A signature scheme is one of the important primitives in modern cryptography, which may offer functionalities of user identification, non‐repudiation, and message authentication. With the advent of identity (ID)‐based public key systems with bilinear pairings defined on elliptic curves, many ID‐based signature schemes have been proposed. Like certificate‐based public key systems, any ID‐based public key system must provide a revocation method to revoke misbehaving users. There was little work on studying the revocation problem of ID‐based public key systems, and no ID‐based signature scheme deals with how to revoke the signing ability of misbehaving users. Quite recently, Tseng and Tsai presented a practical revocation mechanism using a public channel for ID‐based public key systems. In this paper, we adopt Tseng and Tsai's revocation concept to define the new framework and security notions of revocable ID‐based signature (RIBS) scheme and propose the first RIBS scheme in the standard model. Under the computational Diffie–Hellman assumption, we demonstrate that the proposed RIBS scheme is provably secure while remaining efficient for signing and verification as compared with previously proposed ID‐based signature schemes. Copyright © 2013 John Wiley & Sons, Ltd.
Certificateless public key cryptography is very attractive in solving the key escrow problem which is inherent in identity- (ID-) based public key cryptography. In the past, a large number of certificateless cryptographic schemes and protocols were presented, but a secure certificateless signature in the standard model (without random oracles) is still not accessible until now. To the best of our knowledge, all the previously proposed certificateless signature schemes were insecure under a considerably strong security model in the sense that they suffered from outsiders’ key replacement attacks or the attacks from the key generation center (KGC). In this paper, we propose a certificateless signature scheme without random oracles. Moreover, our scheme is secure under the strong security model and provides a public revocation mechanism, called revocable certificateless signature (RCLS). Under the standard computational Diffie-Hellman assumption, we formally demonstrate that our scheme possesses existential unforgeability against adaptive chosen-message attacks.
In 2012, Tseng and Tsai presented a novel revocable ID (identity)-based public key setting that provides an efficient revocation mechanism with a public channel to revoke misbehaving or compromised users from public key systems. Subsequently, based on Tseng and Tsai's revocable ID-based public key setting, Tsai et al. proposed a new revocable ID-based signature (RIBS) scheme in the standard model (without random oracles). However, their RIBS scheme possesses only existential unforgeability under adaptive chosen-message attacks. In the article, we propose the first strongly secure RIBS scheme without random oracles under the computational Diffie-Hellman and collision resistant assumptions. Comparisons with previously proposed schemes are made to demonstrate the advantages of our scheme in terms of revocable functionality and security property.
Certificateless public-key systems (CL-PKS) were introduced to simultaneously solve two critical problems in public-key systems. One is the key escrow problem in ID-based public-key systems and the other is to eliminate the presence of certificates in conventional public-key systems. In the last decade, several certificateless signature (CLS) schemes have been proposed in the random oracle model. These CLS schemes possess existential unforgeability against adaptive chosenmessage attacks, and only few of them possess strong unforgeability. A CLS scheme with strong unforgeability plays an important role in the construction of certificateless cryptographic schemes. Unfortunately, all the existing CLS schemes in the standard model (without random oracles) have been shown insecure to provide existential unforgeability under a generally adopted security model. In the article, we propose a strongly secure CLS scheme in the standard model under the generally adopted security model. Our scheme possesses not only existential unforgeability but also strong unforgeability, and turns out to be the first strongly secure CLS scheme in the standard model. Under the collision resistant hash (CRH) and computational Diffie-Hellman (CDH) assumptions, we prove that our CLS scheme possesses strong unforgeability against both Type I (outsiders) and Type II (key generation center) adversaries.
The existence of malicious participants is a major threat for authenticated group key exchange (AGKE) protocols. Typically, there are two detecting ways (passive and active) to resist malicious participants in AGKE protocols. In 2012, the revocable identity- (ID-) based public key system (R-IDPKS) was proposed to solve the revocation problem in the ID-based public key system (IDPKS). Afterwards, based on the R-IDPKS, Wu et al. proposed a revocable ID-based AGKE (RID-AGKE) protocol, which adopted a passive detecting way to resist malicious participants. However, it needs three rounds and cannot identify malicious participants. In this paper, we fuse a noninteractive confirmed computation technique to propose the first two-round RID-AGKE protocol with identifying malicious participants, which is an active detecting way. We demonstrate that our protocol is a provably secure AGKE protocol with forward secrecy and can identify malicious participants. When compared with the recently proposed ID/RID-AGKE protocols, our protocol possesses better performance and more robust security properties.
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