of the most successful implementations of blockchain privacy protection mechanisms based on ring signatures is Monero.Monero has two major characteristics: unlinkability and untraceability,both of which guarantee the privacy of Monero transactions.Monero's privacy protection mechanism is not perfect,it still faces some privacy attacks and threats.Therefore,this paper does the following work for the ring signature-based privacy protection technology used by Monero.1.It summarizes and analyzes various types of attacks in the blockchain privacy protection mechanism based on ring signatures.Among them,the most influential and the most harmful to the privacy of the blockchain are zero-mix transactions and chain reaction attacks,time analysis attacks,ringbased attacks,key reuse attacks,and flood attacks.The paper carefully analyzes the attack process and effect of various attacks,and also summarizes and analyzes the current effective countermeasures against various types of attacks.Not only analyzes the advantages of various countermeasures,but also points out the shortcomings of existing countermeasures,and lays the foundation for proposing better solutions.2.A ring signature privacy protection scheme based on fixed ring set is proposed.The core of this solution is to guide users to choose mixed addresses.The ring signature mechanism of the fixed ring set breaks the user's original random and uncontrolled mechanism for selecting mixed addresses.Instead,the fixed ring set assigned by the system is used to replace the randomly selected mixed address.The superiority and innovation of this solution lies in that it can completely resist multiple attacks such as time attack and solve the problem from the fundamental source of choosing a mixed address.Not only that,but also a quantitative analysis of the privacy security of this scheme.3.A transaction verification mechanism based on UTXORS(Unspent Transaction Output Ring Set)is proposed.The concept of UTXO is proposed,and the data structure of UTXO is defined.Miners maintain a UTXORS pool locally to replace all key images in the blockchain,and determines whether the transaction input is valid by verifying whether the transaction input appears in the UTXORS pool.This transaction verification mechanism solves the problems of excessive memory consumption and long search time caused by the original miners storing all key images,making the transaction verification process efficient.