A new trace function was proposed,the XTP public key cryptosystem based on the 3-rd order LFSR se-quence(the so-called XTR3 system) was extended to the XTR4 system based on the 4-th order LFSR sequence.

• 提出一种新的迹函数,将基于3阶LFSR序列的XTR公钥密码体制(称之为XTR3体制),改进为基于4阶LFSR序列的XTR4公钥密码体制。