Accelerating PEGASUS by Applying NTRU-Based GSW-Like Encryption

Shusaku Uemura, Kazuhide Fukushima

2025

Abstract

Fully homomorphic encryption (FHE) enables to execute operations on ciphertexts without decryption. This leads to an expectation on FHE to be applied to analyses of confidential data. Each of FHE schemes proposed thus far has its own strengths such as an ability to handle real numbers or execute arbitrary functions. Scheme switching enables to switch one FHE ciphertext to another, and enables to utilize both strengths. However, as scheme switching is computationally expensive, it is sometimes more efficient to use one scheme with approximation. Xiang et al. (CRYPTO23) proposed an efficient blind rotation technique which is used in a scheme switching method named PEGASUS. They use the NTRU-based GSW-like encryption to accelerate blind rotation, which can be applied to schemes that use the GSW encryption. This paper investigates the effects of the application of the NTRU-based GSW-like encryption to PEGASUS. We found that applying the NTRU-based GSW-like encryption to PEGASUS theoretically reduces the key size required to evaluate a look-up table by 43% and the number of multiplications of integers by 96%. We also confirmed through experiments that using the NTRU-based GSW-like encryption in PEGASUS accelerates the evaluation of a look-up table by 1.55 times.

Paper Citation

in Harvard Style

Uemura S. and Fukushima K. (2025). Accelerating PEGASUS by Applying NTRU-Based GSW-Like Encryption. In Proceedings of the 22nd International Conference on Security and Cryptography - Volume 1: SECRYPT; ISBN 978-989-758-760-3, SciTePress, pages 650-657. DOI: 10.5220/0013555300003979

in Bibtex Style

@conference{secrypt25,
author={Shusaku Uemura and Kazuhide Fukushima},
title={Accelerating PEGASUS by Applying NTRU-Based GSW-Like Encryption},
booktitle={Proceedings of the 22nd International Conference on Security and Cryptography - Volume 1: SECRYPT},
year={2025},
pages={650-657},
publisher={SciTePress},
organization={INSTICC},
doi={10.5220/0013555300003979},
isbn={978-989-758-760-3},
}

in EndNote Style

TY - CONF

JO - Proceedings of the 22nd International Conference on Security and Cryptography - Volume 1: SECRYPT
TI - Accelerating PEGASUS by Applying NTRU-Based GSW-Like Encryption
SN - 978-989-758-760-3
AU - Uemura S.
AU - Fukushima K.
PY - 2025
SP - 650
EP - 657
DO - 10.5220/0013555300003979
PB - SciTePress