Enhancing RFID Search Protocols based on Counters

RFID(Radio Frequency IDentification) search protocols introduced by Tan et al. are different from common RFID authentication protocols. In a search protocol, RFID reader uses a designated query to find out a desired tag. Recently, Kim et al. proposed efficient RFID search protocols using counters. Using counters to provide freshness is a novel mechanism in RFID protocols which was possible due to the fundamental characteristics of RFID search protocols. However, one demerit of their protocols is that the values of the counters are exchanged in clear which may affect the privacy of tags. In this paper, we show that the values of counters can be hidden. Moreover, we remove redundant steps from the protocols to increase the efficiency of the protocol.