Scheme (mathematics)

Computer security

Encryption

Accounting

Operating system

SSH File Transfer Protocol

Economics

Ring signature

Blockchain

Computer science

Cloud computing

Business

Public-key cryptography

Cloud storage

Alternative medicine

Database

Mathematics

Management

Audit

Group signature

Data file

Mathematical analysis

Upload

Medicine

Stub file

Data sharing

Pathology

Concurrency and Computation Practice and Experience

Summary In a data sharing group, each user can upload, modify, and access group files and a user is required to generate a new signature for the modified file after modification. There is a situation that two or more users modify the same file at almost the same time, which should be avoided as it gives rise to a signature conflict. However, the existing schemes do not take it into consideration. In this paper, we proposed a new mechanism SeShare for data storing based on blockchain to realize signature uniqueness, which solves the problem of generating signatures for the same file meanwhile by different group users. Specifically, we record every signature of a file in a blockchain in chronological order, and only one user is allowed to add new signature at the end of the blockchain when modification conflicts occur. On the other hand, to provide a secure data sharing service, SeShare introduces an efficient public auditing scheme for file integrity verification when a group user leaves the group. We also prove the security of the proposed scheme and evaluate the performance at the end of this paper. Our experimental results demonstrate the efficiency of public auditing for user leaving.

SeShare: Secure cloud data sharing based on blockchain and public auditing