User’s Manual for the NETGEAR Double 108 Mbps Wireless PC Card 32-bit CardBus WG511U
2.The access point sends challenge text to the station.
3.The station uses its configured 64-bit or 128-bit default key to encrypt the challenge text, and sends the encrypted text to the access point.
4.The access point decrypts the encrypted text using its configured WEP Key that corresponds to the station’s default key. The access point compares the decrypted text with the original challenge text. If the decrypted text matches the original challenge text, then the access point and the station share the same WEP Key and the access point authenticates the station.
5.The station connects to the network.
If the decrypted text does not match the original challenge text (i.e., the access point and station do not share the same WEP Key), then the access point will refuse to authenticate the station and the station will be unable to communicate with either the 802.11 network or Ethernet network.
WEP Keys
The IEEE 802.11 standard supports two types of WEP encryption: 64-bit and 128-bit. 128-bit encryption is stronger than 64-bit encryption, but 128-bit encryption may not be available outside of the United States due to U.S. export regulations.
•64-bit WEP
The 64-bit WEP data encryption method, allows for a five-character (40-bit) input. Additionally, 24 factory-set bits are added to the forty-bit input to generate a 64-bit encryption key. (The 24 factory-set bits are not user-configurable). This encryption key will be used to encrypt/decrypt all data transmitted via the wireless interface. Some vendors refer to the 64-bit WEP data encryption as 40-bit WEP data encryption since the user-configurable portion of the encryption key is 40 bits wide.
When configured for 64-bit encryption, 802.11 products typically support up to four WEP Keys. Each 64-bit WEP Key is expressed as 5 sets of two hexadecimal digits (0-9 and A-F). For example, “12 34 56 78 90” is a 40-bit WEP Key.
•128-bit WEP
The 128-bit WEP data encryption method consists of 104 user-configurable bits. Similar to the forty-bit WEP data encryption method, the remaining 24 bits are factory set and not user configurable. Some vendors allow passphrases to be entered instead of the cryptic hexadecimal characters to ease encryption key entry.
Wireless Networking Basics | B-9 |
