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Low Communication Threshold Fully Homomorphic Encryption
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| Conference: | ASIACRYPT 2024 |
| Abstract: | We study constructions of threshold fully homomorphic encryption with small partial decryption shares. In this context, we discuss in details the technicalities for achieving full-fledged threshold FHE, and bring light to limitations regarding prior works, inclucing an attack against the recent construction from Boudgoust and Scholl [ASIACRYPT 2023]. In light of our observations, we generalize the definition of threshold fully homomorphic encryption by adding an algorithm which allows to sanitize evaluated ciphertexts before they are decrypted by parties. In this setting, we are able to propose a construction which offers small partial decryption shares and avoids exponential noise flooding during partial decryption. In addition, we also propose an alternative protocol based on circuit-private (non-threshold) FHE and threshold public-key encryption for private delegation of computation on joint data, but requires an additional round of communication compared to our threshold FHE construction. |
BibTeX
@inproceedings{asiacrypt-2024-34664,
title={Low Communication Threshold Fully Homomorphic Encryption},
publisher={Springer-Verlag},
author={Alain Passelègue and Damien Stehlé},
year=2024
}