CryptoDB
Crooked Indifferentiability of the Feistel Construction
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| Presentation: | Slides |
| Conference: | ASIACRYPT 2024 |
| Abstract: | The Feistel construction is a fundamental technique for building pseudorandom permutations and block ciphers. This paper shows that a simple adaptation of the construction is resistant, even to algorithm substitution attacks---that is, adversarial subversion---of the component round functions. Specifically, we establish that a Feistel-based construction with more than $337n/\log(1/\epsilon)$ rounds can transform a subverted random function---which disagrees with the original one at a small fraction (denoted by $\epsilon$) of inputs---into an object that is \emph{crooked-indifferentiable} from a random permutation, even if the adversary is aware of all the randomness used in the transformation. Here, $n$ denotes the length of both the input and output of the round functions that underlie the Feistel cipher. We also provide a lower bound showing that the construction cannot use fewer than $2n/\log(1/\epsilon)$ rounds to achieve crooked-indifferentiable security. |
BibTeX
@inproceedings{asiacrypt-2024-34655,
title={Crooked Indifferentiability of the Feistel Construction},
publisher={Springer-Verlag},
author={Alexander Russell and Qiang Tang and jiadong zhu},
year=2024
}