Paper 2024/1765

Compact and Tightly Secure (Anonymous) IBE from Module LWE in the QROM

Junji Shikata, Yokohama National University

Abstract

We present a new compact and tightly secure (anonymous) identity-based encryption (IBE) scheme based on the module learning with errors (MLWE) assumption, known as the standard lattice assumption, in the (quantum) random oracle model. Our IBE scheme is the first to achieve the asymptotically most compact and tight security under the standard lattice assumption. We design our IBE scheme by instantiating the framework of Gentry, Peikert, and Vaikuntanathan (STOC`08) using the compact trapdoor proposed by Yu, Jia, and Wang (CRYPTO'23). The tightness of our IBE scheme is achieved by extending the proof technique of Katsumata et al. (ASIACRYPT'18, JoC'21) to the Hermite normal form setting. To achieve this, we develop some new results on module lattices that may be of independent interest.

Note: Revised the parameter conditions and others.

@misc{cryptoeprint:2024/1765,
      author = {Toi Tomita and Junji Shikata},
      title = {Compact and Tightly Secure (Anonymous) {IBE} from Module {LWE} in the {QROM}},
      howpublished = {Cryptology {ePrint} Archive, Paper 2024/1765},
      year = {2024},
      url = {https://eprint.iacr.org/2024/1765}
}