r to that used in public key infrastructures (PKI). Only those devices with a valid shared key can be associated with an Privacy: By default, data is transferred "in the clear;" any 802.11- compliant device can potentially eavesdrop, such as PHY 802.11 traffic that is within range. WEP encrypts the data before it is Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Access Technologies Chapter 6 transmitted, using a 40-bit encryption algorithm known as RC4. The same shared key used in authentication is used to encrypt or decrypt the data; only clients with the correct shared key can decipher the data. Power management: 802.11 defines an active mode, in which a wireless client is powered at a level adequate to transmit and receive, and a power save mode, under which a client is not able to transmit or receive, but consumes less power while in a "standby mode" of sorts. 802.11 has garnered a great deal of attention in recent months, par- ticularly with the perceived competition from Bluetooth, another short- distance wireless protocol. Significantly more activity is underway in the 802.11 space, however, with daily product announcements throughout the industry. Various subcommittees have been created that address everything from security to voice transport to quality-of-service; it is a technology to watch. Wi-Fi in Action Wi-Fi is a remarkably simple technology. In fact, most new laptops come equipped with a built-in Wi-Fi card. The card, which is simply a radio, serves to connect the computer or PDA in which it is installed to a base station known as a hotspot. The hotspot is simply the central point of connection for a computer to the network; typically it is a small device that is connected to the Internet, often via a DSL facility, as shown in Figure 6-18. The hotspot typically contains an 802.11-based radio that has the ability to engage in