WEP cracked even worse

[Ralf-Philipp Weinmann]

On Apr 4, 2007, at 03:38 , Dave Korn wrote:

> On 04 April 2007 00:44, Perry E. Metzger wrote:
>
>> Not that WEP has been considered remotely secure for some time, but
>> the best crack is now down to 40,000 packets for a 50% chance of
>> cracking the key.
>>
>> http://www.cdc.informatik.tu-darmstadt.de/aircrack-ptw/
>
>
>   Sorry, is that actually better than "The final nail in WEP's  
> coffin", which
> IIUIC can get the entire keystream (who needs the key?) in log2 
> (nbytes) packet
> exchanges (to oversimplify a bit, but about right order-of-magnitude)?


Hi Dave,

this of course is a question of how you value an attack: a key  
recovery usually is worth more than a decryption oracle.

To send arbitrary packets with the fragmentation attacks described in  
[1, Section 2.6], you need just a single (suitable) data packet.  
However, in order to decrypt packets, you need either 2 (connectivity  
to other networks that you have a host on that you can control, e.g  
the internet) or approx. 2^7 packets (no access to outside hosts)  
_per byte_ that you want to decrypt. Our method surely pays of if you  
want to decrypt more than a handful of packets.

Cheers,
Ralf

[1] Andrea Bittau, Mark Handley, Joshua Lackey
     The Final Nail in WEP’s Coffin
     IEEE Symposium on Security and Privacy 2006,
     http://doi.ieeecomputersociety.org/10.1109/SP.2006.40
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