When you use your client adapter with the Mac OS operating system, you can protect your data as it is transmitted through your wireless network by encrypting it through the use of Wired Equivalent Privacy (WEP) encryption keys. With WEP encryption, the transmitting device encrypts each packet with a WEP key, and the receiving device uses that same key to decrypt each packet.

The WEP keys used to encrypt and decrypt transmitted data can be statically associated with your adapter or dynamically created as part of the LEAP authentication process. The information in the sections below can help you to decide which type of WEP keys you want to use. Dynamic WEP keys with LEAP offer a higher degree of security than static WEP keys.

WEP keys, whether static or dynamic, are either 40 or 128 bits in length. The 128-bit WEP keys contain more characters than the 40-bit keys and, therefore, offer a greater level of security. Message integrity check (MIC) is a security protection feature supported by your client adapter in conjunction with an access point (see the “MIC” section on page 5-4).

Each device (or profile) within your wireless network can be assigned up to four static WEP keys. If a device receives a packet that is not encrypted with the appropriate key (as the WEP keys must match in all devices that are to communicate with each other), the device discards the packet.

For the Mac OS X, the Static WEP keys are stored in an encrypted format (for security reasons) in your Macintosh. When the driver loads and reads the client adapter’s parameters, it also finds the static WEP keys, decrypts them, and stores them in volatile memory on the client adapter. The WEP keys in the client adapter are temporary and they are lost when power to the adapter is removed or the Macintosh is rebooted. Although the keys in the client adapter are temporary, you do not need to re-enter them when you restore power or reboot because the keys are stored in your Macintosh. For the Mac OS 9, the Static WEP keys can be permanently or temporarily stored in your client adapter. If the keys are temporarily stored in volatile memory, the keys will be lost when power is removed from your client adapter.

Download pdf Cisco Aironet Wireless LAN Client Adapters Installation and Configuration Guide for Mac OS