A new publicly verifiable data possession on remote storage

In this paper, a new verifiable data possession construction supporting both private and public verifiability simultaneously is proposed from a linearly homomorphic cryptography method, which allows a server to integrate l selected block-tag pairs into a single block-tag pair as a response to user's query. In our scheme, the data owner who uses the private verification and anyone else who runs the public verification algorithm simultaneously on the same set of meta-data and based on the same setup procedure can securely authenticate the integrity of client's data file stored at cloud server without retrieving the whole original data file. Besides, in fact our simultaneous privately and publicly verifiable scheme can also be adjusted to elliptic curve group. The scheme proposed is efficient on both client and server sides, especially in computation on cloud server side, which is almost optimal among those existing publicly verifiable schemes. Here the server needs not to perform any exponent operations at all, which greatly reduces client's waiting time. Finally, we make the security analysis of our scheme under several cryptographic assumptions, such as difficulty of Factorization Assumption and Discrete Logarithm Problem (DLP).