A novel blockchain-based and proxy-oriented public audit scheme for low performance terminal devices

With the rapid development of cloud computing technology, more and more individuals/organizations are inclined to store their data in cloud server (CS). Cloud storage audit schemes can help data owner (DO) to confirm the integrity of their data, but the existing schemes still have some limitations. On one hand, the existing schemes assume that DO's terminal devices are computationally powerful enough to handle various operations in a timely manner. While in practice, the terminal devices probably are mobile phones, tablets and other devices with low computing power. On the other hand, the existing schemes rely on a fully trusted third-party auditor (TPA), but it is not in line with real application scenarios. Therefore, in this paper, we proposed a novel blockchain-based and proxy-oriented public audit (BBPO-PA) scheme for low performance terminal devices. Firstly, we introduced a trusted proxy authorized by DO, which can process and upload DO's encrypted files. Secondly, we applied blockchain in our scheme and utilized smart contracts instead of untrusted TPA to improve the reliability and stability of audit results. Thirdly, we took advantage of an index table to ensure that our scheme can support dynamic data operation. Finally, security analysis revealed that our scheme is provably secure in random oracle model. Meanwhile, performance analysis demonstrated that our scheme is efficient and especially suitable for low performance terminal devices.