Research On Secure Outsourced Data Sharing Scheme

With the advantages of ultra-large scale,high scalability,and ultra-low cost,cloud computing attracts more and more users to use the cloud services.Data sharing is the basic service provided by cloud service providers for users,and it is also the most common practical application demand among them.In the outsourcing data environment,the cloud server is not limited to be used as a container for storing data.To reduce the storage and computing burden of data owners when sharing data,the solution can be to transfer the complex work that originally needs to be undertaken by data owners to the cloud service providers with better performance and richer resources.The data owner stores the data in the cloud server,which makes the physical storage of the data inconsistent with the actual ownership of the data.Therefore,we believe that data outsourcing is the root cause of the separation of data ownership and data control,and also causes many security problems of outsourced data sharing.This paper aims to solve the related problems of outsourcing data sharing,and analyze the complex cloud environment with many threats and the data sharing methods adopted by the mainstream of cloud service providers.In order to meet the requirements of high efficiency,security and fine-grained sharing of outsourced data,a certificate free conditional proxy re-encryption algorithm without bilinear pairing is proposed.Based on this algorithm,a scheme for fine-grained sharing in outsourcing data scenario is designed.The main work and innovation of this paper are as follows:(1)This paper analyzes the cloud data sharing methods of several enterprises,and further determines the fine-grained security sharing requirements of outsourced data based on the current situation of outsourced data security sharing in the cloud environment.Fine granularity refers to that the data owner can share the outsourced data to the authorized user under the specified authority according to the different authority,so that the authorized user can obtain the data content under the corresponding authority.The security is reflected in that the shared data is encrypted in the cloud storage and various transmission processes,and the unauthorized users and cloud service providers cannot access and use the data.(2)Based on the deep research on proxy re-encryption and the comparison of the characteristics of different proxy re-encryption,this paper proposes a undirectional and single used proxy re-encryption system.The algorithm not only retains the advantages of certificate free management and free key escrow,but also meets the fine-grained requirements of outsourced data sharing.In this paper,the proxy re encryption without certificate satisfies the adaptive chosen ciphertext security under the random oracle model,and the bilinear pair is not used in the specific construction of the algorithm.(3)A scheme of fine-grained sharing of outsourced data based on the certificateless conditional proxy re-encryption algorithm is also proposed.In this scheme,the shared data is encrypted by symmetric encryption algorithm,and the certificateless proxy re-encryption algorithm is applied to symmetric key.Taking the shared structured report card of the campus educational administration information management system as an example,the basis for dividing the conditions and the details of the implementation of the scheme are clarified.By analyzing the performance of the scheme,it is shown that the scheme can well realize the fine-grained sharing of outsourced data.