ZyXEL Communications NBG-415N, User Manual

Page: 136 / 155

ZyXEL NBG-415N User’s Guide
Appendix B Wireless LANs 136
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(2)
Wi-Fi Protected Access (WPA) is a subset of the IEEE 802.11i standard. WPA2 (IEEE
802.11i) is a wireless security standard that defines stronger encryption, authentication and
key management than WPA.
Key differences between WPA(2) and WEP are improved data encryption and user
authentication.
Encryption
Both WPA and WPA2 improve data encryption by using Temporal Key Integrity Protocol
(TKIP), Message Integrity Check (MIC) and IEEE 802.1x. In addition to TKIP, WPA2 also
uses Advanced Encryption Standard (AES) in the Counter mode with Cipher block chaining
Message authentication code Protocol (CCMP) to offer stronger encryption.
Temporal Key Integrity Protocol (TKIP) uses 128-bit keys that are dynamically generated and
distributed by the authentication server. It includes 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.
TKIP regularly changes and rotates 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 pair-wise key to
dynamically generate unique data encryption keys to encrypt every data packet that is
wirelessly communicated between the AP and the wireless clients. This all happens in the
background automatically.
WPA2 AES (Advanced Encryption Standard) is a block cipher that uses a 256-bit
mathematical algorithm called Rijndael.
Table 61 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