<s>
Wired	B-Protocol
Equivalent	I-Protocol
Privacy	I-Protocol
(	O
WEP	O
)	O
was	O
a	O
security	B-Application
algorithm	O
for	O
802.11	O
wireless	O
networks	O
.	O
</s>
<s>
Introduced	O
as	O
part	O
of	O
the	O
original	O
IEEE	O
802.11	O
standard	O
ratified	O
in	O
1997	O
,	O
its	O
intention	O
was	O
to	O
provide	O
data	O
confidentiality	O
comparable	O
to	O
that	O
of	O
a	O
traditional	O
wired	O
network	B-Architecture
.	O
</s>
<s>
WEP	O
,	O
recognizable	O
by	O
its	O
key	O
of	O
10	O
or	O
26	O
hexadecimal	O
digits	O
(	O
40	O
or	O
104	O
bits	O
)	O
,	O
was	O
at	O
one	O
time	O
widely	O
used	O
,	O
and	O
was	O
often	O
the	O
first	O
security	B-Application
choice	O
presented	O
to	O
users	O
by	O
router	O
configuration	O
tools	O
.	O
</s>
<s>
WPA2	O
)	O
,	O
the	O
IEEE	O
declared	O
that	O
both	O
WEP-40	B-Protocol
and	O
WEP-104	B-Protocol
have	O
been	O
deprecated	O
.	O
</s>
<s>
However	O
,	O
some	O
802.11b	O
devices	O
were	O
later	O
provided	O
with	O
firmware	B-Application
or	O
software	O
updates	O
to	O
enable	O
WPA	O
,	O
and	O
newer	O
devices	O
had	O
it	O
built	O
in	O
.	O
</s>
<s>
WEP	O
was	O
ratified	O
as	O
a	O
Wi-Fi	B-Application
security	I-Application
standard	O
in	O
1999	O
.	O
</s>
<s>
WEP	O
uses	O
the	O
stream	B-Algorithm
cipher	I-Algorithm
RC4	B-Algorithm
for	O
confidentiality	O
,	O
and	O
the	O
CRC-32	O
checksum	O
for	O
integrity	O
.	O
</s>
<s>
Standard	O
64-bit	O
WEP	O
uses	O
a	O
40-bit	O
key	O
(	O
also	O
known	O
as	O
WEP-40	B-Protocol
)	O
,	O
which	O
is	O
concatenated	O
with	O
a	O
24-bit	O
initialization	B-Algorithm
vector	I-Algorithm
(	O
IV	O
)	O
to	O
form	O
the	O
RC4	B-Algorithm
key	O
.	O
</s>
<s>
Once	O
the	O
restrictions	O
were	O
lifted	O
,	O
manufacturers	O
of	O
access	O
points	O
implemented	O
an	O
extended	O
128-bit	O
WEP	O
protocol	O
using	O
a	O
104-bit	O
key	O
size	O
(	O
WEP-104	B-Protocol
)	O
.	O
</s>
<s>
A	O
64-bit	O
WEP	B-Protocol
key	I-Protocol
is	O
usually	O
entered	O
as	O
a	O
string	O
of	O
10	O
hexadecimal	O
(	O
base	O
16	O
)	O
characters	O
(	O
0	O
–	O
9	O
and	O
A	O
–	O
F	O
)	O
.	O
</s>
<s>
Each	O
character	O
represents	O
4	O
bits	O
,	O
10	O
digits	O
of	O
4	O
bits	O
each	O
gives	O
40	O
bits	O
;	O
adding	O
the	O
24-bit	O
IV	O
produces	O
the	O
complete	O
64-bit	O
WEP	B-Protocol
key	I-Protocol
(	O
4	O
bits	O
×	O
10	O
+	O
24-bit	O
IV	O
=	O
64-bit	O
WEP	B-Protocol
key	I-Protocol
)	O
.	O
</s>
<s>
Most	O
devices	O
also	O
allow	O
the	O
user	O
to	O
enter	O
the	O
key	O
