Proof of retrievability based on LDPC codes

In order to reduce the computational overhead of proof of retrievability (POR) scheme, a new POR scheme based on low-density parity-check (LDPC) codes is proposed, noted as LDPC-POR. In the model of PORs scheme, the client preprocesses the data and sends it to an untrusted server for storage, only keeping some metadata. Then, the client sends a challenge to the server to prove that the data stored at the server has neither been tampered nor deleted. In the setup phase of this scheme, the client uses LDPC code to encode the data, and blinds data with permutation and pseudo-random stream. In the challenge phase, the server generates the proof completely based on exclusive OR (XOR), after that the client makes use of the LDPC code to prove the validity of proof. The theoretical analysis shows that this scheme not only reduces the computational overhead, but also saves storage space compared with the classical scheme. In the meantime security proof is also provided in this paper showing that this scheme is feasible.