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7
Command Line Interface
multicast-cipher
This command defines the cipher algorithm used for broadcasting and multicasting
when using Wi-Fi Protected Access (WPA) security.
Syntax
multicast-cipher <AES | TKIP | WEP>
• AES - Advanced Encryption Standard
• TKIP - Temporal Key Integrity Protocol
• WEP - Wired Equivalent Privacy
Default Setting
WEP
Command Mode
Interface Configuration (Wireless)
Command Usage
• WPA enables the access point to support different unicast encryption keys
for each client. However, the global encryption key for multicast and
broadcast traffic must be the same for all clients. This command sets the
encryption type that is supported by all clients.
• If any clients supported by the access point are not WPA enabled, the
multicast-cipher algorithm must be set to WEP.
• WEP is the first generation security protocol used to encrypt data crossing
the wireless medium using a fairly short key. Communicating devices must
use the same WEP key to encrypt and decrypt radio signals. WEP has
many security flaws, and is not recommended for transmitting highly
sensitive data.
• TKIP provides data encryption enhancements including per-packet key
hashing (i.e., changing the encryption key on each packet), a message
integrity check, an extended initialization vector with sequencing rules, and
a re-keying mechanism.
• TKIP defends against attacks on WEP in which the unencrypted
initialization vector in encrypted packets is used to calculate the WEP key.
TKIP changes the encryption key on each packet, and rotates not just the
unicast keys, but the broadcast keys as well. TKIP is a replacement for
WEP that removes the predictability that intruders relied on to determine the
WEP key.
• AES has been designated by the National Institute of Standards and
Technology as the successor to the Data Encryption Standard (DES)
encryption algorithm, and will be used by the U.S. government for
encrypting all sensitive, nonclassified information. Because of its strength,
and resistance to attack, AES is also being incorporated as part of the
802.11 standard.
7-80
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