symmetric key对称密钥symmetricadj.对称的；匀称的symmetric key cryptography单钥体制symmetric operating system对称操作系统symmetric multilinear form对称多重线性型symmetric relative entropy对称相对熵symmetric clustering model对称聚类模型symmetric continuous group对称连续群symmetric Boolean function对称布尔函数symmetric positive solution对称正解symmetric Dulling equations对称Duffing方程symmetric cipher algorithms对称密码算法