Abstract. Cloud computing is a new computing paradigm that is gaining increased popularity. More and more sensitive user data are stored in the cloud. The privacy of users’ access pattern to the data should be protected to prevent un-trusted cloud servers from inferring users’ private information or launching stealthy attacks. Meanwhile, the privacy protection schemes should be efficient as cloud users often use thin client devices to access the cloud. In this paper, we propose a lightweight scheme to protect the privacy of data access pattern. Comparing with existing state-of-the-art solutions, our scheme incurs less communication and computational overhead, requires significantly less storage space at the cloud user, while consuming similar storage space at the cloud server. Rigorous proofs and extensive evaluations have been conducted to demonstrate that the proposed scheme can hide the data access pattern effectively in the long run after a reasonable number of accesses have ...