Applications and the Future - Codes: The Guide to Secrecy from Ancient to Modern Times - page 351

Diagram 9.5 TKIP Encapsulation

TK
−−−−→
TA
−−−−→
SEQ
−−−−→

Per-Packet
Key
Mixing
Function

PPK
−−−−−−−−−−−→

W
E
P

Plaintext
−−−−−−−−→
MPDU

SEQ
−−−−→

Fragment E

N
C
R
Y
P
T
I
O
N

↑
Plaintext MSDU
and MIC
↑

Ciphertext
−−−−−−−−−−→
MPDU

MK
−−−−→
SA
−−−−→
DA
−−−−→
Plaintext
−−−−−−−−→
MSDU

M
I
C
H
A
E
L

Conclusions
TGI's ratification of 802.11i takes the above-described WPA a giant stride
forward, and is now often called WPA2 . Since RSN uses AES, encryption
strength is vastly increased. However, some existing hardware cannot simply be
upgraded as was possible with the transition to WPA. In other words, some of
the older hardware simply has to be replaced, as we mentioned in the context
of the RSN summary in part 1 on page 345. However, now that ratification of
802.11i is a fact, we will see the distribution of AES-compliant equipment.
WPA2 advances in another important fashion since it enciphers the entire
data frame, whereas WPA encrypts only the payload. That said, coordinating
the inter- and backward-compatibility of the system at large is clearly still a
challenge to be met. Thus, although the TGi is now disbanded, there is still
work to be done. For instance, we await the resolution of the standard from
TGn. There also exists the TGr group that works on 802.11r, for fast hand-off in
those situations where a wireless client is moving, on the same WLAN, from one
AP to another. Another is the TGs roup workingon codifyingrequirements
for standardization of self-configuring mesh networks.