Design And Implementation Of Blockchain Ciphertext Retrieval System Based On National Cipher Algorithm

The widespread application of cloud services has prompted a large number of users to outsource private data to cloud servers to relieve local storage pressure.In order to ensure the security of private data,the data needs to be encrypted before uploading to the cloud server,and the searchable encryption technology is used to realize safe and effective retrieval of ciphertext data.However,in the pay-as-you-go retrieval environment,some schemes have the problem of transaction inequity,that is,malicious cloud servers do not return correct retrieval results or malicious users interrupt retrieval halfway,and traditional ciphertext retrieval schemes only support single-user access.there are certain limitations.In view of the above problems,this thesis designs a blockchain ciphertext retrieval system based on national secrets based on the national secret algorithm,blockchain smart contract technology,attribute encryption and searchable encryption technology,which realizes the retrieval efficiency advantages of the system,a fair trading environment and many more.The user retrieves the scene.The specific research work is as follows:1.A fair and searchable encryption scheme based on the national secret algorithm is proposed.In order to ensure the security and controllability of the core algorithm of the scheme and the fairness of the transaction,the national secret algorithm and smart contract are introduced to optimize the traditional searchable encryption scheme.Firstly,using the SM3 algorithm to generate a 256-bit index and the simple structure of the SM4 algorithm,the key and data set are optimized.Then,combined with the characteristics of smart contracts to automatically fulfill the contract content,multiple contract functions are designed,and a fairness agreement is proposed to solve the unfairness of retrieval transactions between users and cloud servers in the cloud environment.The experimental results show that the generation and retrieval time of the secure index is in the millisecond level,and the overall time-consuming presents a linear growth curve,which is stable.2.A multi-user fair ciphertext retrieval scheme is proposed.Aiming at the problem that the traditional scheme only supports single-user retrieval,combined with the national secret algorithm and the attribute encryption mechanism based on the ciphertext strategy,CP-ABE is used to generate a tree-shaped access structure for the shared ciphertext data.As long as the attribute private key assigned by the registered user group can pass through the access structure,the user can obtain the decryption key,thus realizing the multi-user retrieval mode.The experimental results show that in the retrieval stage,the increase of data sets has little effect on the overall retrieval efficiency,and has certain practicability.3.Design and implement a blockchain ciphertext retrieval system based on state secrets.Based on the above-mentioned research algorithms and related technologies,the core algorithm of the system is nationalized,a fair transaction module,and a multi-user retrieval module is realized.According to the software design and development process,a blockchain ciphertext retrieval system based on national encryption is designed and implemented.Test analysis shows that the system has certain advantages in index generation efficiency and retrieval efficiency while ensuring security.