 the making the aforesaid attacks relatively easy to carry out. use of VPNs and SSL web security. The advantage of this Some of the problems noted above can be solved security approach is that protection against eavesdrop- completely within the existing standards. Weak IVs can ping at any stage of the communications process, not just be avoided proactively, and some vendors have already the wireless link, is obtained. However, VPNs are com- implemented filters that ensure that weak IVs are never plex to set up and maintain and may not support roaming used by their stations. If all stations on a network avoid of the wireless device from one access point to another, weak IVs, the FMS attack cannot be carried out. Weak particularly if the IP address of the mobile device un- hashing algorithms for short keys can be avoided by en- dergoes a change due to the roaming process. tering keys directly as hexadecimal numbers. In home networks with few users and relatively light traffic, manual key exchange on a weekly or even monthly basis 5.1.4 HiperLAN and HiperLAN 2 will most likely raise the effort involved in a successful attack above any gains that can be realized. Some of the researchers who participated in defining the The simple measures cited above can hardly be 802.1 standard were also active in similar European regarded as adequate for sensitive industrial or govern- efforts: the resulting standards are known as HiperLAN. mental data. In 2003, products conforming to a pre- The HiperLAN 2 physical layer is very similar to that liminary standard promulgated by the WECA industrial used in 802.11a: it is an OFDM system operating in the consortium, known as Wi-Fi Protected Access 5-GHz band, using an almost identical set of modulations (WPA), became available. WPA is a partially backward- and code rates to support nearly the same set of data compatible enhancement of WEP. WPA uses the IEEE rates. The physical layer is also compliant with ETSI 802. 1x standard as a framework for authentication of requirements for dynam