Date Added: May 2010
Authentication protocols for Radio Frequency IDentification (RFID) systems allow an RFID reader and a tag to mutually authenticate each other. Numerous protocols have been recently proposed in the literature, and the field is challenging since RFID tags can only work in very confined environments with scarce resources, so protocols should ensure that the underlying computations are not resource intensive. Along this line, a class of ultralight-weight authentication protocols have been proposed. These protocols use only triangular operations, e.g., exclusive OR (XOR), bitwise AND, bitwise NOT, which are very lightweight but, on the other hand, only offer very limited diffusion properties.