How can we find the minimum number of differentially active s-boxes in a block cipher (actually a Feistel network with several input cells) in a truncated characteristic form? In a recursive algorithm when we get to the situation that there are binary cases, I don't know what to do? For example when I get a xor of two nonzero characteristics, there are two cases nonzero and zero, How can recursive algorithm be applied in this state?
There many methods to find the number of active sboxes such as:
search algorithm , you input different scenarios , it is time-expensive process.
Matsui algorithm. code
Mixed integer linear programming.
I recommend you to try MIxed integer linear programming