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What is the differences between WEP shared Key and WEP OpenSystem Authentication’s. how are these methods working. Can we use CR4 in WEP Open system.
and how XOR will work in WEP Open system. is there any diffrence in 80.11b frames wen we use these methods like ACK and backoff ..etc

WEP encryption was introduced in 1999 for both data privacy and authentication. WEP open system authentication is based on request and grant. It is essentially no authentication.

WEP shared key authentication is based on request, challenge, challenge response, grant/deny. Before long WEP shared key authentication was found to be flawed and worse than open system authentication because it exposed the WEP key used for both initial authentication and ongoing data privacy.

The fix was to simply not use WEP shared key authentication - ever again. After the 802.11i amendment in 2004 the standard includes an optional second stage of authentication. So now the order is

Discover service set (probes and beacons)
Join service set (internal synchronization)
Open system authentication with access point
Association with access point
EAP Authentication with access point and AAA server (RADIUS)
Communicate through access point to other devices

I hope this helps. You have some other questions in your post that you might want to ask again. Thanks. /criss

which one othe authentication methods uesd CR4 ,
shared key or opensystem or both and what is the effect of RC4 on WEP methods

The stream cipher RC4 is used for the WEP cipher suite.
The stream cipher RC4 is used for the TKIP cipher suite, also known as WPA.
The block cipher AES is used for the CCMP cipher suite, also known as WPA2.

Shared key authentication is based on WEP and RC4.
Open system authentication uses no encryption, so it is not based on any cipher.

The RC4 cipher has not been discredited. WEP and shared key authentication have been discredited and should be avoided at all costs (my opinion).

I hope this helps. Thanks. /criss