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Tweakable Block Ciphers Secure Beyond the Birthday Bound in the Ideal Cipher Model
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| Presentation: | Slides |
| Conference: | ASIACRYPT 2018 |
| Abstract: | We propose a new construction of tweakable block ciphers from standard block ciphers. Our construction, dubbed $$\mathsf {XHX2}$$, is the cascade of two independent $$\mathsf {XHX}$$ block ciphers, so it makes two calls to the underlying block cipher using tweak-dependent keys. We prove the security of $$\mathsf {XHX2}$$ up to $$\min \{2^{2(n+m)/3},2^{n+m/2}\}$$ queries (ignoring logarithmic factors) in the ideal cipher model, when the block cipher operates on n-bit blocks using m-bit keys. The $$\mathsf {XHX2}$$ tweakable block cipher is the first construction that achieves beyond-birthday-bound security with respect to the input size of the underlying block cipher in the ideal cipher model. |
BibTeX
@inproceedings{asiacrypt-2018-29146,
title={Tweakable Block Ciphers Secure Beyond the Birthday Bound in the Ideal Cipher Model},
booktitle={Advances in Cryptology – ASIACRYPT 2018},
series={Lecture Notes in Computer Science},
publisher={Springer},
volume={11272},
pages={305-335},
doi={10.1007/978-3-030-03326-2_11},
author={ByeongHak Lee and Jooyoung Lee},
year=2018
}