These functions provide software encryption support
for 802.11 device drivers.
function initializes crypto support for the interface
and sets the initialization vector (IV) for WEP encryption to
a random number derived from a secure PRNG.
function frees data structures associated with crypto support
for the interface
function runs the appropriate WEP encryption algorithm over the 802.11
encapsulated frame held in the mbuf chain
for transmission or reception on the interface
argument specifies whether the frame is being received or transmitted.
A value of 0 indicates that the frame is being received and should
therefore be decrypted; a non-zero value indicates that the frame
is being transmitted
and should be encrypted.