Does 128bit WEP slow your machine down?

Since my previous post, I have managed to get 128bit WEP enabled on my
network. I do, however notice a slowing down of the system and wondered if
this was down to the higher 128bit encryption. Is it common for a fast
machine (2 GHz laptop) to notice a drop in performance when handling WEP.
Before setting up 128bit, I used 64bit WEP, which didn't appear to be
slowing things down at all...

I am now thinking of going back to 64bit WEP, instead of 128bit... Is
128bit double the security.. Or is 64bit sufficient for a home network?
There is no-one close enough to me to work about hacking in, and the
encryption is just a precaution.

I would value any comments and views on this
Thanks

Tony

"Tony" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> Since my previous post, I have managed to get 128bit WEP enabled on my
> network. I do, however notice a slowing down of the system and wondered
if
> this was down to the higher 128bit encryption. Is it common for a fast
> machine (2 GHz laptop) to notice a drop in performance when handling WEP.
> Before setting up 128bit, I used 64bit WEP, which didn't appear to be
> slowing things down at all...
>
> I am now thinking of going back to 64bit WEP, instead of 128bit... Is
> 128bit double the security.. Or is 64bit sufficient for a home network?
> There is no-one close enough to me to work about hacking in, and the
> encryption is just a precaution.

I haven't noticed it slowing down our machines themselves, but I did notice
it considerably seemed to slow the internet access (and therefore I guess
the networking) on the machine which connects wirelessly to our router (the
other goes in by cable) when I turned 128-bit WEP on - but its still about 4
times faster than dial-up, so its a reasonable trade off.

As for cracking the the WEP security, I guess it depends where you live. If
you're in a town/city then I guess you are more likely to have a 'neighbour'
in range wanting to crack it, whereas in the country the risk is probably
less likely.

"Tony" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> I am now thinking of going back to 64bit WEP, instead of 128bit... Is
> 128bit double the security.. Or is 64bit sufficient for a home network?

AFAIK, 128 bit WEP is theoretically 2^64 (18 * 10^18) times more secure than
64 bit .

Alex

"Alex Fraser" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> "Tony" <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed)...
> > I am now thinking of going back to 64bit WEP, instead of 128bit... Is
> > 128bit double the security.. Or is 64bit sufficient for a home network?
>
> AFAIK, 128 bit WEP is theoretically 2^64 (18 * 10^18) times more secure
than
> 64 bit .
>
> Alex
>

Alex... I don't understand your reply... Is 128bbit Wep twice as secure as
64 bit?

In article <(E-Mail Removed)>, "Tony" (E-Mail Removed)
says...
>
> "Alex Fraser" <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed)...
> > "Tony" <(E-Mail Removed)> wrote in message
> > news:(E-Mail Removed)...
> > > I am now thinking of going back to 64bit WEP, instead of 128bit... Is
> > > 128bit double the security.. Or is 64bit sufficient for a home network?
> >
> > AFAIK, 128 bit WEP is theoretically 2^64 (18 * 10^18) times more secure
> than
> > 64 bit .
> >
> > Alex
> >
>
> Alex... I don't understand your reply... Is 128bbit Wep twice as secure as
> 64 bit?
>
>
>
He's saying it's
2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x
2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x
2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x
2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x
2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x
2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x
2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x
2 x 2 x 2 x 2 x 2 x 2 x 2 x 2
times more secure, on the basis that it will take on average that much
longer to crack using brute-force methods and assuming that there isn't
a flaw in the encryption.

"Rob Morley" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) t...
> In article <(E-Mail Removed)>, "Tony" (E-Mail Removed)
> says...
> > "Alex Fraser" <(E-Mail Removed)> wrote in message
> > news:(E-Mail Removed)...
> > > "Tony" <(E-Mail Removed)> wrote in message
> > > news:(E-Mail Removed)...
> > > > I am now thinking of going back to 64bit WEP, instead of 128bit...
> > > > Is 128bit double the security.. Or is 64bit sufficient for a home
> > > > network?
> > >
> > > AFAIK, 128 bit WEP is theoretically 2^64 (18 * 10^18) times more
> > > secure than 64 bit .
> >
> > Alex... I don't understand your reply... Is 128bbit Wep twice as
> > secure as 64 bit?
>
> He's saying it's
> 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x
> 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x
> 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x
> 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x
> 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x
> 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x
> 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x
> 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2

= ~18,000,000,000,000,000,000

> times more secure, on the basis that it will take on average that much
> longer to crack using brute-force methods

As there are 2^64 128-bit WEP keys for each 64-bit WEP key.

