Signcryption in a Quantum World

François Gérard, Keno Merckx

Shingo Sato, Junji Shikata

Xiaojun Zhang, Chunxiang Xu, Chunhua Jin +1 more

Proxy-signcryption is a variation of an ordinary signcryption scheme and has been used in many applications where the delegation of rights is quite common. In a proxy-signcryption scheme, an original signcrypter needs to delegate his signcryption capability to a proxy signcrypter to signcrypt messages on behalf of the original signcrypter. By combining the functionalities of proxy signature with identity-based signcryption, in this paper, we propose a novel identity-based proxy-signcryption scheme (IBPSC) from lattice assumptions in the random oracle model. Meanwhile, the security requirements of our IBPSC scheme have been analysed, and our scheme can even resist quantum computer attacks. Compared with existing IBPSC schemes, our scheme is more secure and more efficient. To the best of our knowledge, there is still no relevant IBPSC scheme based on lattice, which is an interesting stepping stone in the post-quantum cryptographic communication.

Gilles Brassard A

Fenghe Wang, Yupu Hu, Chunxiao Wang

Motivated by the demand to have secure signcryption scheme, even in quantum era, the concept of signcryption tag-KEM (key encapsulation machine) is extended to lattice cryptography in this paper. A lattice-based hybrid signcryption scheme is proposed by building a lattice-based signcryption tag-KEM. Based on the hardness of the learning with errors problem and the short integer solution problem, the proposed hybrid signcryption is provable secure in the random oracle model. Furthermore, according to the quantum intractability assumption about lattice problem, the proposed hybrid signcryption scheme is secure even on quantum computers.

Siqi Yu, Mengxue Shang, Fengyin Li

Ensuring the security of transmitted content is an important task in network communication. Signcryption technology combines signature and encryption operations in a single step to achieve message authentication and confidentiality. In practical applications, users are usually in different cryptographic systems, the ordinary signcryption technology cannot realize communication between two different cryptographic systems. And the ciphertext structure of the existing signcryption schemes is relatively complex, signcryption is not efficient. Therefore, in order to solve the problem of efficient communication between different cryptosystems and ensure quantum security, this paper proposes a lattice-based efficient heterogeneous signcryption scheme for secure network communications. This signcryption scheme accomplishes signcryption through matrix operations and hash functions, which avoids complex signcryption structures, efficiently realizes bidirectional message communication between identity-based cryptosystems and certificateless cryptosystems.