as	O
5	O
ASCII	B-Protocol
characters	I-Protocol
(	O
0	O
–	O
9	O
,	O
a	O
–	O
z	O
,	O
A	O
–	O
Z	O
)	O
,	O
each	O
of	O
which	O
is	O
turned	O
into	O
8	O
bits	O
using	O
the	O
character	O
's	O
byte	O
value	O
in	O
ASCII	B-Protocol
(	O
8	O
bits	O
×	O
5	O
+	O
24-bit	O
IV	O
=	O
64-bit	O
WEP	B-Protocol
key	I-Protocol
)	O
;	O
however	O
,	O
this	O
restricts	O
each	O
byte	O
to	O
be	O
a	O
printable	O
ASCII	B-Protocol
character	I-Protocol
,	O
which	O
is	O
only	O
a	O
small	O
fraction	O
of	O
possible	O
byte	O
values	O
,	O
greatly	O
reducing	O
the	O
space	O
of	O
possible	O
keys	O
.	O
</s>
<s>
A	O
128-bit	O
WEP	B-Protocol
key	I-Protocol
is	O
usually	O
entered	O
as	O
a	O
string	O
of	O
26	O
hexadecimal	O
characters	O
.	O
</s>
<s>
26	O
digits	O
of	O
4	O
bits	O
each	O
gives	O
104	O
bits	O
;	O
adding	O
the	O
24-bit	O
IV	O
produces	O
the	O
complete	O
128-bit	O
WEP	B-Protocol
key	I-Protocol
(	O
4	O
bits	O
×	O
26	O
+	O
24-bit	O
IV	O
=	O
128-bit	O
WEP	B-Protocol
key	I-Protocol
)	O
.	O
</s>
<s>
Most	O
devices	O
also	O
allow	O
the	O
user	O
to	O
enter	O
it	O
as	O
13	O
ASCII	B-Protocol
characters	I-Protocol
(	O
8	O
bits	O
×	O
13	O
+	O
24-bit	O
IV	O
=	O
128-bit	O
WEP	B-Protocol
key	I-Protocol
)	O
.	O
</s>
<s>
These	O
128	O
or	O
232	O
bits	O
are	O
typically	O
entered	O
as	O
32	O
or	O
58	O
hexadecimal	O
characters	O
(	O
4	O
bits	O
×	O
32	O
+	O
24-bit	O
IV	O
=	O
152-bit	O
WEP	B-Protocol
key	I-Protocol
,	O
4	O
bits	O
×	O
58	O
+	O
24-bit	O
IV	O
=	O
256-bit	O
WEP	B-Protocol
key	I-Protocol
)	O
.	O
</s>
<s>
Most	O
devices	O
also	O
allow	O
the	O
user	O
to	O
enter	O
it	O
as	O
16	O
or	O
29	O
ASCII	B-Protocol
characters	I-Protocol
(	O
8	O
bits	O
×	O
16	O
+	O
24-bit	O
IV	O
=	O
152-bit	O
WEP	B-Protocol
key	I-Protocol
,	O
8	O
bits	O
×	O
29	O
+	O
24-bit	O
IV	O
=	O
256-bit	O
WEP	B-Protocol
key	I-Protocol
)	O
.	O
</s>
<s>
Two	O
methods	O
of	O
authentication	O
can	O
be	O
used	O
with	O
WEP	O
:	O
Open	O
System	O
authentication	O
and	O
Shared	B-Algorithm
Key	I-Algorithm
authentication	O
.	O
</s>
<s>
In	O
Open	O
System	O
authentication	O
,	O
the	O
WLAN	O
client	O
does	O
not	O
provide	O
its	O
credentials	O
to	O
the	O
access	B-Device
point	I-Device
during	O
authentication	O
.	O
</s>
<s>
Any	O
client	O
can	O
authenticate	O
with	O
the	O
access	B-Device
point	I-Device
and	O
then	O
attempt	O
to	O
associate	O
.	O
</s>
<s>
Subsequently	O
,	O
WEP	B-Protocol
keys	I-Protocol
can	O
be	O
used	O
for	O
encrypting	O
data	O
frames	O
.	O
