CryptoDB
On Instantiating Unleveled Fully-Homomorphic Signatures from Falsifiable Assumptions
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| Presentation: | Slides |
| Conference: | PKC 2024 |
| Abstract: | We build the first unleveled fully homomorphic signature scheme in the standard model. Our scheme is not constrained by any a-priori bound on the depth of the functions that can be homomorphically evaluated, and relies on subexponentially-secure indistinguishability obfuscation, fully-homomorphic encryption and a non-interactive zero-knowledge (NIZK) proof system with composable zero-knowledge. Our scheme is also the first to satisfy the strong security notion of context-hiding for an unbounded number of levels, ensuring that signatures computed homomorphically do not leak the original messages from which they were computed. All building blocks are instantiable from falsifiable assumptions in the standard model, avoiding the need for knowledge assumptions. Conceptually, the main difficulty overcome by our techniques concerns bootstrapping, which is a crucial tool for obtaining unleveled fully homomorphic encryption (FHE). No equivalent technique exists for homomorphic signatures, which is why constructing unleveled fully homomorphic signature schemes has proven elusive until now. |
BibTeX
@inproceedings{pkc-2024-33803,
title={On Instantiating Unleveled Fully-Homomorphic Signatures from Falsifiable Assumptions},
publisher={Springer-Verlag},
author={Romain Gay and Bogdan Ursu},
year=2024
}