14-08-2013, 03:05 PM
Wired Equivalent Privacy
Wired Equivalent.pptx (Size: 113.84 KB / Downloads: 25)
INTRODUCTION
Wired Equivalent Privacy (WEP) is a security algorithm for IEEE 802.11 wireless networks. Introduced as part of the original 802.11 standard ratified in September 1999, its intention was to provide data confidentiality comparable to that of a traditional wired network. WEP, recognizable by the key of 10 or 26 hexadecimal digits, is widely in use and is often the first security choice presented to users by router configuration tools.
AUTHENTICATION
Two methods of authentication can be used with WEP: Open System authentication and Shared Key authentication.
OPEN SYSTEM AUTHENTICATION
In Open System authentication, the WLAN client need not provide its credentials to the Access Point during authentication. Any client can authenticate with the Access Point and then attempt to associate. In effect, no authentication occurs. Subsequently WEP keys can be used for encrypting data frames. At this point, the client must have the correct keys.
SHARED KEY AUTHENTICATION
In Shared Key authentication, the WEP key is used for authentication in a four step challenge-response handshake:
The client sends an authentication request to the Access Point.
The Access Point replies with a clear-text challenge.
The client encrypts the challenge-text using the configured WEP key, and sends it back in another authentication request.
The Access Point decrypts the response. If this matches the challenge-text the Access Point sends back a positive reply.
3 MAJOR PROBLEMS WITH WEP
Key distribution. If you aren't the only person on the network, getting the key out to other people is a non-trivial task and can be the weakest link.
40-bit - the standard WEP keysize is completely insufficient and can be cracked in relatively no time. 128bit versions of the hardware are available, however, so this is an improvement.
This is the biggie - the WEP authentication protocol relies on DNS and is therefore prone to massive man-in-the-middle attacks. There is a paper by Jesse Walker called "Wireless LANs Unsafe at Any Key Size; and analysis of the WEP encapsulation" that I encourage everyone to read.
WEP WEAKNESS
There have been problems with WEP due to many security issues. In the 802.11 standard, WEP is defined as "protecting authorized users of a WLAN from casual eavesdropping." As such, WEP is not a terribly strong form of protection and is subject to numerous exploits based on vulnerabilities and weaknesses.
These include:
1. A high percentage of wireless networks have WEP disabled because of the administrative overhead of maintaining a shared WEP key.
CONCLUSION
Wired Equivalent Privacy (WEP) isn't. The protocol's problems are a result of misunderstanding of some cryptographic primitives and therefore combining them in insecure ways. These attacks point to the importance of inviting public review from people with expertise in cryptographic protocol design; had this been done, the problems stated here would have surely been avoided.