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Wireless Security. Presented by: Amit Kumar Singh Instructor : Dr. T. Andrew Yang. Going Wireless. Recent technologies include 802.11b,802.11g etc. Most commonly and widely present are 802.11b (11 mbps) 802.11b uses security techniques like WEP to make the network secure.

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Wireless security

Wireless Security

Presented by: Amit Kumar Singh

Instructor : Dr. T. Andrew Yang


Going wireless
Going Wireless

  • Recent technologies include 802.11b,802.11g etc.

  • Most commonly and widely present are 802.11b (11 mbps)

  • 802.11b uses security techniques like WEP to make the network secure.

  • IEEE came up with 802.11x standards for wireless ethernet.


What is wep
What is WEP ?

  • Wireless connections need to be secured since the intruders should not be allowed to access, read and modify the network traffic.

  • Mobile systems should be connected at the same time.

  • Algorithm is required which provides a high level of security as provided by the physical wired networks.

  • Protect wireless communication from eavesdropping, prevent unauthorized access.


Security goals of wep
Security Goals of WEP:

  • Access Control

    • Ensure that your wireless infrastructure is not used.

  • Data Integrity

    • Ensure that your data packets are not modified in transit.

  • Confidentiality

    • Ensure that contents of your wireless traffic is not leaked.


Understanding wep
Understanding WEP

  • WEP relies on a secret key which is shared between the sender (mobile station) and the receiver (access point).

  • Secret Key : packets are encrypted using the secret key before they are transmitted.

  • Integrity Check : it is used to ensure that packets are not modified in transit


Understanding wep contd
Understanding WEP contd…

  • To send a message to M:

    • Compute the checksum c(M). Checksum does not depend on the secret key ‘k’.

    • Pick a IV ‘v’ and generate a key stream RC4(v,k).

    • XOR <M,c(M)> with the key stream to get the cipher text.

    • Transmit ‘v’ and the cipher text over a radio link.


How wep works

Message

CRC

V

Cipher Text

How WEP Works

Plain Text

XOR

Key Stream = RC4(v,k)

Transmitted Data


How wep works1
How WEP works ?

  • WEP uses RC4 encryption algorithm known as “stream cipher” to protect the confidentiality of its data.

  • Stream cipher operates by expanding a short key into an infinite pseudo-random key stream.

  • Sender XOR’s the key stream with plaintext to produce cipher text.

  • Receiver has the copy of the same key, and uses it to generate an identical key stream.

  • XORing the key stream with the cipher text yields the original message.


Attack types
Attack types

  • Passive Attacks

    • To decrypt the traffic based on statistical analysis (Statistical Attack)

  • Active Attacks

    • To inject new traffic from authorized mobile stations, based on known plaintext.

  • Active Attacks

    • To decrypt the traffic based on tricking the access point

  • Dictionary Attacks

    • Allow real time automated decryption of all traffic.


Defenses of wep
Defenses of WEP

  • Integrity Check (IC) field

    • Used to ensure that packet has not been modified in transit

  • Initialization Vector (IV)

    • Used to avoid encrypting two cipher texts with the same key stream

    • Used to argument the shared key and produce a different RC4 key for each packet


References
References

  • http://www.cs.fsu.edu/~yasinsac/group/slides/cubukcu.pdf

  • http://www.isaac.cs.berkeley.edu/isaac/wep-faq.html

  • www.itserv.com/wireless

  • http://www.bluefiresecurity.com/bluefire_downloads.php?download=main

  • http://www.isaac.cs.berkeley.edu/isaac/mobicom.pdf


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