Vulnerabilities in a new RFID access control protocol

Recently Chen et al. have proposed a RFID access control protocol based on the strategy of indefinite-index and challenge-response. They have claimed that their protocol provides optimal location privacy and resists against man in the middle, spoofed tag and spoofed reader attacks. However, in this paper we show that Chen et al. protocol does not provide the claimed security. More precisely, we present the following attacks on the protocol: 1) Tag impersonation attack. 2) Reader impersonation attack. 3) Location traceability attack. All attacks presented in this paper have the success probability of `1´ on the cost of only one or two runs of protocol.