(What is the length of the Initialization Vector (IV) in WEP?

WEP (Wired Equivalent Privacy) uses the RC4 stream cipher and combines a per-packet Initialization Vector (IV) with a shared secret key to form the RC4 seed for that packet’s keystream. The IV in WEP is 24 bits long and is transmitted in the clear as part of the 802.11 frame so the receiver can reconstruct the same per-packet RC4 key stream. The short IV space (2²⁴ possible values) is a major design weakness: on a busy network, IVs repeat frequently, causing keystream reuse. Because RC4 is a stream cipher, keystream reuse enables attackers to derive relationships between plaintexts and recover keys with statistical attacks (notably the Fluhrer, Mantin, and Shamir (FMS) family of attacks and related improvements). WEP also uses a CRC-32 integrity check (ICV) that is not cryptographically strong and is vulnerable to modification attacks. The 24-bit IV length is therefore a key reason WEP is considered insecure and has been replaced by WPA/WPA2 mechanisms that use stronger key mixing, larger nonces/IVs, and robust integrity protection.