Provable Secure Escrow-Free Identity-Based Signature Scheme for Smart City Environment

Abstract Smart city is a concept of digitalizing the ecosystem to solve many urban area issues such as crime reduction, transportation, waste management, and governance. However, the security and threat-related issues are still neglected. This paper presents a secure smart city framework using an identity-based signature (IBS) scheme. It is challenging to employ IBS for a smart city (a large network size) due to its key escrow nature. So, we first proposed an identity-based signature scheme that mitigates the trust on a single private key generator (PKG) by employing multiple authorities to preserve the privacy of user’s private key via threshold cryptography. The system also offloads the key protection overhead to the multiple edge gateway, making the system as efficient as the generic IBS. We demonstrate the proposed scheme is secured against the following required attacks: forgeable attack, user slander attacks, and key abusing attacks assuming the computational Diffie-Hellman problem (CDHP) in the random oracle model (ROM). Additionally, the proposed system allows the recipient to verify multiple message-signature pairs at the least cost. The performance analysis determines the optimal signature size and least computational cost compared to related systems making the proposed system suitable for implementing a secure smart city.