IP: New results on WEP (fwd)

[David Farber <dave () farber net>]

> To: cryptography () wasabisystems com
> Subject: New results on WEP (fwd)
> Date: Wed, 25 Jul 2001 19:13:29 -0400
> From: Matt Blaze <mab () research att com>
> Sender: owner-cryptography () wasabisystems com
>
>
> Adi Shamir and his colleagues have some interesting
> new results on RC4 with a practical attack against WEP.
> With Adi's permission, I've made available a (PostScript)
> copy of a draft of his paper at:
>   http://www.crypto.com/papers/others/rc4_ksaproc.ps
>
> (Fortunately, as far as I know WEP isn't used for copy protection,
> so it's still legal to disseminate and traffic in this kind
> of information...)
>
> - -matt
>
> - ------ Forwarded Message
>
> Date: Thu, 26 Jul 2001 00:50:03 +0300
> From: Shamir Adi <shamir () wisdom weizmann ac il>
> Organization: Weizmann Institute of Sciense, Faculty of Mathematics
> To: mab () research att com
> Subject: New results on WEP
>
> Dear Matt,
>
> WEP is the security protocol used in the widely deployed
> IEEE 802.11 wireless LAN's. This protocol received a lot
> of attention this year, and several groups of researchers
> have described a number of ways to bypass its security.
>
> Attached you will find a new paper which describes a truly
> practical direct attack on WEP's cryptography. It is an
> extremely powerful attack which can be applied even when
> WEP's RC4 stream cipher uses a 2048 bit secret key (its
> maximal size) and 128 bit IV modifiers (as proposed in WEP2).
> The attacker can be a completely passive eavesdropper (i.e.,
> he does not have to inject packets, monitor responses, or
> use accomplices) and thus his existence is essentially
> undetectable. It is a pure known-ciphertext attack
> (i.e., the attacker need not know or choose their
> corresponding plaintexts). After scanning several hundred
> thousand packets, the attacker can completely recover the
> secret key and thus decrypt all the ciphertexts. The running
> time of the attack grows linearly instead of exponentially
> with the key size, and thus it is negligible even for 2048
> bit keys.
>
> I'll appreciate your comments and suggestions. Please feel
> free to forward this email to your colleagues.
>
>
> Sincerely yours,
>
> Adi Shamir



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