Wired equivalent privacy (WEP)  encryption in 802.11 is very weak and is susceptible to cracking. The cracking involves the process of finding how the RC4 key is generated by WEP which is by concatenating the 5 or the 13 byte key with the 3 byte IV value. Additionally, it involves finding that how RC4 processes that key in the initial permutation and finally how the permutation is used to generate the initial key stream. The attacker can see the IV value moreover the first byte in the keystream might directly be related to one of the key bytes. Hence, observing enough of these key bytes, the attacker can find the key