</s>
<s>
In	O
Shared	B-Algorithm
Key	I-Algorithm
authentication	O
,	O
the	O
WEP	B-Protocol
key	I-Protocol
is	O
used	O
for	O
authentication	O
in	O
a	O
four-step	O
challenge	O
–	O
response	O
handshake	O
:	O
</s>
<s>
The	O
client	O
sends	O
an	O
authentication	O
request	O
to	O
the	O
access	B-Device
point	I-Device
.	O
</s>
<s>
The	O
access	B-Device
point	I-Device
replies	O
with	O
a	O
clear-text	O
challenge	O
.	O
</s>
<s>
The	O
client	O
encrypts	O
the	O
challenge-text	O
using	O
the	O
configured	O
WEP	B-Protocol
key	I-Protocol
and	O
sends	O
it	O
back	O
in	O
another	O
authentication	O
request	O
.	O
</s>
<s>
The	O
access	B-Device
point	I-Device
decrypts	O
the	O
response	O
.	O
</s>
<s>
If	O
this	O
matches	O
the	O
challenge	O
text	O
,	O
the	O
access	B-Device
point	I-Device
sends	O
back	O
a	O
positive	O
reply	O
.	O
</s>
<s>
After	O
the	O
authentication	O
and	O
association	O
,	O
the	O
pre-shared	O
WEP	B-Protocol
key	I-Protocol
is	O
also	O
used	O
for	O
encrypting	O
the	O
data	O
frames	O
using	O
RC4	B-Algorithm
.	O
</s>
<s>
At	O
first	O
glance	O
,	O
it	O
might	O
seem	O
as	O
though	O
Shared	B-Algorithm
Key	I-Algorithm
authentication	O
is	O
more	O
secure	O
than	O
Open	O
System	O
authentication	O
since	O
the	O
latter	O
offers	O
no	O
real	O
authentication	O
.	O
</s>
<s>
It	O
is	O
possible	O
to	O
derive	O
the	O
keystream	O
used	O
for	O
the	O
handshake	O
by	O
capturing	O
the	O
challenge	O
frames	O
in	O
Shared	B-Algorithm
Key	I-Algorithm
authentication	O
.	O
</s>
<s>
Therefore	O
,	O
data	O
can	O
be	O
more	O
easily	O
intercepted	O
and	O
decrypted	O
with	O
Shared	B-Algorithm
Key	I-Algorithm
authentication	O
than	O
with	O
Open	O
System	O
authentication	O
.	O
</s>
<s>
If	O
privacy	O
is	O
a	O
primary	O
concern	O
,	O
it	O
is	O
more	O
advisable	O
to	O
use	O
Open	O
System	O
authentication	O
for	O
WEP	O
authentication	O
,	O
rather	O
than	O
Shared	B-Algorithm
Key	I-Algorithm
authentication	O
;	O
however	O
,	O
this	O
also	O
means	O
that	O
any	O
WLAN	O
client	O
can	O
connect	O
to	O
the	O
AP	O
.	O
</s>
<s>
(	O
Both	O
authentication	O
mechanisms	O
are	O
weak	O
;	O
Shared	B-Algorithm
Key	I-Algorithm
WEP	O
is	O
deprecated	O
in	O
favor	O
of	O
WPA/WPA2	O
.	O
)	O
</s>
<s>
Because	O
RC4	B-Algorithm
is	O
a	O
stream	B-Algorithm
cipher	I-Algorithm
,	O
the	O
same	O
traffic	O
key	O
must	O
never	O
be	O
used	O
twice	O
.	O
</s>
<s>
The	O
purpose	O
of	O
an	O
IV	O
,	O
which	O
is	O
transmitted	O
as	O
plaintext	O
,	O
