Improvement of quadratic residues based scheme for authentication and privacy in mobile RFID

The way of transmitting data untouched through radio-frequency of magnetic fields done through wireless, is called RFID (Radio-frequency identification). The purpose of this method is auto identification of objects through tags attached to them. RFID system is created to ease data transfer about objects. An economic transfer was one of early goals of RFID systems, and this useful technology has entered other sectors of industry as well. Yet main concern in RFID systems is security and privacy. So far many protocols have been proposed to authenticate tags and readers but most of them are vulnerable. In year 2013, R. Doss et al. presented a low-weight protocol based on quadratic residues which provides secure channels between tag-reader and reader-server. In this paper we show that this protocol is vulnerable to replay attack and reader impersonation, and an attacker can authenticate itself to server as a legal tag or legal reader. So in this paper an improvement of this protocol is presented that is resistant to these attacks. Moreover, the proposed method has high speed and performance to do modular operations, because of the use of Montgo mery method.