These kinds of protocols are interesting to study because PUFs
and LFSRs are well known lightweight operations that are
very efficient in hardware and particularly suitable for the
low-cost RFID tags. A typical low cost RFID tag in the
literature has 2000 gates available for security operations.
Their protocol require only 784 gates for 64-bit variables.
Therefore, these protocols can certainly be assumed to have
a significant improvement. However, we show that there are
in fact several serious security issues with Kulseng et al.’s
protocols [12].