Score:2

Threshold of resistance against Linear Cryptanalysis

jp flag

In the AES proposal, the last sentence on page 30 it is said:

To be resistant against LC, it is a necessary condition that there are no linear trails with a correlation coefficient higher than 2^(n/2)

I know that the correlation coefficient can have values in the range [-1,1]. Moreover, In the same proposal, they mentioned that

we prove that there are no 4-round linear trails with a correlation above 2^–75

My question is: do they mean "To be resistant against LC, it is a necessary condition that there are no linear trails with a correlation coefficient higher than 2^(-n/2)"

Score:2
sa flag

It is just a simple typo. The whole paragraph from page 30 makes this clear:

enter image description here

It is the correlation that should be no larger than $2^{n/2}$ and the correlation coefficient is obtained by the normalization of the correlation by the maximal value possible, i.e., division by $2^{n}$, thus explaining the reference to $2^{-75}$ elsewhere in the context of correlation coefficient.

I sit in a Tesla and translated this thread with Ai:

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