Design And Implementation Of E-Voting System Based On Full Homomorphic Encryption

The application of electronic voting becoming more and more widely used with the support of information security and computer network technology.However,most of the current e-voting system comes with the ballot secret,anonymity and other aspects shortcomings,which caused the correctness and fairness,is questioned.This thesis designs and implements an electronic voting system with higher security guarantee for the security problem during ballots counting,which meets at medium and large voting scenes by adopting the technology of full homomorphic encryption(FHE),digital signature and network programming.And with ensure the safety of the system,the performance of the system is improved as much as possible.According to the voting scheme based on FHE and combined with traditional voting model and the design requirements,this thesis proposes the overall program design scheme of the e-voting system.According to the overall design,the thesis completes the authority certification center(AC)which provides key generation and management and co-ordination of the voting process and other functions,the counting center(CC)which offers ballots verification and calculation directly in ciphertext,the bulletin board(BB)which for voting results verification,and the voting client(VC)working under Windows and Android respectively.The main contribution of this paper includes:(1)For the confidentiality and security issues brought by general e-voting system which need to decrypt the secret ballots during counting process,this thesis uses FHE on ballot encryption and ciphertext counting device(CCD)on ballot counting in ciphertext directly.CCD is designed based on HElib which realized in BGV scheme.The counting of the ciphertext ballots directly makes the counting process safe and credible,which also reduces the dependence of the counting center on the third party trusted outsourcing computing platform simultaneously.(2)For improving the lower performance when using ripple carry adder(RCA)to construct CCD,the carry look ahead method is used to optimize the RCA circuit,and the Kogge-Stone homomorphic cryptography adder implemented(KSA)which reduces n-bit RCA cipher operation circuit depth from O(n)to 2O(log n),finally combine with SIMD technology the counting performance is boosted.(3)For counterfeiting ballot papers in voting,this thesis uses high anti-collision registration certificate,combined with RSA digital signature and MD5 message digest algorithm to verify the votes to prevent illegal voting,which also leads the system supports verifiability.(4)For the congestion problem caused by instantaneous centralized voting,the multi-thread network programming technology based on TCP/IP is used to decouple access request and service processing by using asynchronous programming method,which makes the system have high concurrent voting service capability.The system is simple and easy to deploy which achieves the more secure feature during counting stage goal with a certain practical value.Tests show that KSA,which corresponds to 16-bit plaintext additions,is reduced by 56 percent over RCA's time-consuming expenses.And the use of KSA's votes at a size of 65535 voters was reduced by 72% over the previous RCA.