Wired Equivalent Privacy (WEP)
WEP is a short hand description for Wired Equivalent Privacy; WEP is a wireless local area network (WLAN) security protocol, which is defined in 802.11b standard. As such WEP is able to provide the same level security as those found in the normal wired LAN networks. However, it is obvious that WEP could be susceptible to attacks not present in physically located networks which can be protected with a physical structure such as a building or think cabling. WLAN protocols are transmitted over radio waves and could be subject to interception and tampering and as such WEP is aimed to provide encryption of transmissions to help prevent this.
WEP is part of the IEEE 802.11 standard ratified in September 1999. WEP uses the stream cipher RC4 for confidentiality and the CRC-32 checksum for integrity.
Standard 64-bit WEP uses a 40 bit key, which is concatenated to a 24-bit initialization vector (IV) to form the RC4 traffic key. At the time that the original WEP standard was being drafted, US Government export restrictions on cryptographic technology limited the keysize. Once the restrictions were lifted, all of the major manufacturers eventually implemented an extended 128-bit WEP protocol using a 104-bit key size. A 128-bit WEP key is almost always entered by users as a string of 26 Hexadecimal (Hex) characters (0-9 and A-F). Each character represents 4 bits of the key. 4 * 26 = 104 bits. Adding the 24-bit IV brings us what we call a "128-bit WEP key". A 256-bit WEP system is available from some vendors, and as with the above-mentioned system, 24 bits of that is for the I.V., leaving 232 actual bits for protection. This is typically entered as 58 Hexadecimal characters. (58 * 4 = 232 bits) + 24 I.V. bits = 256 bits of WEP protection.
Key size is not the major security limitation in WEP. Cracking a longer key requires interception of more packets, but there are active attacks that stimulate the necessary traffic. There are other weaknesses in WEP, including the possibility of IV collisions and altered packets, that are not helped at all by a longer key.
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