ZyXEL M-302 Manual Do Utilizador

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M-302 User’s Guide
Appendix C
75
For added security, certificate-based authentications (EAP-TLS, EAP-TTLS and PEAP) use 
dynamic keys for data encryption. They are often deployed in corporate environments, but for 
public deployment, a simple user name and password pair is more practical. The following 
table is a comparison of the features of authentication types.
WPA
Wi-Fi Protected Access (WPA) is a subset of the IEEE 802.11i standard.
Key differences between WPA and WEP are improved data encryption and user 
authentication.
Select WEP only when the AP and/or wireless clients do not support WPA. WEP is less secure 
than WPA.
Encryption 
WPA improves data encryption by using Temporal Key Integrity Protocol (TKIP), Message 
Integrity Check (MIC) and IEEE 802.1x. WPA uses Advanced Encryption Standard (AES) in 
the Counter mode with Cipher block chaining Message authentication code Protocol (CCMP) 
to offer stronger encryption than TKIP.
TKIP uses 128-bit keys that are dynamically generated and distributed by the authentication 
server. AES (Advanced Encryption Standard) is a block cipher that uses a 256-bit 
mathematical algorithm called Rijndael. They both include a per-packet key mixing function, 
a Message Integrity Check (MIC) named Michael, an extended initialization vector (IV) with 
sequencing rules, and a re-keying mechanism.
WPA regularly changes and rotate the encryption keys so that the same encryption key is never 
used twice. 
The RADIUS server distributes a Pairwise Master Key (PMK) key to the AP that then sets up 
a key hierarchy and management system, using the PMK to dynamically generate unique data 
encryption keys to encrypt every data packet that is wirelessly communicated between the AP 
and the wireless stations. This all happens in the background automatically.
Table 29   Comparison of EAP Authentication Types
EAP-MD5
EAP-TLS
EAP-TTLS
PEAP
LEAP
Mutual Authentication
No
Yes
Yes
Yes
Yes
Certificate – Client
No
Yes
Optional
Optional
No
Certificate – Server
No
Yes
Yes
Yes
No
Dynamic Key Exchange
No
Yes
Yes
Yes
Yes
Credential Integrity
None
Strong
Strong
Strong
Moderate
Deployment Difficulty
Easy
Hard
Moderate
Moderate
Moderate
Client Identity Protection
No
No
Yes
Yes
No