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DCS 835 – Computer Networking and the Internet
IEEE 802.11 Wired Equivalent Privacy
(WEP)
Problems and Solutions
(rev. 6-19-05)
Team 4
Donald Little (project leader)
Jim Kile
Samir Shah
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Weaknesses & Solutions of WEP in IEEE 802.11 Networks, Study Guides, Projects, Research of Data Communication Systems and Computer Networks
An in-depth analysis of wired equivalent privacy (wep) in ieee 802.11 networks, discussing its background, technical description, and evaluating its weaknesses and solutions. Wep is a security protocol intended to provide the same level of security as ethernet at layer 2, but it has several vulnerabilities. Topics such as the importance of wep, its technical description, and the weaknesses and solutions to these issues.
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Pre 2010
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DCS 835 –
Computer Networking and the Internet
IEEE 802.11 Wired Equivalent Privacy
(WEP)
Problems and Solutions
(rev. 6-19-05)
Team 4
Donald Little (project leader)
Jim Kile Samir Shah
Topics
Background^ o
What is WEP? o
Why do we need WEP?
¾
Technical DescriptionHow does WEP work? ¾
EvaluationWhat are WEP’s weaknesses?What are the solutions to WEP’s weaknesses?
Why do we need WEP?
- Hackers can capture company’s digital assets• Hackers can use company’s wireless for attacks• Wireless signals can be picked up a mile or
more away with directional antenna
- Hackers sit in company parking lot (war
driving) and capture data
- Hackers have maps of known wireless site
s
Technical Description of WEP
• Optional security protocol for 802.11• Based on stream cipher algorithm RC4• Uses 64 or 128 bit encryption
24 bit Initialization Vector40 or 104 bit unique key
• Encryption relies on shared secret key, K
AB
Checksumming
- CRC-32 Integrity Checksum
c(M)
on message
M
- Concatenate the two to obtain plaintext
P=(M, c(M))
- c(M)
does not depend on
K
AB
P
does not depend on
K
AB
Initialization Vector, IV
- IV is 24 bit random number used to generate
the beginning of keystream
- “the IV may be changed as frequently as every
MPDU”
- Incremented with every new message
Encryption
- Exclusive-or (XOR) the plaintext with the
keystream to obtain the ciphertext
C = P
RC4 (IV, K
AB
XOR Encrypt
- PlainText
- Key
- Ciphertext
Encryption
Fig. 2 Encryption [10]
Symbolically
A
Æ
B: IV, ((M, c(M)
RC4(IV, K
AB
XOR Decrypt
- Ciphertext
- Key
- Plaintext
Decryption
Fig. 3 Decryption [10]
Brute Force Attack
- 40 bit possible for most hackers• 104 bit probably not possible with current
technology
Replay Attack
- Access Point and stations do not keep past
state
- Attackers can resend packets that they had
previously captured