Lightweight Certificateless Signcryption Scheme Using Type-3 Pairing on Elliptic Curve

A certificate-based public key cryptosystem has been developed to solve key escrow problems in ID-based public key cryptography, and to remove computational operations for certificate management. Signcryption is a primitive cryptographic that enables signing and encryption to be done in a one step, improving performance by reducing computational loads and communication overheads. Recent research has suggested some pairing-based cryptographic protocols for public key cryptosystems. However, most use Type-1 pairings, which weaken system security by using supersingular elliptic curves over a finite field of characteristics 2 and 3, making them totally unsafe against new attacks designed for Discrete Logarithm Problems. Furthermore, Type-1 pairings that use supersingular elliptic curves over finite fields of massive characteristics are highly inefficient compared to Type-3 pairings. This work proposes a secure and efficient online/offline trade-off scheme based on Type-3 pairings. The safety of the suggested scheme is asserted according to confidentiality and unforgeability based on a random oracle model. Moreover, the efficiency of the proposed approach is evaluated and compared with Type-2 and Type-4 pairings.