Unbalancing Computations for SM2 Key Exchange Protocols

SM2 is a national ecliptic curve public key algorithm standard promulgated by the State Cryptography Administration (SCA) of China. It contains an authenticated key exchange (AKE) protocol which can establish shared secret keys for two communicating parties. However, the computational burden is generally too heavy for capability-limited devices in Internet of Things (IoT). This paper alleviates its computational burden on limited devices by transferring some time-consuming operations from a limited device to its more powerful communicating partner. Two computationally unbalanced protocols are designed. Compared with the original protocols, the computationally unbalanced protocols are more friendly to limited devices.