A Homomorphic Hashing Based Provable Data Possession

In cloud storage, in order to allow users to verify that the storage service providers store the user's data intactly. A homomorphic hashing based Provable Data Possession (PDP) method is proposed. Because of the homomorphism of hash algorithm, the hash value of the sum of two blocks is equal to the product of the two hash values. It stores all data blocks and their hash values in setup stage. When the user challenges the storage server, the server returns the sum of the requested data blocks and their hash values. The user computes the hash value of the sum of these data blocks and verifies whether they are equal. In the data lifecycle, the user can perform unlimited number of verification. The method provides provable data possession at the same time it provides integrity protection. Users only need to save a key K, about 520 byte, the information transferred for verification only need about 18 bit, and verification only needs one time hash computation. The security and performance analysis show that the method is feasible.