is	O
to	O
prevent	O
any	O
repetition	O
,	O
but	O
a	O
24-bit	O
IV	O
is	O
not	O
long	O
enough	O
to	O
ensure	O
this	O
on	O
a	O
busy	O
network	B-Architecture
.	O
</s>
<s>
In	O
August	O
2001	O
,	O
Scott	O
Fluhrer	O
,	O
Itsik	O
Mantin	O
,	O
and	O
Adi	O
Shamir	O
published	O
a	O
cryptanalysis	O
of	O
WEP	O
that	O
exploits	O
the	O
way	O
the	O
RC4	B-Algorithm
ciphers	I-Algorithm
and	O
IV	O
are	O
used	O
in	O
WEP	O
,	O
resulting	O
in	O
a	O
passive	O
attack	O
that	O
can	O
recover	O
the	O
RC4	B-Algorithm
key	O
after	O
eavesdropping	O
on	O
the	O
network	B-Architecture
.	O
</s>
<s>
Depending	O
on	O
the	O
amount	O
of	O
network	B-Architecture
traffic	O
,	O
and	O
thus	O
the	O
number	O
of	O
packets	O
available	O
for	O
inspection	O
,	O
a	O
successful	O
key	O
recovery	O
could	O
take	O
as	O
little	O
as	O
one	O
minute	O
.	O
</s>
<s>
If	O
an	O
insufficient	O
number	O
of	O
packets	O
are	O
being	O
sent	O
,	O
there	O
are	O
ways	O
for	O
an	O
attacker	O
to	O
send	O
packets	O
on	O
the	O
network	B-Architecture
and	O
thereby	O
stimulate	O
reply	O
packets	O
,	O
which	O
can	O
then	O
be	O
inspected	O
to	O
find	O
the	O
key	O
.	O
</s>
<s>
It	O
is	O
possible	O
to	O
perform	O
the	O
attack	O
with	O
a	O
personal	O
computer	O
,	O
off-the-shelf	O
hardware	O
,	O
and	O
freely	O
available	O
software	O
such	O
as	O
aircrack-ng	B-Protocol
to	O
crack	O
any	O
WEP	B-Protocol
key	I-Protocol
in	O
minutes	O
.	O
</s>
<s>
by	O
default	O
,	O
WEP	O
relies	O
on	O
a	O
single	O
shared	B-Algorithm
key	I-Algorithm
among	O
users	O
,	O
which	O
leads	O
to	O
practical	O
problems	O
in	O
handling	O
compromises	O
,	O
which	O
often	O
leads	O
to	O
ignoring	O
compromises	O
.	O
</s>
<s>
In	O
2005	O
,	O
a	O
group	O
from	O
the	O
U.S.	O
Federal	O
Bureau	O
of	O
Investigation	O
gave	O
a	O
demonstration	O
where	O
they	O
cracked	O
a	O
WEP-protected	O
network	B-Architecture
in	O
three	O
minutes	O
using	O
publicly	O
available	O
tools	O
.	O
</s>
<s>
Andreas	O
Klein	O
presented	O
another	O
analysis	O
of	O
the	O
RC4	B-Algorithm
stream	B-Algorithm
cipher	I-Algorithm
.	O
</s>
<s>
Klein	O
showed	O
that	O
there	O
are	O
more	O
correlations	O
between	O
the	O
RC4	B-Algorithm
keystream	O
and	O
the	O
key	O
than	O
the	O
ones	O
found	O
by	O
Fluhrer	O
,	O
Mantin	O
,	O
and	O
Shamir	O
,	O
which	O
can	O
additionally	O
be	O
used	O
to	O
break	O
WEP	O
in	O
WEP-like	O
usage	O
modes	O
.	O
</s>
<s>
The	O
eavesdropped	O
packet	O
can	O
then	O
be	O
decrypted	O
one	O
byte	O
