How public key cryptography influences wireless sensor node lifetime

In this paper we try to estimate the real influence of public key cryptography (PKC) to the lifetime of a sensor node in wireless sensor networks. We investigate four types of nodes; MICA2DOT, MICA2, MICAz and TelosB. For all these nodes we estimate the power consumption for most common RSA and ECC operations, i.e., signature generation and verification as well as key exchange mechanisms. We also estimate the power consumed by the transmission of their results. Our results show that the application of strong cryptography is feasible. Even for the most constrained node performing the ECC-160 signature once every 10 minutes increases the duty cycle only by about 0.5 per cent, i.e., the influence to the lifetime is not significant. Nevertheless, the public key cryptography shall be used with care.