Blockchain- Based Secure E-Voting System

With the progress of society,many application scenarios require voting.In the Internet era,e-voting has replaced traditional paper voting forms with advantages of low cost,high work efficiency,and low errors.Since the data of electronic voting systems is stored in the central database,the following problems exist: the voting data is not open and transparent,easily being falsified and forged;the user's private information is at risk of being leaked;voters cannot verify the voting results.Blockchain technology originates from Bitcoin that is a consensus-based and non-centralized database with decentralized,traceable,non-modifiable and quasi-anonymous features.However,Blockchain technology can make up for the deficiencies in the current voting system,make the voting process open and transparent,prevent fraudulent balloting,enhance the security of voting data,and achieve verifiable voting results.Therefore,it is of great significance and prospect to study the application combined with Blockchain.The main tasks of this thesis include the following aspects:1.This thesis describes in detail the development process of safe and efficient e-voting system at home and abroad,deeply researches the related technologies and theories of Ethereum Blockchain,and introduces the development status of electronic voting systems combined with Blockchain in detail.2.This thesis proposes an e-voting scheme based on a distributed EIGamal encryption scheme and a zero-knowledge proof protocol.The scheme can achieve the voting methods of multiple candidates,with self-counting function,no need for third-party counting agencies,and has good practicality.The scheme uses EIGamal encryption system to ensure the secure transmission of the ballot data.At the same time,according to the EIGamal encryption system's multiplicative homomorphism,statistics of encrypted ballots can be achieved,which protects the privacy of the ballot.In addition,the scheme uses a zero-knowledge proof protocol to ensure the legitimacy of voter and ballot data,prevent duplicate votes.The security analysis shows that this scheme satisfies the security requirements of electronic voting protocols and maximizes the privacy protection of voters.3.This thesis designs and implements a smart contract based on the proposed secure voting scheme.The smart contract of voting scheme is divided into three parts: the main contract,the function of calling the other two smart contracts through the address of the contract and the application binary interface(ABI)file;the voting agreement contract,the key step in controlling the voting process;the encryption contract,responsible for creating discrete logarithmic knowledge The verification parameters of the certification agreement and the legality knowledge certification agreement and the method of ballot encryption.4.This thesis develops and implements a voting system based on the Ethereum blockchain.Using Node.js technology and Electron technology to implement the voting system's two clients which include voters,a voting sponsor,and a set of interfaces for calling the voting protocol's smart contract related methods.Our voting system is developed through the Ethereum Web3.js library which will make our voting system to fully execute the business logic of the voting protocol.The performance of our voting system is tested on the Ethereum's private chain,and the test contents include the cost and gas consumption of key methods.The test results show that the blockchain-based voting system designed in this thesis has good performance,and it also proves the feasibility and correctness of the voting scheme in this thesis.