Improvement Of Homomorphism Encryption Scheme For Cloud Computing

At present,cloud computing has become the industry that the major Internet companies focus on,intensify efforts to promote the commercialization of cloud computing.But the services provided by the major cloud service providers frequently have the security problems which have affected the trust of users for the cloud computing,especially in the public cloud,greatly restricted the promotion of cloud services represented by public cloud.In the cloud computing security issues,the most users concerned about the problem is the data security issues.In order to protect the cloud data,lead the homomorphic encryption scheme into cloud to improve security.The homomorphism in homomorphic encryption schemes means that the ciphertext can be calculated directly after the upload of the ciphertext,the effect is equivalent to the calculation of the plaintext.This would solve the data leakage problem in the public cloud environment.The current scheme of optimization and improvement of the homomorphic encryption algorithm is not suitable for real life because of some problems that the performance of program isiveness very low and the stored public key size is too large.In this dissertation,the offset public key compression scheme and the improved modulus technique are adopted to optimize the DGHV scheme and solve the above problems.At the same time,the performance and security of the improved scheme are analyzed in theory.Finally,the results of theoretical analysis are verified by experiments.The main research direction of this dissertation is to the application of homomorphic encryption in OpenStack.The following works have mainly be done.(1)First,To make a detailed introduction to Homomorphic encryption scheme that based on integer,And then generalize the Hierarchical homomorphic encryption scheme,and compare the two scheme.Then,according to the characteristics of cloud computing service,The PKI technology for identity authentication in cloud computing and the homomorphic encryption algorithm,PKI is used to complete the authentication and key distribution at the time of initialization,the method of homomorphic encryption is used to complete key generation and data encryption storage,are used to solve the security problem in multi-user environment in cloud computing.(2)In addition,a new scheme based on offset public key compression and improved modulus technology is proposed.Taking the DGHV scheme as the main construction idea,the data of the first encryption is increased from the original 1 bits to the k bits by changing the modulus mode,and the size of the public key is reduced by adopting the offset public key compression method.A scheme is proposed to optimize the encryption and public key dimensions,and be analyzed in theory.(3)This dissertation applies the new scheme under OpenStack to verify the availability of the scheme with experimental data processing.The experiment based on the improved homomorphic encryption scheme shows that the correctness of the improved homomorphic encryption scheme in the cloud computing environment...