> and assuming that there isn't a flaw in the encryption.

The point being that in the absence of a flaw, the only option is brute
force.

(To look at it another way, if you pick a key at random, you are 2^64 times
more likely to pick the correct key for 64-bit WEP as for 128-bit WEP.)

Alex

Every extra bit doubles the number of possible key values.
So for an 8 bit key there are 256 possible key values..
For 9 bits there are 512
So going from 64 to 128 bits means you need to try 2 to the power 64...

"Alex Fraser" <(E-Mail Removed)> wrote in message news:(E-Mail Removed)...
> "Tony" <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed)...
> > I am now thinking of going back to 64bit WEP, instead of 128bit...
> > Is 128bit double the security.. Or is 64bit sufficient for a home
> > network?
>
> AFAIK, 128 bit WEP is theoretically 2^64 (18 * 10^18) times more
> secure
than
> 64 bit .
>
> Alex
>

Alex... I don't understand your reply... Is 128bbit Wep twice as secure
as 64 bit?

Soni tempori elseu romani yeof helsforo nisson ol sefini ill des 15 Jul 2004
23:30:23 +0100, sefini jorgo geanyet des mani yeof do uk.comp.home-networking,
yawatina tan reek esk David Wade <(E-Mail Removed)> fornis do marikano es bono
tan el:

>> AFAIK, 128 bit WEP is theoretically 2^64 (18 * 10^18) times more
>> secure
>than
>> 64 bit .
>
>Alex... I don't understand your reply... Is 128bbit Wep twice as secure
>as 64 bit?

No, it's 18000000000000000000 times more secure

deKay
--
+ Lofi Gaming - www.lofi-gaming.org.uk AC: deKay in Sponge
|- ugvm Magazine - www.ugvm.org.uk Gamertag: deKay 01
|- My computer runs at 3.5MHz and I'm proud of that
|- Currently buying games at a rate of one every 14.33 hours

In message <(E-Mail Removed)>, deKay
<(E-Mail Removed)> writes
>Soni tempori elseu romani yeof helsforo nisson ol sefini ill des 15 Jul 2004
>23:30:23 +0100, sefini jorgo geanyet des mani yeof do uk.comp.home-networking,
>yawatina tan reek esk David Wade <(E-Mail Removed)> fornis do marikano es bono
>tan el:
>
>>> AFAIK, 128 bit WEP is theoretically 2^64 (18 * 10^18) times more
>>> secure
>>than
>>> 64 bit .
>>
>>Alex... I don't understand your reply... Is 128bbit Wep twice as secure
>>as 64 bit?
>
>No, it's 18000000000000000000 times more secure
>
Unfortunately, its not 18000000000000000000 times as secure because of
weaknesses in the way that the encryption is used rather than the
encryption scheme itself. These weakness leave WEP open to certain kinds
of attack that can reveal the 128 bit key much sooner. I don't know the
details but I believe that a 128 bit key can be discovered in about 3
times the time required to discover a 64 bit key *if* you attack it in
the right way.

This is similar to the techniques that allowed the team at Bletchly Park
to crack Enigma during the war. In the Enigma case, the code breakers
used their knowledge of the way the code was being used to guess the
content of the message and thus help them to obtain the keys. These were
termed 'cribs' and included such bits of knowledge as 'the first six
characters represented two copies of the session key - therefore the key
must produce the same results when decoding characters 4 to 6 as it did
when decoding characters 1 to 3'. Other cribs including the use of
standard broadcasts such as Weather Reports which were always sent at
the same time of day. If the Bletchly Park team got really desperate,
they would organise an air raid and listen for the reports.

Knowledge of the content of messages - so called cribs - allows the code
breaker to take shortcuts when trying to obtain keys. It is in this
area, rather than the absolute strength of the encryption used, that I
believe that WEP is weak.

Having said this, I believe it still takes a number of hours using a
large number of captured packets before the key discovery becomes likely
and so WEP encryption is better than nothing and 128 bit encryption is
better than 64 bit - just not 2**64 times better.

A new wireless encryption scheme called WPA is being introduces to
replace WEP which does not suffer from these weaknesses. Unfortunately,
a lot of devices out in the open can not be upgraded to use it.

--
Wade Oram
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