Abstract: In cloud storage service,the user data are stored in untrusted cloud storage server and faced with security threat.In order to check whether all the file replicas are stored by the CSP intactly,a multiple-replica provable data possession scheme based on Paillier encryption and supporting the dynamic operation of data replica was proposed,namely the DMR-PDP scheme.To realize multiple-replica check,the file blocks are stored in the cloud server in the form of co-pies,and differentiable replicas are generated by using Paillier encryption system to encrypt the concatenation of the serial numbers of replicas and the file.The verifying tags are generated by BLS signature,which can batch checking of all replicas.The information of file identification and block position are added into the block tags to prevent both of the replacing and replay attacks from the CSP.The security analysis and simulation results show that the scheme is better than other literature methods in terms of security,communications and computational overhead,greatly improves the efficiency of file storage and validation,and reduces the computational overhead.

Key words: Cloud computing,Cloud server provider(CSP),Multiple-replica,Dynamic multiple-replica provable data possession(DMR-PDP),Paillier encryption system