Degree of regularity for HFE
Jíntai Ding, Thorsten Kleinjung · 2011
Abstract. In this paper, we prove a closed formula for the degree of regularity of the family of HFE- (HFE Minus) multivariate public key cryptosystems over a finite field of size q. The degree of regularity of the polynomial system derived from an HFE- system is less than or equal to (q − 1)(⌊logq (D − 1) ⌋ + a) + 2 if q is even and r + a is odd,