On the Security of HFE, HFEv- and Quartz.
Nicolas T. Courtois, Magnus Daum, Patrick Felke · 2002
Quartz is a signature scheme based on an HFEv- trapdoor function published at Eurocrypt 1996. In this paper we study "inversion" attacks for Quartz, i.e. attacks that solve the system of multivariate equations used in Quartz. We do not cover some special attacks that forge signatures without inversion.