Recently, Kianersi et al. have proposed an ultra-lightweight mutual authentication protocol for low-cost RFID tags, entitled SULMA. They have claimed that the SULMA protocol is secure against most of the known attacks for an RFID protocol; includes traceability attack, passive attacks and desynchronization. However, in this paper, we analyse the security of SULMA protocol and present several efficient attacks against this protocol. Our attacks include reader impersonation attack and

more »

... attack. Moreover, we show that the main subcomponent of the protocol called MixBit-function does not satisfy the claimed property.