at	O
a	O
time	O
(	O
by	O
transmitting	O
about	O
128	O
packets	O
per	O
byte	O
to	O
decrypt	O
)	O
to	O
discover	O
the	O
local	B-General_Concept
network	I-General_Concept
IP	O
addresses	O
.	O
</s>
<s>
Finally	O
,	O
if	O
the	O
802.11	O
network	B-Architecture
is	O
connected	O
to	O
the	O
Internet	O
,	O
the	O
attacker	O
can	O
use	O
802.11	O
fragmentation	O
to	O
replay	O
eavesdropped	O
packets	O
while	O
crafting	O
a	O
new	O
IP	O
header	O
onto	O
them	O
.	O
</s>
<s>
The	O
access	B-Device
point	I-Device
can	O
then	O
be	O
used	O
to	O
decrypt	O
these	O
packets	O
and	O
relay	O
them	O
on	O
to	O
a	O
buddy	O
on	O
the	O
Internet	O
,	O
allowing	O
real-time	O
decryption	O
of	O
WEP	O
traffic	O
within	O
a	O
minute	O
of	O
eavesdropping	O
the	O
first	O
packet	O
.	O
</s>
<s>
With	O
the	O
new	O
attack	O
it	O
is	O
possible	O
to	O
recover	O
a	O
104-bit	O
WEP	B-Protocol
key	I-Protocol
with	O
a	O
probability	O
of	O
50%	O
using	O
only	O
40,000	O
captured	O
packets	O
.	O
</s>
<s>
The	O
actual	O
computation	O
takes	O
about	O
3	O
seconds	O
and	O
3MB	O
of	O
main	O
memory	O
on	O
a	O
Pentium-M	B-Architecture
1.7GHz	O
and	O
can	O
additionally	O
be	O
optimized	O
for	O
devices	O
with	O
slower	O
CPUs	O
.	O
</s>
<s>
In	O
2008	O
the	O
Payment	O
Card	O
Industry	O
Security	B-Application
Standards	O
Council	O
(	O
PCI	O
SSC	O
)	O
updated	O
the	O
Data	O
Security	B-Application
Standard	O
(	O
DSS	O
)	O
to	O
prohibit	O
use	O
of	O
WEP	O
as	O
part	O
of	O
any	O
credit-card	O
processing	O
after	O
30	O
June	O
2010	O
,	O
and	O
prohibit	O
any	O
new	O
system	O
from	O
being	O
installed	O
that	O
uses	O
WEP	O
after	O
31	O
March	O
2009	O
.	O
</s>
<s>
The	O
use	O
of	O
WEP	O
contributed	O
to	O
the	O
TJ	O
Maxx	O
parent	O
company	O
network	B-Architecture
invasion	O
.	O
</s>
<s>
It	O
is	O
not	O
necessary	O
for	O
the	O
attacker	O
to	O
be	O
in	O
the	O
area	O
of	O
the	O
network	B-Architecture
using	O
this	O
exploit	O
.	O
</s>
<s>
By	O
using	O
a	O
process	O
that	O
targets	O
the	O
Windows	B-Application
wireless	O
stack	O
,	O
it	O
is	O
possible	O
to	O
obtain	O
the	O
WEP	B-Protocol
key	I-Protocol
from	O
a	O
remote	O
client	O
.	O
</s>
<s>
By	O
sending	O
a	O
flood	O
of	O
encrypted	O
ARP	O
requests	O
,	O
the	O
assailant	O
takes	O
advantage	O
of	O
the	O
shared	B-Algorithm
key	I-Algorithm
authentication	O
and	O
the	O
message	O
modification	O
flaws	O
in	O
802.11	O
WEP	O
.	O
</s>
<s>
The	O
attacker	O
uses	O
the	O
ARP	O
responses	O
to	O
obtain	O
