Provably Secure Generic Construction of Certificate Based Signature from Certificateless Signature in Standard Model

Both certificateless cryptography (CLC) and certificate-based cryptography (CBC) are two novel public key paradigms which combine the merits of traditional public key cryptography (PKC) and identity-based cryptography (IBC). They succeed in avoiding the key escrow problem in IBC and reducing the public key management overhead in traditional PKC. This paper deals with the generic construction of certificate based signature (CBS) from certificateless signature (CLS). Wu et al. proposed the first generic conversion from CLS to CBS provably secure in the random oracle model. This paper proposes an intuitive, simple and provably secure generic conversion from CLS to CBS. The security for this conversion is proved in the standard model. To develope the security proof of this conversion, we put forth one novel security model which introduces a previously neglected notrivial attack and better captures the CLS security notion. Following this generic conversion, a provably secure CLS scheme is constructed as an example

An Efficient Certificate-Based Designated Verifier Signature Scheme

Certificate-based public key cryptography not only solves certificate revocation problem in traditional PKI but also overcomes key escrow problem inherent in identity-based cryptosystems. This new primitive has become an attractive cryptographic paradigm. In this paper, we propose the notion and the security model of certificate-based designated verifier signatures (CBDVS). We provide the first construction of CBDVS and prove that our scheme is existentially unforgeable against adaptive chosen message attacks in the random oracle model. Our scheme only needs two pairing operations, and the signature is only one element in the bilinear group G1. To the best of our knowledge, our scheme enjoys shortest signature length with less operation cost

Tight reduction for generic construction of certificateless signature and its instantiation from DDH assumption

Certificateless signature was proposed by Al-Riyami and Paterson to eliminate the certificate management in the public-key infrastructures and solve the key escrow problem in the identity-based signature. In 2007, Hu et al. proposed a generic construction of certificateless signature. They construct certificateless signature scheme from any standard identity-based signature and signature scheme.However, their security reduction is loose; the security of the constructed scheme depends on the number of users. In this paper, we give the tight reduction for their construction and instantiate a tightly-secure certificateless signature scheme without pairing from DDH assumption. Best of our knowledge, this scheme is the first tightly-secure certificateless signature scheme

Certificateless Signature Scheme Based on Rabin Algorithm and Discrete Logarithm

Certificateless signature can effectively immue the key escrow problem in the identity-based signature scheme. But the security of the most certificateless signatures usually depends on only one mathematical hard problem, which makes the signature vulnerable when the underlying hard problem has been broken. In order to strengthen the security, in this paper, a certificateless signature whose security depends on two mathematical hard problems, discrete logarithm and factoring problems, is proposed. Then, the proposed certificateless signature can be proved secure in the random oracle, and only both of the two mathematical hard problems are solved, can the proposed signature be broken. As a consequence, the proposed certificateless signature is more secure than the previous signatures. On the other hand, with the pre-computation of the exponential modular computation, it will save more time in the signature signing phase. And compared with the other schemes of this kind, the proposed scheme is more efficient

Toward an RSU-unavailable lightweight certificateless key agreement scheme for VANETs

Vehicle ad-hoc networks have developed rapidly these years, whose security and privacy issues are always concerned widely. In spite of a remarkable research on their security solutions, but in which there still lacks considerations on how to secure vehicle-to-vehicle communications, particularly when infrastructure is unavailable. In this paper, we propose a lightweight certificateless and one-round key agreement scheme without pairing, and further prove the security of the proposed scheme in the random oracle model. The proposed scheme is expected to not only resist known attacks with less computation cost, but also as an efficient way to relieve the workload of vehicle-to-vehicle authentication, especially in no available infrastructure circumstance. A comprehensive evaluation, including security analysis, efficiency analysis and simulation evaluation, is presented to confirm the security and feasibility of the proposed scheme

Certificateless Proxy Signature from RSA

Although some good results were achieved in speeding up the computation of pairing function in recent years, it is still interesting to design efficient cryptosystems with less bilinear pairing operation. A proxy signature scheme allows a proxy signer to sign messages on behalf of an original signer within a given context. We propose a certificateless proxy signature (CLPS) scheme from RSA and prove its security under the strongest security model where the Type I/II adversary is a super Type I/II adversary

A supplement to Liu et al.\u27s certificateless signcryption scheme in the standard model

Recently, Liu et al. proposed the first certificateless signcryption scheme without random oracles and proved it was semantically secure in the standard model. However, Selvi et al. launched a fatal attack to its confidentiality by replacing users\u27 public keys, thus pointed out this scheme actually doesn\u27t reach the semantic security as claimed. In this paper, we come up with a rescue scheme based on Liu et al.\u27s original proposal. A Schnorr-based one-time signature is added to each user\u27s public key, which is used to resist Selvi et al.\u27s attack. In addition, according to the mistake made in Liu et al.\u27s security proof, we also show that our improvement is really secure in the standard model under the intractability of the decisional bilinear Diffie-Hellman assumption

Strongly Unforgeable Certificateless Signature Resisting Attacks from Malicious-But-Passive KGC

In digital signature, strong unforgeability requires that an attacker cannot forge a new signature on any previously signed/new messages, which is attractive in both theory and practice. Recently, a strongly unforgeable certificateless signature (CLS) scheme without random oracles was presented. In this paper, we firstly show that the scheme fails to achieve strong unforgeability by forging a new signature on a previously signed message under its adversarial model. Then, we point out that the scheme is also vulnerable to the malicious-but-passive key generation center (MKGC) attacks. Finally, we propose an improved strongly unforgeable CLS scheme in the standard model. The improved scheme not only meets the requirement of strong unforgeability but also withstands the MKGC attacks. To the best of our knowledge, we are the first to prove a CLS scheme to be strongly unforgeable against the MKGC attacks without using random oracles