This paper proposes a new group signature scheme derived from a proxy signature scheme which can solve the above problems,and the order of cycle group adopted by this scheme is a public parameter,and the length of group public key is fixed.

The idea making use of producing matrix on the cycle group,this paper has discussed the property about R-grade cycle matrix and the question about R-grade cycle matrix diagonalization,brought to light the relations between one type diagonalization similar matrix and R-grade cycle matrix.

It is prove that groups of order p2 can be divided into two kinds in the isomorphism sense:(1) cycle group;(2)commutative group which can be written as a product of two cycle proper-subgroup of order p.

With respect to conjugacy,the cyclic subgroups of order 6 contained in GL(4,Z) are discussed.

In this paper,the author describes the results of the number of subgroups in a group of order n,raises the guess that the lower bound of the number of subgroup is T(n),discusses the number of cyclic subgroup and the number of maximal subgroup in a commutative group of order n,studies structure of some groups.

We denote by n(G) the number of subgroups of minimum coverings by subgroups of G,and denote by n_c(G) the number of subgroups of minimum coverings by cyclic subgroups of G,and denote by n_a(G) the number of subgroups of minimum coverings by Abelian subgroups of G,then(1)3≤n(G)≤|G|-1,(2)n_c(C_p×…×C_p)m个=pm-1+…+p+1,where m≥2,(3)n_c(C_pr×C_p)=r(p-1)+2,where r≥1,(4)n_a(C_pr×C_ps)=p+1,where r≥s≥1.

This paper proves that the metacyclic groups of order qp are weak(q-1)-DCI groups but not q-DCI groups,where q and p are distinct prime numbers satisfing 2<q<p.