Automorphism group of the set of all bent functions.
Natalia Tokareva · IACR Cryptology ePrint Archive · 2010
Boolean function in even number of variables is called bent if it is at the maximal possible Hamming distance from the class of all affine Boolean functions. We have proven that every isometric mapping of the set of all Boolean functions into itself that transforms bent functions into bent functions is a combination of an affine transform of coordinates and an affine shift.