## CryptoDB

### ByeongHak Lee

#### Publications

Year
Venue
Title
2018
ASIACRYPT
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.

Jooyoung Lee (1)