  Recently, we have witnessed the emergence of intermittently powered
computational devices, an early example is the Intel WISP (Wireless
Identification and Sensing Platform). How we engineer basic security services
to realize mutual authentication, confidentiality and preserve privacy of
information collected, stored and transmitted by, and establish the veracity of
measurements taken from, such devices remain an open challenge; especially for
batteryless and intermittently powered devices. While the cryptographic
community has significantly progressed lightweight (in terms of area overhead)
security primitives for low cost and power efficient hardware implementations,
lightweight software implementations of security primitives for resource
constrained devices are less investigated. Especially, the problem of providing
security for intermittently powered computational devices is unexplored. In
this paper, we illustrate the unique challenges posed by an emerging class of
intermittently powered and energy constrained computational IoT devices for
engineering security solutions. We focus on the construction and evaluation of
a basic hash primitive---both existing cryptographic hash functions and
non-cryptographic hash functions built upon lightweight block ciphers. We
provide software implementation benchmarks for eight primitives on a low power
and resource limited computational device, and outline an execution model for
these primitives under intermittent powering.
