CryptoDB
On the Black-Box Complexity of Private-Key Inner-Product Functional Encryption
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| Conference: | TCC 2024 |
| Abstract: | We initiate the study of the black-box complexity of private- key functional encryption (FE). Of central importance in the private-key setting is the inner-product functionality, which is currently only known from assumptions that imply public-key encryption, such as Decisional Diffie-Hellman or Learning-with-Errors. As our main result, we rule out black-box constructions of private-key inner-product FE from random oracles. This implies a black-box separation between private-key inner- product FE from all symmetric-key primitives implied by random oracles (e.g., symmetric-key encryption, collision-resistant hash functions). Proving lower bounds for private-key functional encryption schemes introduces challenges that were absent in prior works. In particular, the combinatorial techniques developed by prior works for proving black-box lower bounds are only useful in the public-key setting and predicate encryption settings, which all fail for the private-key FE case. Our work develops novel combinatorial techniques based on Fourier analysis to overcome these barriers. We expect these techniques to be widely useful in future research in this area. |
BibTeX
@inproceedings{tcc-2024-34787,
title={On the Black-Box Complexity of Private-Key Inner-Product Functional Encryption},
publisher={Springer-Verlag},
author={Mohammad Hajiabadi and Roman Langrehr and Adam O'Neill and Mingyuan Wang},
year=2024
}