无线漫游安全 (Secure Wireless Roaming, SWR) 协议允许隶属于本地服务器的用户漫游到外地时，可以与外地服务器互相验证身份并建立安全的会话密钥。在此基础上，匿名 SWR 协议能保证即使所有外地服务器串通情况下漫游用户的匿名性和不可追踪性。该文提出了一个匿名的无线漫游安全协议 SYM-SWR (SYMmetric key based SWR)。而且就目前所知，该协议是第 1 个完全基于对称密钥的匿名 SWR。同其他已知协议相比，SYM-SW 的通信复杂度和计算复杂度均最低。因为 SYM-SWR 只需要 4 次消息传送，且不需要 PKI (Public Key Infrastructure) 而采用消息验证码 (Message Authentication Code, MAC) 和对称密钥加密这两种高效的运算。

Secure Wireless Roaming (SWR) allows a roaming user under the subscription of its home server to establish a secure session key with a foreign server in an authenticated way such that both the foreign server and the roaming user can mutually authenticate each other. Anonymous SWR provides an additional service to the roaming user so that the roaming user can keep anonymous and untraceable even if all the visited foreign servers are colluding with each other. In this paper, an anonymous SWR called SYM-SWR (SYMmetric key based SWR) is proposed. To best of our knowledge, it seems to be the first pure symmetric key based anonymous SWR. Compared with other existing SWR protocols both of the computation complexity and communication complexity of SYM-SWR are lowest, since it involves only 4 message flows and no PKI (Public Key Infrastructure) but only highly efficient cryptographic operations are needed which include Message Authentication Code (MAC) and symmetric key encryption.