Paper 2016/164
Sanitization of FHE Ciphertexts
Léo Ducas and Damien Stehle
Abstract
By definition, fully homomorphic encryption (FHE) schemes support homomorphic decryption, and all known FHE constructions are bootstrapped from a Somewhat Homomorphic Encryption (SHE) scheme via this technique. Additionally, when a public key is provided, ciphertexts are also re-randomizable, e.g., by adding to them fresh encryptions of 0. From those two operations we devise an algorithm to sanitize a ciphertext, by making its distribution canonical. In particular, the distribution of the ciphertext does not depend on the circuit that led to it via homomorphic evaluation, thus providing circuit privacy in the honest-but-curious model. Unlike the previous approach based on noise flooding, our approach does not degrade much the security/efficiency trade-off of the underlying FHE. The technique can be applied to all lattice-based FHE proposed so far, without substantially affecting their concrete parameters.
Metadata
- Available format(s)
- Category
- Public-key cryptography
- Publication info
- Published by the IACR in EUROCRYPT 2016
- Contact author(s)
- damien stehle @ gmail com
- History
- 2016-02-19: received
- Short URL
- https://ia.cr/2016/164
- License
-
CC BY
BibTeX
@misc{cryptoeprint:2016/164, author = {Léo Ducas and Damien Stehle}, title = {Sanitization of {FHE} Ciphertexts}, howpublished = {Cryptology {ePrint} Archive, Paper 2016/164}, year = {2016}, url = {https://eprint.iacr.org/2016/164} }