In this work a scheme for key distribution and network access in a Wireless Sensor Network (WSN) that utilises Identity- Based Cryptography (IBC) is presented. The scheme is analysed on the ARM920T processor and measurements were taken for the run time and energy of its components. It was found that the Tate pairing component of the scheme consumes significant amounts of energy, and so should be ported to hardware. An accelerator was implemented in 65nm Complementary Metal Oxide Silicon (CMOS) technology and area, timing and energy figures have been obtained for the design. Results indicate that a hardware implementation of IBC would meet the strict energy constraint required of a wireless sensor network node.