PSPF-IBAS: A Provably Secure Pairing-Free Identity-Based Aggregate Signature Scheme

Recently, Cheng et al. proposed a privacy-preserving and reliable trust-aware platoon recommendation (PPRT) scheme. The PPRT scheme adopts a pairing-free identity-based aggregate signature scheme (PF-IBAS) to ensure existential unforgeability. We demonstrate that the PPRT scheme is insecure in terms of unforgeability. We construct a concrete chosenmessage attack on it. Our attack forges a signature in under 34 minutes on a standard laptop. To address this issue, we propose a provably secure PF-IBAS (PSPF-IBAS) scheme. Security analysis proves that the PSPF-IBAS scheme provides provable security guarantees against the aforementioned attacks. Experiments show that PSPF-IBAS outperforms pairing-based alternatives by eliminating costly pairing operations, achieving superior efficiency in both signing and verification for moderatescale IoV deployments with up to 202 vehicles.