the	O
WEP	B-Protocol
key	I-Protocol
in	O
less	O
than	O
6	O
minutes	O
.	O
</s>
<s>
Use	O
of	O
encrypted	O
tunneling	B-Protocol
protocols	I-Protocol
(	O
e.g.	O
,	O
IPsec	B-Protocol
,	O
Secure	B-Protocol
Shell	I-Protocol
)	O
can	O
provide	O
secure	O
data	O
transmission	O
over	O
an	O
insecure	O
network	B-Architecture
.	O
</s>
<s>
However	O
,	O
replacements	O
for	O
WEP	O
have	O
been	O
developed	O
with	O
the	O
goal	O
of	O
restoring	O
security	B-Application
to	O
the	O
wireless	O
network	B-Architecture
itself	O
.	O
</s>
<s>
The	O
recommended	O
solution	O
to	O
WEP	O
security	B-Application
problems	O
is	O
to	O
switch	O
to	O
WPA2	O
.	O
</s>
<s>
To	O
add	O
support	O
for	O
WPA	O
or	O
WPA2	O
,	O
some	O
old	O
Wi-Fi	B-Device
access	I-Device
points	I-Device
might	O
need	O
to	O
be	O
replaced	O
or	O
have	O
their	O
firmware	B-Application
upgraded	O
.	O
</s>
<s>
However	O
,	O
TKIP	B-Protocol
(	O
the	O
basis	O
of	O
WPA	O
)	O
has	O
reached	O
the	O
end	O
of	O
its	O
designed	O
lifetime	O
,	O
has	O
been	O
partially	O
broken	O
,	O
and	O
has	O
been	O
officially	O
deprecated	O
with	O
the	O
release	O
of	O
the	O
802.11-2012	O
standard	O
.	O
</s>
<s>
After	O
it	O
became	O
clear	O
that	O
the	O
overall	O
WEP	O
algorithm	O
was	O
deficient	O
(	O
and	O
not	O
just	O
the	O
IV	O
and	O
key	O
sizes	O
)	O
and	O
would	O
require	O
even	O
more	O
fixes	O
,	O
both	O
the	O
WEP2	B-Protocol
name	O
and	O
original	O
algorithm	O
were	O
dropped	O
.	O
</s>
<s>
The	O
two	O
extended	O
key	O
lengths	O
remained	O
in	O
what	O
eventually	O
became	O
WPA	O
's	O
TKIP	B-Protocol
.	O
</s>
<s>
WEPplus	B-Protocol
,	O
also	O
known	O
as	O
WEP+	B-Protocol
,	O
is	O
a	O
proprietary	O
enhancement	O
to	O
WEP	O
by	O
Agere	O
Systems	O
(	O
formerly	O
a	O
subsidiary	O
of	O
Lucent	O
Technologies	O
)	O
that	O
enhances	O
WEP	O
security	B-Application
by	O
avoiding	O
"	O
weak	O
IVs	O
"	O
.	O
</s>
<s>
It	O
is	O
only	O
completely	O
effective	O
when	O
WEPplus	B-Protocol
is	O
used	O
at	O
both	O
ends	O
of	O
the	O
wireless	O
connection	O
.	O
</s>
<s>
Dynamic	O
WEP	O
refers	O
to	O
the	O
combination	O
of	O
802.1x	O
technology	O
and	O
the	O
Extensible	B-Protocol
Authentication	I-Protocol
Protocol	I-Protocol
.	O
</s>
<s>
Dynamic	O
WEP	O
changes	O
WEP	B-Protocol
keys	I-Protocol
dynamically	O
.	O
</s>
<s>
The	O
dynamic	O
change	O
idea	O
made	O
it	O
into	O
802.11i	O
as	O
part	O
of	O
TKIP	B-Protocol
,	O
but	O
not	O
for	O
the	O
WEP	O
protocol	O
itself	O
.	O
</s>
