WEP Key size in bits - 40 or 104. Note that if you are planning to use Kerberos as the authentication mechanism, you cannot choose the WEP key size as 40 bits, because Kerberos authentication results in 104 bit keys. Also note that TKIP cannot be used along with 40 bit WEP encryption. If TKIP has to be used along with WEP, the WEP key size must be 104 bits. Further, if Keyguard has to be used along with WEP, then also the WEP key size must be 104 bits.