tailieunhanh - Enabling Technologies for Wireless E-Business phần 3

Phần này nói về hệ thống thông tin liên lạc được sử dụng hầu hết các mạng GSM và hệ thống 3G hiện tại phổ biến nhất. Có nhiều tiêu chuẩn cho các hệ thống 3G, nhưng chúng tôi chọn hệ thống phổ Viễn thông Điện thoại di động (UMTS) cho khả năng tương thích với GSM, tốt hơn chứng minh cơ chế bảo mật máy chủ hỗ trợ hoạt động như thế nào. | 3 Wireless Security 69 WWAN Security Infrastructure This section talks about the most used GSM communication system and the current most popular 3G systems. There are many standards for the 3G systems but we pick Universal Mobile Telecommunications System UMTS for its compatibility with GSM to better demonstrate how the server assisted security mechanism operates. The Security Architecture WWAN covers a very broad service area in a hierarchical structure consisting of many Visited Location Registers VLRs . With such vast amount of VLRs their computation and storage ability are naturally limited by cost causing it infeasible to store all the subscriber data and a more powerful centralized server is called for which is HLR AuC Home Location Register Authentication Center . Fig. shows the GSM communication infrastructure and in general the AuC would be attached to a HLR in a secure environment. The Authentication Center AuC securely stores the secret keys of all subscribers for later user authentication purposes. Other personal information not involved with authentication is stored on the HLR. Besides it is assume that there is a secure channel between HLR AuC and the visited network for delivering sensitive information such as user authentication information for assisting visited network providers in authenticating the user. The VLR which is the visited network providers authenticates the user based on the information obtained from HLR AuC. It is no doubt that HLR AuC is the key to successfully authenticate both the MS and the VLR. The authenticating capability of the HLR AuC comes from the key shared with MS. Based on the knowledge of this key the corresponding authenticator can be derived to convince to the VLR that the MS is the alleged one. This way the user is approved to access the resources within visited network without obstacle. Fig. . GSM communication infrastructure GSM Authentication Fig. illustrates the GSM authentication process. The