スライド 5 / 47
ノート :
- Authentication to the Access Point
- The first portion of WEP security is the authentication process to the Access Point itself. This can be done in one of two manners: open or shared key. This is a decision that needs to be made when the overall encryption scheme is designed.
- With open key authentication the entire authentication process is done clear text. This means since the entire process is done unencrypted, a client can associate to the AP with the wrong WEP key or no WEP key. But as soon as the client tries to send or receive data it cannot due to not having the correct key to process the packet.
- With shared key there is a challenge text packet that is sent within the authentication process. If the client has the wrong key or no key it will fail this portion of the authentication process and not be allowed to associate to the AP.
- This choice (open or shared key) is manually set on each device (AP and client), in which they have to match or the association will fail. The default value is for open authentication. The following sections explain the entire association process. The association process can be broken down into three elements: probe, authentication and association.
- 2.1 Probe phase: When a client is initialized it first sends out a probe request packet out all the channels. The AP’s that hear this packet will then send a probe response packet back to the station. This probe response packet contains information, which the client utilizes to make an assessment of which AP to continue the association process with.
