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Towards Compact Identity-Based Encryption on Ideal Lattices

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Topics in Cryptology – CT-RSA 2024 (CT-RSA 2024)

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Abstract

Basic encryption and signature on lattices have comparable efficiency to their classical counterparts in terms of speed and key size. However, Identity-based Encryption (IBE) on lattices is much less efficient in terms of compactness, even when instantiated on ideal lattices and in the Random Oracle Model (ROM). This is because the underlying preimage sampling algorithm used to extract the users’ secret keys requires huge public parameters. In this work, we specify a compact IBE instantiation for practical use by introducing various optimizations. Specifically, we first propose a modified gadget that offers a tradeoff between security and compactness, making it more suitable for the instantiation of practical IBEs. Then, by incorporating our gadget and the non-spherical Gaussian technique, we provide an efficient preimage sampling algorithm, based on which, we give a specification of a compact IBE on ideal lattice. Finally, two parameter sets and a proof-of-concept implementation are presented. Given the importance of the preimage sampling algorithm in lattice-based cryptography, we believe that our technique can also be applied to the practical instantiation of other advanced cryptographic schemes.

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Acknowledgements

We would like to thank the anonymous reviewers for helpful comments and suggestions. This work is supported by the National Key Research and Development Program of China (Grant No. 2021YFB3100200), the National Natural Science Foundation of China (Grant No. 12171114), the Guangzhou Science and Technology Plan Project (Grant No. 2024A04J3272).

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Authors and Affiliations

  1. School of Mathematics and Information Science, Key Laboratory of Information Security, Guangzhou University, Guangzhou, China

    Huiwen Jia & Chunming Tang

  2. Guangzhou Center for Applied Mathematics, Guangzhou University, Guangzhou, China

    Huiwen Jia & Chunming Tang

  3. State Key Laboratory of Integrated Services Networks, Xidian University, Xi’an, Shaanxi, China

    Yupu Hu

  4. Science and Technology on Communication Security Laboratory, Chengdu, 610041, China

    Lin Wang

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  1. Huiwen Jia
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    Elisabeth Oswald

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Jia, H., Hu, Y., Tang, C., Wang, L. (2024). Towards Compact Identity-Based Encryption on Ideal Lattices. In: Oswald, E. (eds) Topics in Cryptology – CT-RSA 2024. CT-RSA 2024. Lecture Notes in Computer Science, vol 14643. Springer, Cham. https://doi.org/10.1007/978-3-031-58868-6_14

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