Boomerang Spectrum of A Class of Power Functions

In EUROCRYPT 2018, Cid et al. introduced a new concept on the cryptographic property of S-boxes to evaluate the subtleties of boomerang-style attacks. This concept was named as boomerang connectivity table (BCT for short). For a power function, the value distribution of BCT can be directly deter-mined by its boomerang spectrum. In this paper, we investigate the boomerang spectrum of a class of power functions over even characteristic finite fields via its differential spectrum, where the exponent is a Niho exponent.