中文摘要：

针对保护隐私的集合成员判定协议和集合相等判定协议泄露信息的缺陷，提出基于符号OBDD的解决方案。将集合成员编码成二进制码，提取集合的特征函数；以连分数和Cantor编码为桥梁，将集合编码为自然数，构造该自然数的比较相等函数；利用OBDD表示这2类函数，结合基于OBDD的安全函数评估协议，提出解决保护私有信息的集合相等判定问题和集合成员判定问题的2个协议。所提出的协议克服了已有解决方案存在的安全问题，且有较好的执行效率。

英文摘要：

Because the existing set member decision protocol and set equality protocol leak the private information of the sets, the protocols based on ordered binary decision diagram are proposed. The characteristic function of a set is extracted by en- coding the set members into binary code. In addition, using continued fraction and Cantor coding as a bridge, the set is enco- ded into a natural number, and then an equal function of the natural number is constructed. OBDD is used to represent the two kinds of functions, combined with security function evaluation protocols based on the OBDD, set member decision prob- lem and set equality problem are solved. Compared with the existing protocols, the two new ones can solve the security is- sues, and they have good execution efficiency.