HW/SW co-design of Identity-Based Encryption using a custom instruction set

Identity-based cryptography has been gradually accepted as a more effective way of implementing asymmetric cryptography. The calculation of cryptographically-suitable pairings is crucial for the performance of pairing based protocols. In this paper we present a comparative study of hardware implementation techniques for computing the ¿T pairing over the finite field F₃{su97|}. Our hardware-software implementation use Altera Nios II processor as platform. Using code profiling we identify critical field operations which concentrate most of the execution time; then these operations were implemented as specialized FPGA instructions/modules and added to the processor. The specialized processor was synthesized and the application was tailored to the new hardware. Experimental results show that a considerable speedup can be achieved when compared to the baseline software only approach. Moreover, we show that such HW/SW co-design approach is competitive with other solutions.