Certificateless Signature Revisited

Abstract

Certificate-based encryption was introduced in Eurocrypt'03 to solve the certificate management problem in public key encryption. Recently, this idea was extended to certificate-based signatures. Several new schemes and security models of certificate-based signatures have been proposed. In this paper, we first take a closer look at the certificate-based signature by comparing it with digital signatures in other popular public key systems. We introduce a new security model of certificate-based signature, which defines several new types of adversaries against certificate-based signatures, along with the security model of certificate-based signatures against them. The new model is clearer and more elaborated compared with other existing ones. We then investigate the relationship between certificate-based signatures and certificateless signatures, and propose a generic construction of certificate-based signatures. We prove that the generic construction is secure (in the random oracle model) against all types of adversaries defined in this paper, assuming the underlying certificateless signatures satisfying certain security notions. Based on our generic construction, we are able to construct new certificate-based signature schemes, which are more efficient in comparison with other schemes with similar security levels.

An efficient certificateless blind signature scheme without bilinear pairing

“…A 2 represents a malicious KGC, who cannot replace users' public keys but he could use the master key to generate users' partial private keys. The type adversaries in CLBS could be divided into normal adversary, strong adversary, and super adversary according to their attacks power (Huang et al 2007). In the security analysis of the proposed CLBS scheme, we just need to consider two strongest types of adversaries, i.e.…”

Cryptanalysis on Two Certificateless Signature Schemes

“…Please refer to [1,8,11,13,14] for details. The two original schemes [4,5] are based on bilinear maps.…”

“…Unlike the traditional PKI, there is no certificate in certificateless public key cryptography to ensure the authenticity of the entity's public key. A number of certificateless signature schemes [3][4][5][6][7][8][9][10][11][12][13][14] have been proposed. Some of them are analysed under reasonable security models with elaborate security proofs [8,11,13,14], while some others are subsequently broken due to flawed security proof or unreasonable model [3,[6][7][8]12].…”

Security Analysis of the Certificateless Signature Scheme Proposed at SecUbiq 2006

“…Unfortunately, this modification requires four pairing computations though only two are needed per signature if multiple signatures by the same signer are to be verified. Note that this modification only provides a way to defend our attack, and so does not guarantee the security against other attacks [8]. We provide such an example in the following subsection.…”

“…Besides [1,9], it was shown that certificateless signature schemes in [12] and [13] are insecure against the malicious-but-passive KGC attack [8]. Additionally, the certificateless designated verifier signature scheme proposed by Huang et al is vulnerable to the malicious-but-passive KGC attack as they follow the same system parameters and user key generation procedure as that of [1].…”