An Efficient Pairing-Free Certificateless Signature Scheme with KGC Trust Level 3 for Wireless Sensor Network

With the widespread adoption of wireless sensor networks (WSN), the security of the WSN has been a wide concern. Certificateless signature eliminates the certificate management problem and key escrow problem and is considered a feasible solution to solve the data integrity and authentication of WSN. Recently, Thumbur et al. proposed an efficient pairing-free certificateless signature scheme, and Xu et al. pointed out that their scheme is not resistant to signature forgery attacks and proposed an improved scheme. Based on the trust hierarchy defined by Girault, we find that Xu et al.’s scheme is still only able to achieve security under KGC trust level 2. Moreover, Thumbur et al.’s scheme uses the Schnorr signature algorithm form, which makes it favorable for scaling, while Xu et al.’s scheme breaks this advantage. Therefore, we propose a pairing-free certificateless scheme capable of reaching KGC trust level 3, still using the Schnorr signature algorithm form, and prove the security of the new scheme under the random oracle model. The final efficiency analysis shows that the new scheme has shorter public key length and higher computational efficiency.