  We present a memristive device based R$ ^3 $PUF construction achieving highly
desired PUF properties, which are not offered by most current PUF designs: (1)
High reliability, almost 100\% that is crucial for PUF-based cryptographic key
generations, significantly reducing, or even eliminating the expensive overhead
of on-chip error correction logic and the associated helper on-chip data
storage or off-chip storage and transfer. (2) Reconfigurability, while current
PUF designs rarely exhibit such an attractive property. We validate our R$ ^3
$PUF via extensive Monte-Carlo simulations in Cadence based on parameters of
real devices. The R$ ^3 $PUF is simple, cost-effective and easy to manage
compared to other PUF constructions exhibiting high reliability or
reconfigurability. None of previous PUF constructions is able to provide both
desired high reliability and reconfigurability concurrently.
