中文摘要：

K匿名技术是当前轨迹隐私保护的主流方法，但该方法也存在隐私泄露的风险。该文提出一种在移动社交网络中基于代理转发机制（BAFM）的轨迹隐私保护方法。该方法利用安全多方计算和内积安全计算进行隐私加密匹配，通过可信服务器在移动社交网络中找最匹配的用户做代理，然后由代理转发用户的请求到服务器进行查询，隐藏用户的真实轨迹与位置服务器的联系，有效保护用户的轨迹隐私。安全分析表明该方法能有效保护用户的轨迹隐私；同时，通过实验验证该方法相对K匿名更高效，能减小服务器的查询和通信开销。

英文摘要：

The trajectory K-anonymous is the mainstream of the current trajectory privacy protection, but the method has some defects such as privacy leakage. In this paper, a method of trajectory privacy preserving is proposed Based on Agent Forwarding Mechanism （BAFM） in mobile social networks, which uses secure multi-party computation and inner product secure computation to find the best matching user by the trusted server as the agent. The agent forwards the user＇s request to the server to query, which hides the correlation between user＇s real trajectory and the server in order to achieve user＇s trajectory privacy. Security analysis shows that the propose method can effectively protect the user＇s trajectory privacy. Experiments show that the proposed method is more effective, it reduces the overhead of server＇s query and communication.