Efficient and secure heterogeneous aggregate signcryption for Vehicular Ad-Hoc Networks

Vehicular Ad Hoc Networks (VANETs) are an important part of Intelligent Transportation Systems (ITS). They allow vehicles to communicate with each other and with roadside infrastructure to improve traffic flow and road safety. However, because these communications use wireless channels, they are vulnerable to security threats such as message tampering, eavesdropping, and tracking of vehicles. In addition, the use of different cryptographic systems can make communication between networks difficult. To address these issues, this work proposes a pairing-free certificateless heterogeneous aggregate signcryption scheme (PF-CLHASC). The scheme enables secure communication between certificateless cryptography (CLC) and public key infrastructure (PKI) systems without using complex bilinear pairing operations. It also protects vehicle identity by using pseudonyms, preventing messages from being linked to real users. The security of the scheme is based on the hardness of the Elliptic Curve Discrete Logarithm Problem (ECDLP) and is analyzed using the random oracle model. Experimental results show that the scheme reduces computational, communication, and storage costs by 16.67% to 90.33%, and lowers transmission overhead. It also ensures privacy, forward secrecy, and protection against replay, impersonation, and man-in-the-middle attacks.