Bedienungsanleitung ZyXEL NBG4615 v2 (Seite 288 von 308) (Englisch)

544174

288

Zoom out

Zoom in

Vorherige Seite

1/308

Nächste Seite

Appendix D Wireless LANs

NBG4615 v2 User’s Guide

288

Encryption

WPA improves data encryption by using Temporal Key Integrity Protocol (TKIP), Message Integrity

Check (MIC) and IEEE 802.1x. WPA2 also uses TKIP when required for compatibility reasons, but

offers stronger encryption than TKIP with Advanced Encryption Standard (AES) in the Counter

mode with Cipher block chaining Message authentication code Protocol (CCMP).

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 and WPA2 regularly change 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

clients. This all happens in the background automatically.

The Message Integrity Check (MIC) is designed to prevent an attacker from capturing data packets,

altering them and resending them. The MIC provides a strong mathematical function in which the

receiver and the transmitter each compute and then compare the MIC. If they do not match, it is

assumed that the data has been tampered with and the packet is dropped.

By generating unique data encryption keys for every data packet and by creating an integrity

checking mechanism (MIC), with TKIP and AES it is more difficult to decrypt data on a Wi-Fi

network than WEP and difficult for an intruder to break into the network.

The encryption mechanisms used for WPA(2) and WPA(2)-PSK are the same. The only difference

between the two is that WPA(2)-PSK uses a simple common password, instead of user-specific

credentials. The common-password approach makes WPA(2)-PSK susceptible to brute-force

password-guessing attacks but it’s still an improvement over WEP as it employs a consistent,

single, alphanumeric password to derive a PMK which is used to generate unique temporal

encryption keys. This prevent all wireless devices sharing the same encryption keys. (a weakness of

WEP)

User Authentication

WPA and WPA2 apply IEEE 802.1x and Extensible Authentication Protocol (EAP) to authenticate

wireless clients using an external RADIUS database. WPA2 reduces the number of key exchange

messages from six to four (CCMP 4-way handshake) and shortens the time required to connect to a

network. Other WPA2 authentication features that are different from WPA include key caching and

pre-authentication. These two features are optional and may not be supported in all wireless

devices.

Key caching allows a wireless client to store the PMK it derived through a successful authentication

with an AP. The wireless client uses the PMK when it tries to connect to the same AP and does not

need to go with the authentication process again.

Pre-authentication enables fast roaming by allowing the wireless client (already connecting to an

AP) to perform IEEE 802.1x authentication with another AP before connecting to it.

Missbrauch melden von Frage und/oder Antwort

Libble nimmt den Missbrauch seiner Dienste sehr ernst. Wir setzen uns dafür ein, derartige Missbrauchsfälle gemäß den Gesetzen Ihres Heimatlandes zu behandeln. Wenn Sie eine Meldung übermitteln, überprüfen wir Ihre Informationen und ergreifen entsprechende Maßnahmen. Wir melden uns nur dann wieder bei Ihnen, wenn wir weitere Einzelheiten wissen müssen oder weitere Informationen für Sie haben.

ZyXEL NBG4615 v2 Seite 288

Brauchen Sie Hilfe? Stellen Sie Ihre Frage.

Missbrauch melden von Frage und/oder Antwort

Art des Missbrauchs:

Forenregeln

Neu registrieren

Andere Handbücher von ZyXEL NBG4615 v2

Das Handbuch wird per E-Mail gesendet. Überprüfen Sie ihre E-Mail.

Ihre Frage wurde zu diesem Forum hinzugefügt

Info