Efficient Identity Based Signcryption Scheme with Public Verifiability and Forward Security

In this paper, we point out that Libert and Quisquater’s signcryption scheme cannot provide public verifiability. Then we present a new identity based signcryption scheme using quadratic residue and pairings over elliptic curves. It combines the functionalities of both public verifiability and forward security at the same time. Under the Bilinear Diffie-Hellman and quadratic residue assumption, we describe the new scheme that is more secure and can be some-what more efficient than Libert and Quisquater’s one.

Efficient Hierarchical Identity Based Signature Scheme in the Standard Model

Hierarchical identity based cryptography is a generalization of identity based encryption that mirrors an organizational hierarchy. It allows a root public key generator to distribute the workload by delegating public key generation and identity authentication to lower-level public key generators. Most hierarchical identity based signature schemes are provably secure in the random oracle model or the weak models without random oracles such as gauntlet-ID model. Currently, there is no hierarchical identity based signature scheme that is fully secure in the standard model, with short public parameters and a tight reduction. In this paper, a hierarchical identity based signature scheme based on the q-SDH problem that is fully secure in the standard model is proposed. The signature size is independent of the level of the hierarchy. Moreover, our scheme has short public parameters, high efficiency and a tight reduction.

An Efficient Identity-Based Key Agreement Protocol in a Multiple PKG Environment

Identity-based key agreement protocol affords a natural way to combine the participant＇s identity with its public key. However, most of them just consider the key agreement in a single private key generator （PKG） environment. In addition, the existing key agreement protocols have a great computing overhead for mobile computing which is more and more popular today. This paper proposes a new identity based key agreement protocol. With the help of mathematical tools, we make our protocol applied in multiple PKG environment. It also satisfies all the security properties which is set for key agreement protocol. Moreover, some of its time-consuming operations can be delivered to untrusted public computation resources, so its computing complexity can be greatly reduced.

Cryptanalysis of a Completely Anonymous Multi-recipient Signcryption Scheme with Public Verification

Anonymity is a very important security objective in network communications.Recently,Pang et al.proposed a novel multirecipient signcryption scheme with complete anonymity and claimed that the new concrete scheme was strong existential unforgeability under selective multi-ID,chosen message attack.Unfortunately,by giving concrete attacks,named " inside attack" and " outside attack" respectively,we indicate that Pang et al.'s scheme is not secure in their security model.