Motorola AP-51 Series, Product Reference Manual

Page: 31 / 724

Introduction 1-13
The same device, host computer or front-end processor, usually performs both encryption and
decryption. The transmit or receive direction determines whether the encryption or decryption
function is performed. The device takes plain text, encrypts or scrambles the text typically by
mathematically combining the key with the plain text as instructed by the algorithm, then transmits
the data over the network. At the receiving end, another device takes the encrypted text and decrypts,
or unscrambles, the text revealing the original message. An unauthorized user can know the
algorithm, but cannot interpret the encrypted data without the appropriate key. Only the sender and
receiver of the transmitted data know the key.
Wired Equivalent Privacy (WEP) is an encryption security protocol specified in the IEEE Wireless
Fidelity (Wi-Fi) standard, 802.11b and supported by the AP. WEP encryption is designed to provide a
WLAN with a level of security and privacy comparable to that of a wired LAN. The level of protection
provided by WEP encryption is determined by the encryption key length and algorithm. An encryption
key is a string of case sensitive characters used to encrypt and decrypt data packets transmitted
between a mobile unit (MU) and the access point. An access point and its associated wireless clients
must use the same encryption key (typically 1 through 4) to interoperate.
For detailed information on WEP, see Configuring WEP Encryption on page 6-16 .
1.2.8.4 KeyGuard Encryption
Use KeyGuard to shield the master encryption keys from being discovered through hacking. KeyGuard
negotiation takes place between the access point and MU upon association. The access point can
use KeyGuard with Motorola MUs. KeyGuard is only supported on Motorola MUs making it a
Motorola proprietary security mechanism.
For detailed information on KeyGuard configurations, see Configuring KeyGuard Encryption on page
6-18 .
1.2.8.5 Wi-Fi Protected Access (WPA) Using TKIP Encryption
Wi-Fi Protected Access (WPA) is a security standard for systems operating with a Wi-Fi wireless
connection. WEP’s lack of user authentication mechanisms is addressed by WPA. Compared to WEP,
WPA provides superior data encryption and user authentication.
WPA addresses the weaknesses of WEP by including:
• a per-packet key mixing function
• a message integrity check
• an extended initialization vector with sequencing rules
• a re-keying mechanism