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Prestige 2602HWNLI-D7A Support Notes
All contents copyright (c) 2007 ZyXEL Communications Corporation.
101
WEP configuration (Wired Equivalent Privacy)
Introduction
The 802.11 standard describes the communication that occurs in wireless LANs.
The Wired Equivalent Privacy (WEP) algorithm is used to protect wireless communication from
eavesdropping, because wireless transmissions are easier to intercept than transmissions over wired
networks, and wireless is a shared medium, everything that is transmitted or received over a wireless
network can be intercepted.
WEP relies on a secret key that is shared between a mobile station (e.g. a laptop with a wireless Ethernet
card) and an access point (i.e. a base station). The secret key is used to encrypt packets before they are
transmitted, and an integrity check is used to ensure that packages are not modified during the transition.
The standard does not discuss how the shared key is established. In practice, most installations use a
single key that is shared between all mobile stations and access points APs.
WEP employs the key encryption algorithm, Ron's Code 4 Pseudo Random Number Generator (RC4
PRNG). The same key is used to encrypt and decrypt the data.
WEP has defended against this attack. To avoid encrypting two cipher texts with the same key stream, an
Initialisation Vector (IV) is used to augment the shared WEP key (secret key) and produce a different
RC4 key for each packet, the IV is also included in the package. WEP key (secret key) are available in
two types, 64-bits and 128-bits. Many times you will see them referenced as 40-bits and 104-bits instead.
The reson for this misnomer is that the WEP key ( 40/104 bits ) is concatenated with the initialisation
vector ( 24 bits ) resulting in a 64/128 bit total key size.