A Forward-Secure Certificate-Based Signature Scheme in the Standard Model

Abstract

Abstract.To alleviate the influence of key exposure, we combine forwardsecurity with certificate-based cryptography and give formal definitions and the security model of forward-secure certificate-based signatures. Then we propose a forward-secure certificate-based signature scheme, which is proven to be existentially unforgeable against adaptive chosen message attacks in the standard model. Hence, we partially solve the key exposure problem in certificate-based signature scheme and improve the system security.

A Forward-Secure Certificate-Based Signature Scheme with Enhanced Security in the Standard Model

“…As shown in [27,35], it is very likely to compromise a target's message privacy or signature unforgeability without the knowledge of the corresponding secret key by injecting some malicious trapdoors into the system. In this paper, we demonstrate that Li et al's FS-CBS scheme [38] is insecure under the existential forgery attack from the malicious CA. Our presented attack shows that a CA can easily inject trapdoors into the system and forge valid signatures in the name of any user.…”

“…Our proofs in the standard model demonstrate that it achieves the unforgeability against chosen-message attacks under the complexity assumption of the square computational Diffie-Hellman problem. Compared with Li et al's FS-CBS scheme [38], the enhanced scheme enjoys three advantages. First of all, it can offer stronger safety guarantee for the practical application since it is immune to the existential forgery attack by the malicious CA.…”

“…The goal of this paper is to fix the security vulnerability in the FS-CBS scheme presented by Li et al in [38]. In Li et al's scheme, the CA is supposed to be honest but curious.…”

“…They also provided a generic method to construct the FS-CBE schemes. Subsequently, Li et al [38] put forward the concept of forward-secure CBS (FS-CBS) along with a FS-CBS scheme without random oracles. In the standard model, Li et al proved the security of their scheme under the complexity assumptions of the many Diffie-Hellman (Many-DH) and the generalized computational Diffie-Hellman (GCDH) problems.…”

Provably secure certificate‐based key‐insulated signature scheme

“…Recently, Li et al . proposed a forward‐secure certificate‐based signature scheme, which is proven to be secure in the standard model. The proposed scheme alleviates the influence of key exposure.…”