Affiliations: State Key Laboratory of Integrated Service Networks, Xidian University, Xi’an 710071, China. [email protected], [email protected]
Correspondence:
[†]
Address for correspondence: No.2, South Taibai Road, Hitech Development Zone, Xi’an City, Shaanxi Province, China.
Note: [*] Also works: Guangxi Key Laboratory of Cryptography and Information Security, Guilin University of Electronic Technology, P. R. China, Xianyang Vocational Technique College, P. R. China.
Note: [‡] This work was supported by the National Key R&D Program of China under Grants No. 2017YFB0802000, the National Natural Science Foundation of China (No. 61572390, 61473029, 61672412, 61772550), the Natural Science Foundation of Ningbo City under Grants No. 201601HJ-B01382, and the Open Foundation of Key Laboratory of Cognitive Radio and Information Processing, Ministry of Education (Guilin University of Electronic Technology) under Grants No. CRKL160202. The first author was also supported by National Cryptography Development Fund of China (Grant No. MMJJ20170112), Guangxi Key Laboratory of Cryptography and Information Security (No GCIS201610).
Abstract: Recently how to audit cloud storage correctly and securely is a very hot research topic for cloud storage. At Infocom 2015, Chen et al. proposed a novel secure cloud storage audit protocol based on distributed string equality checking, which is a very interesting result. In this paper, we give some improvements to their protocol to strengthen its security. In particular, we show that if the data owners reuse pseudorandom function on the same order number of file block when uploading file block’s tag to the cloud, the protocol maybe not secure any more. We also show that there can exist many (mi, ci) pairs which will result in the same inner product sum ∑i=1nmi⋅ci, while mi denotes the file block, ci denotes the challenge value, and n denotes the number of blocks. We emphasis here that the flaw maybe does not lie in the traditional security model of cloud storage auditing protocol, but we think it is actually a serious drawback for current secure cloud storage audit protocols. We emphasis these two flaws can also exist in some famous cloud auditing protocols such as PDP and POR. Finally, we give an improvement to their protocol, and thus also give a way to strengthen the famous PDP and POR protocols.
