Wired Equivalent Privacy

INTRODUCTION Wired Equivalent Privacy (WEP) is a security algorithm for IEEE wireless networks. Introduced as part of the original 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.clear-text

3 MAJOR PROBLEMS WITH WEP 1)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. 2) 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. 3) 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 is especially dangerous because it establishes a false sense of security that cause people to be more willing to send sensitive data over the network. You still need to use some other encryption method on to of WEP - even at best it gives the privacy of a standard ethernet LAN.

WEP WEAKNESS There have been problems with WEP due to many security issues. In the 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.

2. WEP has the same problem as all systems based upon shared keys: any secret held by more than one person soon becomes public knowledge. An example is an employee who leaves a company... the employee still knows the shared WEP key and could sit outside the company sniffing network traffic or even attacking the internal network. 3. The initialization vector that seeds the WEP algorithm is sent in the clear. 4. The WEP checksum is linear and predictable.

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.