Wired Equivalent Privacy - WEP

Der Vortrag beschreibt das WEP-Verfahren und geht auf wesentliche Design- und Implementationsschwächen des Protokolls ein. Im Ausblick werden die Alternativen WPA und WPA2 (IEEE 802.11i) kurz vorgestellt.

Veranstaltung: C3D2-Themenabend "WLAN - Was nicht auf der Verpackung steht" (12.3.2004)

Download

• Folien: vortrag-wep-grundlagen.pdf (105k)
• Fragen und Antworten: nachtrag-wep-grundlagen.txt
• Literatur: hier
• Das Script checkkeygen.py demonstriert die Reduzierung der Key-Entropie nach [Newsham].

Ein schlechter WEP-Key Generator

$ python checkkeygen.py -h 

The script is intended to demonstrate the flaw of some 
40-Bit-Wep-Key generators, which is described in Tim 
Newsham's paper "Applying known techniques to WEP Keys".

=====================================================
=  Under no circumstances, DON'T EVEN THINK ABOUT,  =
=   to use this script to generate WEP-Keys !!!!    =
=====================================================   

Usage:
checkkeygen.py [options] [passphrase]

options:
    -h  this help
    -v  set verbosity (0,1,2,3)
    -m  modulo value of the LCPRNG (*)
    -a  multiplier value (*) 
    -c  offset constant (*)
    -t  number of values to put in trash, before key 
        generation (*)

passphrase:
    string, set in parantheses, if it contains spaces, e.g.
    "this is a string which contains spaces"

(*) The values can be expressions, because they are expanded
    with eval(), e.g. "2L**32" or "2L**32-1" or "0x123435" 
        

Literatur

WEP

[Interop] InteropNetLabs: What's Wrong With WEP?
(siehe auch hier)

[Whalen] Sean Whalen: Analysis of WEP and RC4 Algorithms

[BoGoWa] Borisov, Goldberg, Wagner: Security of the WEP algorithm

[StIoRu] Stubblefield, Ioannidis, Rubin: Using the Fluhrer, Mantin, and Shamir Attack to Break WEP

[RWeiss] Rüdiger Weiss: Wave-LAN: Wireless Encryption Placebo

[Newsham] Tim Newsham: Cracking WEP Keys - Applying known techniques to WEP Keys

WPA, 802.11i, 802.1X

[Eaton] (broken) Dennis Eaton: WLAN Security

[Eaton1] Dennis Eaton: 80211 Security

[ChrLink] Christian Link: 802. 11 (In) Security Overview