On RFID authentication protocols with wide-strong privacy

Radio frequency identification (RFID) tag privacy is an important issue to RFID security. To date, there have been several attempts to achieve the wide-strong privacy by using zero-knowledge protocols. In this paper, we launch an attack on the recent zero-knowledge based identification protocol for RFID, which was claimed to capture wide-strong privacy, and show that this protocol is flawed. Subsequently, we propose two zero-knowledge based tag authentication protocols and prove that they offer wide-strong privacy.