A Practical Accountability Scheme for Oblivious RAM in Cloud Storage

Recently, private information leakage in cloud storage by detecting user's access pattern becomes a hot issue in the security community. Oblivious RAM(ORAM) was proposed to resist this attack. However, the accountability in ORAM is a serious problem because of its oblivious property when consider the malicious user's misbehaves in multi-user cloud storage scenario. Furthermore, based on our observations, the state-of-the-art ORAM design (S-GORAM) has low performance in accountability which also do not support the anonymity. To tackle the above problems, we propose Traceable Oblivious RAM (T-ORAM) which is based on the group signature. Based on our security analysis and simulation experiments, we prove that our scheme outperforms the existing S-GORAM in security and performance of accountability. Moreover, as the byproduct of our design, we also have less storage overhead compared with S-GORAM.