# Tag Info

To know how many boolean functions you got you have to look at the output of the S-Box... A $N \times M$ S-Box gives you $M$ functions. In the example you passed, you have a function $f_1$ given by $00 \rightarrow 0\\ 01 \rightarrow 1\\ 10 \rightarrow 0\\ 11 \rightarrow 1$ and a function $f_2$ given by $00 \rightarrow 1\\ 01 \rightarrow 1\\ 10 ... 3 Your n x n S-Box can be seen as a set of$ n $boolean vectors of size$ n $. Actually you have got$ n \$ functions, each one is the truth table of one particular vector (or column). In your example there are 2 columns thus 2 functions. For each column the number of 1's is 2.