Improved AB-CPREs with HRA Security
Yu Zhang, Yang Wang, Mingqiang Wang · 2023
Attribute-based conditional proxy re-encryption (AB-CPRE) schemes offer flexible controls over delegations of decryption rights, and offer an efficient solution for enforcing access control on outsourced encrypted datum. Recently, Liang et al. proposed the first lattice-based AB-CPREs with selective attribute security against chosen-plaintext attacks (CPA) in ESORICS 2021. In this paper, we first show how to construct a CPA secure AB-CPRE scheme which is suitable for circuits in NC $^{1}$ with polynomially bounded parameters. By contrast, schemes proposed by Liang et al. are only suitable for circuits in NC $^{0}$ with similar parameters. We then show how to convert our CPA secure AB-CPREs to be secure against honest re-encryption attacks (HRA) under a more reasonable definition. We could show that the CPA security and the HRA security of our schemes are based on standard LWE assumptions for suitable parameters in the standard model.