Efficient implementation of elliptic curve cryptography in wireless sensors

Abstract

The deployment of cryptography in sensor networks is a challenging task, given the limited computational power and the resource-constrainednature of the sensoring devices. This paper presents the implementation ofelliptic curve cryptography in the MICAz Mote, a popular sensor platform.We present optimization techniques for arithmetic in binary fields, includingsquaring, multiplication and modular reduction at two different security levels.Our implementation of field multiplication and modular reduction algorithmsfocuses on the reduction of memory accesses and appears as the fastest resultfor this platform. Finite field arithmetic was implemented in C and Assemblyand elliptic curve arithmetic was implemented in Koblitz and generic binarycurves. We illustrate the performance of our implementation with timings forkey agreement and digital signature protocols. In particular, a key agreementcan be computed in 0.40 seconds and a digital signature can be computed andverified in 1 second at the 163-bit security level. Our results strongly indicatethat binary curves are the most efficient alternative for the implementation ofelliptic curve cryptography in this platform.