1. imec-COSIC , Department of Electrical Engineering , KU Leuven , Kasteelpark Arenberg 10/2452, 3001 Leuven (Heverlee); and Department of Mathematics: Algebra and Geometry, Ghent University, Krijgslaan 281/S25, 9000 Gent , Belgium
2. Section of Algebra , Department of Mathematics , KU Leuven , Celestijnenlaan 200B, 3001 Leuven (Heverlee) , Belgium
3. School of Science , Westlake University , 18 Shilongshan Rd., Cloud Town, Xihu District , Hangzhou , Zhejiang 310024 , P. R. China