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WEP 128 versus 64

Author
3 Mar 2005 9:09 PM
paulh
Just wondered how much gain in throughput I'd get by dropping to WEP64
from 128.

Just out of interest, what is the process overhead of having WEP
enabled i.e in simple terms, how are the packets of data encrypted with
WEP key. Is it a big overhead.

Paul

Author
3 Mar 2005 9:55 PM
Steffo
Go with 128, some cards and routers don't even have 64 anymore: that means
something, innit?

pa***@fsmail.net wrote:
Show quoteHide quote
> Just wondered how much gain in throughput I'd get by dropping to WEP64
> from 128.
>
> Just out of interest, what is the process overhead of having WEP
> enabled i.e in simple terms, how are the packets of data encrypted
> with WEP key. Is it a big overhead.
>
> Paul
Author
4 Mar 2005 5:03 AM
Richard Perkin
"Steffo" <steffo@nospam.com> wrote in
news:422787c6$1_3@news.bluewin.ch:

> Go with 128, some cards and routers don't even have 64 anymore:
> that means something, innit?
>
> pa***@fsmail.net wrote:
>> Just wondered how much gain in throughput I'd get by dropping to
>> WEP64 from 128.
>>
>> Just out of interest, what is the process overhead of having WEP
>> enabled i.e in simple terms, how are the packets of data
>> encrypted with WEP key. Is it a big overhead.

There should be no (or minimal) processing overhead in using WEP
encryption with a 64 or 128 bit key. The encryption is done at
hardware level in the wireless chipset. There is an overhead of 4
bytes per packet for ciphertext (encrypted) data over plaintext (non-
encrypted) data.

If you want a reasonable overview of WEP encryption have a look here:
<http://developer.intel.com/technology/itj/q22000/articles/art_5.htm>

[Aside: This article has some confused language about authentication,
although the message is there if you read carefully: WEP with Open
System authentication is more secure than Shared Key]

Note that WPA uses the same RC4 encryption algorithm as WEP, but the
way the key and message integrity are handled is different. The use
of the same encryption is because it is done at the hardware level,
and otherwise would involve a hardware change.

This hardware change will be necessary for WPA2 encryption using AES
- again, the computationally intensive encryption is done at hardware
level, and only recent wireless chipsets include the necessary
algorithms.

Hope this helps

--

Richard Perkin
To email me, change the AT in the address below
richard.perkinATmyrealbox.com

It's is not, it isn't ain't, and it's it's, not its, if you mean it
is.  If you don't, it's its.  Then too, it's hers.  It isn't her's.
It isn't our's either.  It's ours, and likewise yours and theirs.
-- Oxford University Press, Edpress News
Author
3 Mar 2005 10:43 PM
Airhead
<pa***@fsmail.net> wrote in message
news:1109884147.130074.32190@o13g2000cwo.googlegroups.com...
> Just wondered how much gain in throughput I'd get by dropping to
WEP64
> from 128.
>
> Just out of interest, what is the process overhead of having WEP
> enabled i.e in simple terms, how are the packets of data encrypted
with
> WEP key. Is it a big overhead.

Any encryption takes time and processing power and 128 takes more than
64.
If someone really wants to crack you it makes no difference which one
you use.
Author
3 Mar 2005 10:48 PM
Thomas Krüger
pa***@fsmail.net wrote:

> Just wondered how much gain in throughput I'd get by dropping to WEP64
> from 128.

Nothing, the encrytiong work the same way only the keystrem is generated
from a short initial value. And the keystrem is always as long as the data
you send.

Thomas
Author
4 Mar 2005 1:20 PM
Airhead
<pa***@fsmail.net> wrote in message
news:1109884147.130074.32190@o13g2000cwo.googlegroups.com...
> Just wondered how much gain in throughput I'd get by dropping to
WEP64
> from 128.
>
> Just out of interest, what is the process overhead of having WEP
> enabled i.e in simple terms, how are the packets of data encrypted
with
> WEP key. Is it a big overhead.

For grins I ran a throughput test with both.

64 wep decreased throughput by an average of 7.9%
128 wep decreased throughput by an average of 9.7%

Just a 1.8% difference.. Not enough to worry about.