An efficient identity-based proxy signcryption using lattice

Abstract

Signcryption combines the functionalities of digital signature and encryption in a single step, which promises to increase the efficiency and the confidentiality of on-line transactions. Identity-based proxy signcryption integrates the functions of identity-based cryptography, proxy signature and signcryption. However, identity-based proxy signcryption constructed on the discrete logarithm and the integer factoring problems cannot defeat quantum attack. Therefore, the paper proposes a lattice-based identity-based proxy signcryption since there are none efficient quantum algorithms to attack lattice-based cryptography. The constructed scheme has the properties of both signcryption and proxy signature, i.e., the constructed scheme has ind-cca2 security, suf-cma security, strong identifiability, strong undeniability and key dependence properties. Comparing with the known identity-based proxy signcryption, the proposed scheme needs smaller computation complexity, smaller secret key size and smaller signature tuple size. Besides, the proposed scheme does not depend on the public key infrastructure since it is an identity-based cryptography.