—Privacy protection is increasingly important during authentications in Radio Frequency Identification (RFID) systems. In order to achieve high-speed authentication in largescale RFID systems, researchers propose tree-based approaches, in which any pair of tags share a number of key components. Such designs, being efficient, often fail to achieve forward secrecy and resistance to attacks, such as compromising and desynchronization. Indeed, these attacks may still take effect even after a tag successfully finishes the authentication and keyupdating procedure. To address the issue, we propose a lightweight RFID private authentication protocol, RWP, based on the random walk concept. RWP also provides the forward security and temporal resistance to the tracking attack. The analysis results show that RWP effectively enhances the security protection for RFID private authentication, and increases the authentication efficiency from O(logN) to O(1). Keywords-RFID; private authentication; rand...