Yupu Hu

Indentity-based broadcast signcryption

Broadcast encryption schemes allow a center to deliver encrypted data to a large set of users so that only a particular subset of privileged users can decrypt it. Most of previous works about broadcast encryption only provide confidentiality of the message. However, when a broadcast system is composed of multiple broadcasters, it raises an issue of authentication and non-repudiation of the message or broadcaster. This issue is especially important for multicasting in computer networks. In this paper, a new concept called broadcast signcryption by combining the concepts of broadcast encryption and signcryption together is proposed to resolve the authentication and non-repudiation problem in a broadcast system. We also propose an identity-based broadcast signcryption scheme using Chen and Malone-Lees identity-based signcryption scheme.

An Identity-Based Signcryption Scheme for Multi-domain Ad Hoc Networks

As various applications of wireless ad hoc networks have been proposed, security has become one of the big research challenges and is receiving increasing attention. Recently, Several security schemes for wireless ad hoc networks have been proposed using identity-based signcryption schemes. However, almost all identity-based signcryption schemes that have been proposed until now are based on a single private key generator, which is not suitable for multi-domain ad hoc networks. In this paper, we propose a new identity-based signcryption scheme based on multiple private key generators, which is more suitable for multi-domain ad hoc networks. We prove its semantical security under the Decisional Bilinear Diffie-Hellman assumption in the random oracle model.

ID-Based Signcryption Scheme with (t,n) Shared Unsigncryption

An identity-based signcryption scheme with (t,n) shared unsigncryption is proposed, which is the integration of the signcryption scheme, the (t,n) threshold scheme and zero knowledge proof for the equality of two discrete logarithms based on the bilinear map. In this scheme, any third party can verify the validity of the signature, but only more than t members in the recipient group can cooperatively recover the message m. As compared to the Zhang et al.s signcryption scheme with (t,n) shared unsigncryption based on discrete logarithms, the proposed scheme has the following advantages: it provides both public verifiability and forward security; the key management problem is simplified because of using identity-based cryptosystem.

Efficient and strongly unforgeable identity-based signature scheme from lattices in the standard model

An identity-based signature scheme from lattices is constructed. The scheme is obtained from a modification of Agrawal, Boneh, and Boyens lattice identity-based encryption scheme. In this construction, we use two distinct trapdoors for finding short bases. One trapdoor enables the real implementation to generate short bases for all lattices. The other trapdoor enables the simulator to generate short bases for all lattices. Furthermore, the generating short bases are used to sample short vectors as signatures. Our scheme is computationally efficient. The schemes strong unforgeability is proven in the standard model and rests on the hardness of the small integer solution problem. Finally, we extend the basic construction to obtain a hierarchical identity-based signature scheme. Copyright

Adaptively secure identity-based broadcast encryption with constant size private keys and ciphertexts from the subgroups☆

Abstract The main challenge in building efficient broadcast systems is to encrypt messages with short ciphertexts. The well-known constructions of identity-based broadcast encryption (IBBE) with constant size ciphertexts in the standard model are based on the non-standard cryptography assumption. In addition, these constructions cannot solve the trade-off between the private keys and ciphertexts. These folklore construction methods lead to schemes that are somewhat inefficient and leave open the problem of finding more efficient direct constructions. In this paper, we give a secure identity-based broadcast encryption scheme with a constant-size ciphertext and private keys. It is constructed by using dual techniques in the subgroups. The proposed scheme achieves the full security (adaptive security) under three static (i.e. non q -based) assumptions. It is worth noting that only recently Waters’s scheme achieves adaptive security under simple assumptions. One feature of our scheme is that it is relatively simple to get adaptive security.

ID-based threshold proxy signcryption scheme from bilinear pairings

A (t, n) threshold proxy signcryption scheme allows t or more proxy signcrypters from a designated group of n proxy signcrypters to signcrypt messages on behalf of an original signcrypter. In this paper, a new identity-based threshold proxy signcryption scheme from bilinear pairings is proposed. Our construction is based on Baek and Zhengs pairing-based verifiable secret sharing scheme and Libert and Quisquaters identity-based signcryption scheme. As compared to Wang and Lius identity-based threshold proxy signcryption scheme, our scheme is more secure and efficient.

New Construction of Short Hierarchical ID-Based Signature in the Standard Model

In this paper, a new construction of hierarchical ID-Based signature (HIBS) scheme is proposed. The new scheme has some advantages over the available schemes: the private keys size shrinks as the identity depth increases and the signature size is a constant as it consists of three group elements. Furthermore, under the h-CDH assumption, our scheme is provably secure in the standard model. This assumption is more natural than many of the hardness assumptions recently introduced to HIBS in the standard model.

ID-Based threshold unsigncryption scheme from pairings

An identity-based threshold unsigncryption scheme is proposed, which is the integration of the signcryption scheme, the (t,n) threshold scheme and zero knowledge proof for the equality of two discrete logarithms based on the bilinear map. In this scheme, a signcrypted message is decrypted only when more than t members join an unsigncryption protocol and the signature can be verified by any third party. A formal proof of security of this scheme is provided in the random oracle model, assuming the Decisional Bilinear Diffie-Hellman problem is computationally hard.

Efficient identity-based signature over NTRU lattice

Identity-based signature has become an important technique for lightweight authentication as soon as it was proposed in 1984. Thereafter, identity-based signature schemes based on the integer factorization problem and discrete logarithm problem were proposed one after another. Nevertheless, the rapid development of quantum computers makes them insecure. Recently, many efforts have been made to construct identity-based signatures over lattice assumptions against attacks in the quantum era. However, their efficiency is not very satisfactory. In this study, an efficient identity-based signature scheme is presented over the number theory research unit (NTRU) lattice assumption. The new scheme is more efficient than other lattice- and identity-based signature schemes. The new scheme proves to be unforgeable against the adaptively chosen message attack in the random oracle model under the hardness of the γ-shortest vector problem on the NTRU lattice.

Constructions of 1-resilient Boolean functions on odd number of variables with a high nonlinearity

In this paper, we concentrate on the design of 1-resilient Boolean functions with desirable cryptographic properties. Firstly, we put forward a novel secondary construction to obtain 1-resilient functions. Next, we present the relationships between the properties of these constructed 1-resilient functions and that of the initial functions. Based on the construction and a class of bent functions on n variables, we can obtain a class of (n + 3)-variable 1-resilient non-separable cryptographic functions with a high algebraic immunity, whose nonlinearity is equal to the bent concatenation bound 2n + 2 − 2(n + 2)/2. Furthermore, we propose a set of 1-resilient non-separable functions on odd number of variables with an optimal algebraic degree, a high algebraic immunity, and a high nonlinearity. Copyright