Extreme Networks Summit WM Series Podręcznik Użytkownika Pobierz pdf (Strona 99)

Privacy for a WM-AD

Summit WM-Series WLAN Switch and Altitude Access Point Software Version 1.0 User Guide

The encryption portion of WPA v1 is Temporal Key Integrity Protocol (TKIP). TKIP includes:

● a per-packet key mixing function that shares a starting key between devices, and then changes their

encryption key for every packet or after the specified re-key time interval.

● a extended WEP key length of 256-bits

● an enhanced Initialization Vector (IV) of 48 bits, instead of 24 bits, making it more difficult to

compromise.

● a Message Integrity Check or Code (MIC), an additional 8-byte code that is inserted before the

standard WEP 4-byte Integrity Check Value (ICV). These integrity codes are used to calculate and

compare, between sender and receiver, the value of all bits in a message, to ensure that the message

has not been tampered with.

The encryption portion of WPA v2 is Advanced Encryption Standard (AES). AES includes:

● a 128 bit key length, for the WPA2/802.11i implementation of AES

● four stages that make up one round. Each round is iterated 10 times. a per-packet key mixing

function that shares a starting key between devices, and then changes their encryption key for every

packet or after the specified re-key time interval.

● the Counter-Mode/CBC-MAC Protocol (CCMP), a new mode of operation for a block cipher that

enables a single key to be used for both encryption and authentication. The two underlying modes

employed in CCM include

● Counter mode (CTR) that achieves data encryption

● Cipher Block Chaining Message Authentication Code (CBC-MAC) to provide data integrity

The steps in the WPA authentication and encryption process are as follows:

1 The wireless device client associates with Altitude AP.

2 Altitude AP blocks the client's network access while the authentication process is carried out (the

Summit WM-Series Switch sends the authentication request to the RADIUS authentication server).

3 The wireless client provides credentials that are forwarded by the Summit WM-Series Switch to the

authentication server.

4 If the wireless device client is not authenticated, the wireless client stays blocked from network

access.

5 If the wireless device client is authenticated, the Summit WM-Series Switch distributes encryption

keys to the Altitude AP and the wireless client.

6 The wireless device client gains network access via the Altitude AP, sending and receiving encrypted

data. The traffic is controlled with permissions and policy applied by the Summit WM-Series Switch.

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Extreme Networks Summit WM Series Podręcznik Użytkownika Strona 99