Recently, Xiong et al. and Selvi et al. proposed a certificateless signature scheme secure in the standard model and a certificateless multi-receiver signcryption scheme secure in the random oracle model, respectively. In this paper, we show that they are insecure against malicious-butpassive KGC attacks. More specifically, the former does not achieve unforgeability and the latter does not satisfy confidentiality against type II adversaries.

Vercauteren introduced the concept of optimal pairing, which by definition can be computed by using at most (log₂ r)/φ(k) + log₂ k basic Miller iterations, where r is the order of the groups involved and k is the embedding degree Vercauteren (IEEE Trans Inf Theory 56(1):455–461, 2010). Freeman et al. summarized and proposed all of the new constructions of pairing-friendly elliptic curves that currently exist Freeman et al. (J Cryptol 23(2):224–280, 2010). In this paper, we give an optimal pairing for each family of pairing-friendly curves in Freeman et al. (J Cryptol 23(2):224–280, 2010) by taking the Ate or R-ate pairing approach.

 In this paper, we show that a verifier-based password authentication scheme and two remote user authentication schemes are insecure against several active attacks. These results demonstrate that no more password authentication schemes should be constructed with such ad-hoc methods, i.e, the formal design methodology using provable security should be employed.

A proxy signature enables an original signer to delegate its signing capability to a proxy signer and the proxy signer can sign a message on behalf of the original signer. Later, anyone can verify the validity of proxy signatures. The “public-verifiable” property of the proxy signature is not suitable in some applications in which a proxy signed message may be personally or commercially sensitive. A designated verifier proxy signature scheme is suitable for these environments. In this paper, we propose a provably secure short designated verifier proxy signature scheme in the random oracle model under the Bilinear Diffie–Hellman

In ICISC 2007, Comuta and others showed that among the methods for constructing pairing­friendly curves, those using cyclotomic polynomials, that is, the Brezing­Weng method and the Freeman­Scott­Teske method, are affected by Cheon's algorithm. This paper proposes a method for searching parameters of pairing­friendly elliptic curves that induces minimal security loss by Cheon's algorithm. We also provide a sample set of parameters of BN­curves, FST­curves, and KSS­curves for pairing­based cryptography.

Certificateless cryptography eliminates the need of certificates in public key cryptosystems and solves the inherent key escrow problem in identity-based cryptosystems. An aggregate signature scheme is a signature scheme which allows to aggregate n signatures on n distinct messages from n distinct users into a single signature. Recently, Zhang and Zhang proposed a certificateless aggregate signature scheme provably secure in the random oracle model under the Computational Diffie-Hellman assumption. In this paper, we propose a novel fundamental security requirement for certificateless aggregate signature schemes, called coalition resistance, by presenting coalition attacks on Zhang-Zhang's scheme.

The use of radio frequency identification (RFID) has become widespread in a range of applications. International standards of RFID technology are actively being developed for securing RFID communications. Recently, ISO/IEC WD 29167-6 proposed three security protocols, namely Protocol 1, 2 and 3. In this letter, we show that Protocol 1 - mutual authentication and secure communication in security mode - is vulnerable to a man-in-the-middle attack. We also propose a countermeasure against the attack.

We explore how the topology of spacetime fabric is encoded into the local structure of Riemannian metrics using
the gauge theory formulation of Euclidean gravity. In part I, we provide a rigorous mathematical foundation to
prove that a general Einstein manifold arises as the sum of SU(2)_L Yang-Mills instantons and SU(2)_R anti-
instantons where SU(2)_L and SU(2)_R are normal subgroups of the four-dimensional Lorentz group Spin(4) =
SU(2)_L x SU(2)_R. Our proof relies only on the general properties in four dimensions: The Lorentz group
Spin(4) is isomorphic to SU(2)_L x SU(2)_R and the six-dimensional vector space of two-forms splits canonically
into the sum of three-dimensional vector spaces of self-dual and anti-self-dual two-forms. Consolidating these
two, it turns out that the splitting of Spin(4) is deeply correlated with the decomposition of two-forms on four-
manifold which occupies a central position in the theory of four-manifolds.