Cryptanalysis and improvement of a distributed zero trust scheme for airborne wireless sensor networks.

The advancement of airborne wireless sensor networks (AWSNs) in modern aircraft monitoring has introduced heightened risks to security isolation, particularly from insider threats. Namely, the bidirectional real-time data flows enable attackers to hijack vulnerable nodes as gateways to breach both aircraft control systems and airline operational domains, potentially leading to data exfiltration or system sabotage. To address the issue, more recently, a decentralized zero trust framework for AWSNs has been designed, which is centered on a certificateless aggregation signcryption (CLASC) scheme. Unfortunately, through a concrete security attack, we find that the underlying CLASC scheme is insecure against a public-key replacement attacker. In particular, an attacker can successfully forge a valid signature on any false message, thus destroying unforgeability, one of the most important security features a CLASC scheme must provide. Therefore, the existing design cannot achieve its goal. To tackle this problem, we design a security-enhanced CLASC scheme and prove its security under standard security assumptions. We also analyze its practical performance by comparing the computational and communication costs with several related works. By replacing the insecure CLASC scheme, we obtain a security-enhanced distributed zero trust framework for AWSNs.