Paper 2026/473

PIKE: Faster Isogeny-Based Public Key Encryption with Pairing-Assisted Decryption

Mingjie Chen, KU Leuven, Belgium

Yi-Fu Lai, KU Leuven, Belgium

Kaizhan Lin, College of Computer Science and Artificial Intelligence, Fudan University, Shanghai, China

Abstract

Recent work at Eurocrypt 2025 by Basso and Maino introduced POKÉ, an isogeny-based public key encryption (PKE) scheme. POKÉ shows how two parties can derive a shared secret on a higher-dimensional, SIDH-like commutative diagram via basis evaluations, giving the fastest isogeny-based PKE to date with performance comparable to the original SIDH. In this paper we present PIKE, a new isogeny-based PKE obtained by tweaking the POKÉ design. Our key change is to use pairings to derive the shared secret while preserving post-quantum security. This brings two benefits: (i) decryption is directly faster, and (ii) by relaxing the required prime form, we can choose smaller primes, further improving overall runtime. We provide a proof-of-concept implementation in SageMath. Under the NIST~I setting, our benchmarks show speedups of $1.30\times$ (key generation), $1.24\times$ (encryption), and $1.47\times$ (decryption) over POKÉ, while maintaining competitive public key and ciphertext sizes. In addition, we provide a C implementation. The encryption and decryption take 53~Mcycles (23~ms) and 34~Mcycles (15~ms) on an Intel i7 2.3 GHz CPU, respectively.

@misc{cryptoeprint:2026/473,
      author = {Shiping Cai and Mingjie Chen and Yi-Fu Lai and Kaizhan Lin},
      title = {{PIKE}: Faster Isogeny-Based Public Key Encryption with Pairing-Assisted Decryption},
      howpublished = {Cryptology {ePrint} Archive, Paper 2026/473},
      year = {2026},
      url = {https://eprint.iacr.org/2026/473}
}