The IEEE 802.11b standard also defines the WEP authentication and encryption method to mitigate security concerns. Generally, authentication methods are utilized to protect against unauthorized access to the network, whereas encryption is used to defeat eavesdroppers who may try to decrypt captured transmissions. The 802.11 standard uses WEP for both encryption and authentication.

Four options are available when using WEP:

1. Do not use WEP.

2. Use WEP for encryption only.

3. Use WEP for authentication only.

4. Use WEP for authentication and encryption only.

WEP encryption is based on RC4, which uses a 40-bit key in conjunction with a 24-bit random initialization vector to encrypt wireless data transmissions. (This is why you may see some 802.11b systems labeled as having 64-bit encryption. They are no different than those labeled as having 40-bit encryption keys.) If enabled, the same WEP key must be used on all clients and access points for communication. Most vendors today also offer 128-bit WEP (which uses a 104-bit key), a stronger encryption method that increases difficulty for eavesdroppers to decipher over-the-air transmissions. While not part of the IEEE 802.11b standard, this mode has been implemented on many different vendors' products, some of which are not interoperable.

To prevent unauthorized access, WEP also defined an authentication protocol. Two forms of authentication are defined by 802.11b: opens system and shared key. Open system authentication allows any 802.11b client to associate with the access point and skip the authentication process. There is neither any authentication of clients nor encryption of data.